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“Schwingshackl, L., et al. (2017): Food groups and risk of all-cause mortality: a systematic review and meta-analysis of prospective studies. In: Am J Clin Nutr. URL: https://academic.oup.com/ajcn/article/105/6/1462/4569801.) heart disease,”
By Vincent Sparanga | Reading Time: 27 minutes |
Most basically, the carnivore diet only includes animal meat, but some people incorporate eggs and dairy too.[1]Meat Health: The Carnivore Diet – What to Eat. URL: https://meat.health/knowledge-base/carnivore-diet-what-to-eat/. Recently, the carnivore diet has become popular,[2]Google Trends: Carnivore Diet. URL: https://trends.google.com/trends/explore?date=today%205-y&geo=US&q=carnivore%20diet. because it can spur fat loss, reduce bloating, and improve subjective well-being.[3]Hyson, S. (2019): The Carnivore Diet: Is Eating ONLY Meat Healthy, or Totally F@#$ing Crazy? In: Onnit.com. URL: https://www.onnit.com/academy/the-carnivore-diet/.
Indeed, many find that the diet works, despite the fact that carnivores eliminate most food groups. So, why does the carnivore diet help so many people?
Contents
The Carnivore Diet: Good or Bad?
The Benefits of a Carnivore Diet
Consistency & Simplicity
When you only eat meat, it’s easy to establish a daily routine, as hunger may become more predictable. This makes it easier to maintain consistent dietary patterns,[4]Feig, EH. / Lowe, MR. (2017): Variability in Weight Change Early in Behavioral Weight Loss Treatment: Theoretical and Clinical Implications. In: Obes. URL: https://www.ncbi.nlm.nih.gov/pubmed/28845608. which usually improves diet success.[5]Gorin, AA., et al. (2004): Promoting long-term weight control: does dieting consistency matter? In: Int J Obes Relat Metab Disord. URL: https://www.ncbi.nlm.nih.gov/pubmed/14647183.[6]Melby, CL., et al. (2017): Attenuating the Biologic Drive for Weight Regain Following Weight Loss: Must What Goes Down Always Go Back Up? In: Nutrients. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5452198/.[7]Thomas, JG., et al. (2014): Weight-loss maintenance for 10 years in the National Weight Control Registry. In: Am J Prev Med. URL: https://www.ncbi.nlm.nih.gov/pubmed/24355667.[8]Karfopoulou, E., et al. (2017): Dietary patterns in weight loss maintenance: results from the MedWeight study. In: Eur J Nutr. URL: https://www.ncbi.nlm.nih.gov/pubmed/26744302/.[9]Rosenbaum, DL., et al. (2016): Energy intake highs and lows: how much does consistency matter in weight control? In: Clin Obes. URL: https://www.ncbi.nlm.nih.gov/pubmed/27020845.
The diet has just one, basic rule: you only eat meat. This simplifies meal-planning, which may thereby improve adherence/weight loss,[10]Ducrot, P., et al. (2017): Meal planning is associated with food variety, diet quality and body weight status in a large sample of French adults. In: Int J Behav Nutr Phys Act. URL: https://ijbnpa.biomedcentral.com/articles/10.1186/s12966-017-0461-7. perhaps due to reduced stress.[11]Christensen, BJ., et al. (2017): Instrumentalization of Eating Improves Weight Loss Maintenance in Obesity. In: Obes Facts. URL: https://www.ncbi.nlm.nih.gov/pubmed/29207396.
What is the difference between people who successfully lose weight and maintain this weight over the long term (weight reducers) and those who gain weight again afterwards (weight regainers)? Christensen’s study provides us with an answer to this question: structured nutritional plans, no frustration and less psychosocial stress. (Graphic Source: Christensen et al., 2017)
Meat is pretty easy to buy and cook, so meal prep is usually a breeze for carnivores. Even at social events, you can usually find meat.
Mindfulness
The carnivore diet typically increases dietary awareness, as it coincides with deliberate changes in food selection and reduced appetite. Since carnivores have to alter their food choices, they necessarily engage self-monitoring.
This greater self-monitoring is often associated with greater weight loss (e.g. with food logging and daily weighing.[12]Olson, KL. / Emery, CF. (2015): Mindfulness and weight loss: a systematic review. In: Psychosom Med. URL: https://www.ncbi.nlm.nih.gov/pubmed/25490697.[13]Ruffault, A., et al. (2017): The effects of mindfulness training on weight-loss and health-related behaviours in adults with overweight and obesity: A systematic review and meta-analysis. In: Obes Res Clin Pract. URL: https://www.ncbi.nlm.nih.gov/pubmed/27658995.[14]Burke, LA / Wang, J. / Sevick, MA. (2011): Self-Monitoring in Weight Loss: A Systematic Review of the Literature. In: J Am Diet Assoc. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3268700/.[15]Steinberg, DM., et al. (2015): Weighing everyday matters: Daily weighing improves weight loss and adoption of weight control behaviors. In: J Acad Nutr Diet. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4380831/.[16]Kaviani, S. / van Dellen, M. / Cooper, JA. (2019): Daily Self-Weighing to Prevent Holiday-Associated Weight Gain in Adults. In: Obesity. URL: https://www.ncbi.nlm.nih.gov/pubmed/31119881.
Food Reward & Satisfaction
This diet modulates food reward well, which is important, as rewarding foods can override satiety. For most people, meat is tasty enough to eat, but not so delicious that they risk overeating.[17]Schulte, EM. / Avena, NM. / Gearhardt, AN. (2015): Which Foods May Be Addictive? The Roles of Processing, Fat Content, and Glycemic Load. In: PLoS One. URL: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0117959.
Adherence is an important key to weight loss success, and there are a number of strategies that can be used to improve adherence that are applicable in research or real-world settings. An increased drive to eat is a major contributor to unsuccessful weight loss attempts, and thus it is a key target in improving adherence. Diets which induce ketosis (such as VLEDs or KLCDs) may help to control the increased drive to eat associated with weight loss, but further research is needed on the level of carbohydrate restriction that is required to achieve this. Ensuring that a diet contains adequate protein may also help to prevent an increase in the drive to eat. In addition, a dietary intervention that is tailored to a person’s dietary preferences (whilst still aligning with nutritional recommendations), may also improve adherence.
Gibson & Sainsbury, 2017When you only eat meat, you also cut out the processed, less-satiating, addictive, calorie-dense, hyper-palatable foods (e.g. chocolate, ice cream, and french fries),[18]Schulte, EM. / Avena, NM. / Gearhardt, AN. (2015): Which Foods May Be Addictive? The Roles of Processing, Fat Content, and Glycemic Load. In: PLoS One. URL: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0117959. that promote fat gain.[19]Hall, KD., et al. (2019): Ultra-Processed Diets Cause Excess Calorie Intakeand Weight Gain: An Inpatient RandomizedControlled Trial ofAd LibitumFood Intake. In: Cell Metab. URL: https://www.cell.com/cell-metabolism/pdf/S1550-4131(19)30248-7.pdf. Therefore, carnivores have less incentive to over-indulge.
At least for meat-lovers, the carnivore diet is typically satisfying, as it probably mimics their baseline diet.[20]Gibson, AA. / Sainsbury, A. (2017): Strategies to Improve Adherence to Dietary Weight Loss Interventions in Research and Real-World Settings. In: Behav Sci. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5618052/. Dietary enjoyment can improve adherence,[21]Gibson, AA. / Sainsbury, A. (2017): Strategies to Improve Adherence to Dietary Weight Loss Interventions in Research and Real-World Settings. In: Behav Sci. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5618052/. which drives fat loss/muscle gain.[22]Aragon, AA., et al. (2017): International society of sports nutrition position stand: diets and body composition. In: J Int Soc Sports Nutr. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5470183/.[23]Alhassan, S., et al. (2008): Dietary adherence and weight loss success among overweight women: results from the A TO Z weight loss study. In: Int J Obes. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4005268/.[24]Thom, G. / Lean, M. (2017): Is There an Optimal Diet for Weight Management and Metabolic Health? In: Gastroenterol. URL: https://www.ncbi.nlm.nih.gov/pubmed/28214525.
Protein, Satiety & Calorie Control
The carnivore diet is high in protein, which helps preserve lean mass and energy expenditure.[25]Cava, E. / Yeat, NC. / Mittendorfer, B. (2017): Preserving Healthy Muscle during Weight Loss. In: Adv Nutr. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5421125/.[26]Whitehead, JM. / McNeill, G. / Smith, JS. (1996): The effect of protein intake on 24-h energy expenditure during energy restriction. In: Int J Obes Relat Metab Disord. URL: https://www.ncbi.nlm.nih.gov/pubmed/8856395.[27]Agus, MSD., et al. (2000): Dietary composition and physiologic adaptations to energy restriction. In: Am J Clin Nutr. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2905862/.[28]Teske, TA. / Billington, CJ. / Kotz, CM. (2008): Neuropeptidergic Mediators of Spontaneous Physical Activity and Non-Exercise Activity Thermogenesis. In: Neuroendocrinol. URL: https://www.ncbi.nlm.nih.gov/pubmed/17984627/. Both functions seem to augment better body composition.[29]Leaf, A. / Antonio, J. (2017): The Effects of Overfeeding on Body Composition: The Role of Macronutrient Composition – A Narrative Review. In: Int J Exerc Sci. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5786199/.[30]Morton, RW., et al. (2018): A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. In: Br J Sports Med. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5867436/.
Plus, protein has shown potential to reduce calorie intake,[31]Pesta, DH. / Samuel, VT. (2014): A high-protein diet for reducing body fat: mechanisms and possible caveats. In: Nutr Metab. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4258944/. while high protein intake correlates with better weight management.[32]Leidy, HJ., et al. (2015): The role of protein in weight loss and maintenance. In: Am J Clin Nutr. URL: https://www.ncbi.nlm.nih.gov/pubmed/25926512.
The carnivore diet often blunts hunger and appetite. This is partially due to carbohydrate or calorie restriction,[33]Gibson, AA., et al. (1995): Do ketogenic diets really suppress appetite? A systematic review and meta-analysis. In: Obes Rev. URL: https://www.ncbi.nlm.nih.gov/pubmed/25402637. but also given meat’s high satiety index score and protein content.[34]Holt, SHA., et al. (1995): A Satiety Index of common foods. In: Eur J Clin Nutr. URL: https://www.researchgate.net/publication/15701207_A_Satiety_Index_of_common_foods.[35]Phelan, S., et al. (2018): Randomized controlled clinical trial of behavioral lifestyle intervention with partial meal replacement to reduce excessive gestational weight gain. In: Am J Clin Nutr. URL: https://www.ncbi.nlm.nih.gov/pubmed/29529157. Since it reduces your desire to eat at any given time, the carnivore diet potentiates fat loss.
That makes sense, since decreased hunger strongly predicts weight loss,[36]Batra, P., et al. (2013): Eating behaviors as predictors of weight loss in a 6 month weight loss intervention. In: Obesity. URL: https://www.ncbi.nlm.nih.gov/pubmed/23512619. while higher protein diets correlate with reduced fat gain and increased weight loss.[37]Leaf, A. / Antonio, J. (2017): The Effects of Overfeeding on Body Composition: The Role of Macronutrient Composition – A Narrative Review. In: Int J Exerc Sci. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5786199/.[38]Pesta, DH. / Samuel, VT. (2014): A high-protein diet for reducing body fat: mechanisms and possible caveats. In: Nutr Metab. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4258944/.[39]Shin, SM. (2017): Association of Meat Intake with Overweight and Obesity among School-aged Children and Adolescents. In: J Obes Metab Syndr. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6484919/. Moreover, this seemingly matches the findings that low meat intake correlates with obesity.[40]Shin, SM. (2017): Association of Meat Intake with Overweight and Obesity among School-aged Children and Adolescents. In: J Obes Metab Syndr. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6484919/.
Given the above benefits, the carnivore diet often promotes lower energy intake. The diet makes it difficult to overeat, so fat loss may become easy for most carnivores.
FODMAPs
These are carbs (fermentable oligo-, di- and monosaccharides and polyols) that can cause gas, bloating, stomach pain, indigestion, constipation, and the like.[41]Gibson, PR. / Shepherd, SJ. (2010): Evidence‐based dietary management of functional gastrointestinal symptoms: The FODMAP approach. In: J Gastroenterol Hepatol. URL: https://onlinelibrary.wiley.com/doi/full/10.1111/j.1440-1746.2009.06149.x.[42]Barrett, JS. / Gibson, PR. (2012): Fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) and nonallergic food intolerance: FODMAPs or food chemicals? In: Therap Adv Gastroenterol. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3388522/.
Foods with high (black) and low (grey) oligosaccharide content (in grams/portion) – a meat-based diet can justifiably be understood as a low-FODMAP diet. (Graphic Source: Varney et al., 2016)
Those with FODMAP intolerances and gut issues often find relief when they cut out FODMAP-containing carbohydrates/plant foods.[43]Staudacher, HM., et al. (2011): Comparison of symptom response following advice for a diet low in fermentable carbohydrates (FODMAPs) versus standard dietary advice in patients with irritable bowel syndrome. In: J Hum Nutr Diet. URL: https://www.ncbi.nlm.nih.gov/pubmed/21615553.[44]Halmos, EP., et al. (2014): A diet low in FODMAPs reduces symptoms of irritable bowel syndrome. In: Gastroenterol. URL: https://www.ncbi.nlm.nih.gov/pubmed/24076059.
Individuals suffering from IBS benefit from a FODMAP-poor diet within a few days. A low FODMAP diet reduces bloating and abdominal pain, while promoting stool consistency. Those who experience gut issues from eating FODMAP-containing foods could benefit from such a diet, which might relieve symptoms associated with disturbed digestion. (Graphic Source: Halmos et al., 2014)
In essence, the carnivore diet removes all FODMAPs, which combats (otherwise frustrating) stomach issues.[45]Ostgaard, H., et al. (2012): Diet and effects of diet management on quality of life and symptoms in patients with irritable bowel syndrome. In: Mol Med Rep. URL: https://www.ncbi.nlm.nih.gov/pubmed/22446969.
Insulin Resistance
For the insulin-resistant, high carbohydrate intake may increase risk of weight gain, as compared to low carb intake.[46]Stanhope, KL., et al. (2018): Pathways and mechanisms linking dietary components to cardiometabolic disease: thinking beyond calories. In: Obes Rev. URL: https://drive.google.com/file/d/0B52J0hYW7iGYemVxN2VlUVVHemxjMUhTdXJwaXoxOFNRem5F/view?usp=sharing. Similarly, multiple studies report greater fat loss[47]Klemsdal, TO., et al. (2010): Effects of a low glycemic load diet versus a low-fat diet in subjects with and without the metabolic syndrome. In: Nutr Metab Cardiovasc. URL: https://www.sciencedirect.com/science/article/pii/S0939475309000702.[48]Gower, BA. / Goss, AM. (2015): A Lower-Carbohydrate, Higher-Fat Diet Reduces Abdominal and Intermuscular Fat and Increases Insulin Sensitivity in Adults at Risk of Type 2 Diabetes. In: J Nutr. URL: https://academic.oup.com/jn/article/145/1/177S/4585793.[49]Juanola-Falgarona, M., et al. (2014): Effect of the glycemic index of the diet on weight loss, modulation of satiety, inflammation, and other metabolic risk factors: a randomized controlled trial. In: Am J Clin Nutr. URL: https://academic.oup.com/ajcn/article/100/1/27/4576555.[50]Goss, AM., et al. (2014): Effects of a eucaloric reduced-carbohydrate diet on body composition and fat distribution in women with PCOS. In: Metab. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4191914/. and adherence,[51]McClain, AD., et al. (2012): Adherence to a low‐fat vs. low‐carbohydrate diet differs by insulin resistance status. In: Diab Obes Metab. URL: https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1463-1326.2012.01668.x?deniedAccessCustomisedMessage=&userIsAuthenticated=false. when less-insulin sensitive dieters eat a low-glycemic load diet (however, not always[52]Mediano, MFF. / Sichieri, R. (2012): Insulin Resistance Predicts the Effectiveness of Different Glycemic Index Diets on Weight Loss in Non-Obese Women. In: Karger. URL: https://www.karger.com/Article/Abstract/343507.[53]Hall, KD., et al. (2015): Calorie for Calorie, Dietary Fat Restriction Results in More Body Fat Loss than Carbohydrate Restriction in People with Obesity. In: Cell Metab. URL: https://www.sciencedirect.com/science/article/pii/S1550413115003502?via%3Dihub.[54]Gardner, CD., et al. (2018): Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion. The DIETFITS Randomized Clinical Trial. In: JAMA. URL: https://jamanetwork.com/journals/jama/fullarticle/2673150.[55]Hall, KD., et al. (2016): Energy expenditure and body composition changes after an isocaloric ketogenic diet in overweight and obese men. In: Am J Clin Nutr. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4962163/.[56]Gardner, CD., et al. (2016): Weight Loss on Low-Fat vs. Low-Carb Diets by Insulin Resistance Status Among Overweight Adults & Adults with Obesity: A Randomized Pilot Trial. In: Obes. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5898445/.).
Average weight change (from baseline) during a 6-month study in overweight subjects who followed a diet that had either a high (HG) or low (LG) glycemic load. The subjects were grouped into “Low INS-30” and “High INS-30” according to their insulin status (based on insulin secretion 30 minutes after an oral glucose tolerance test (75mg glucose)). (Graphic Source: Pittas et al., 2005)
Supporting these findings, some research suggests that insulin-sensitive individuals lose more fat on higher carbohydrate diets[57]Rock, CL, et al. (2016): Effects of diet composition on weight loss, metabolic factors and biomarkers in a 1-year weight loss intervention in obese women examined by baseline insulin resistance status. In: Metab Clin Exp. URL: https://www.metabolismjournal.com/article/S0026-0495(16)30072-5/abstract.[58]Cornier, MA., et al. (2012): Insulin Sensitivity Determines the Effectiveness of Dietary Macronutrient Composition on Weight Loss in Obese Women. In: Obes. URL: https://onlinelibrary.wiley.com/doi/full/10.1038/oby.2005.79. (but again, not always[59]Gardner, CD., et al. (2018): Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion. The DIETFITS Randomized Clinical Trial. In: JAMA. URL: https://jamanetwork.com/journals/jama/fullarticle/2673150.[60]Gardner, CD., et al. (2016): Weight Loss on Low-Fat vs. Low-Carb Diets by Insulin Resistance Status Among Overweight Adults & Adults with Obesity: A Randomized Pilot Trial. In: Obes. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5898445/.[61]Mediano, MFF. / Sichieri, R. (2012): Insulin Resistance Predicts the Effectiveness of Different Glycemic Index Diets on Weight Loss in Non-Obese Women. In: Karger. URL: https://www.karger.com/Article/Abstract/343507.).
Absolute (A) and percentage (B) changes in body weight (BW) in insulin-resistant (IS) and insulin-sensitive (IS) women who followed a hypocaloric HC/LF or LC/HF diet for a period of 16 weeks. (Graphic Source: Cornier et al., 2005)
So, while effects seem to be highly individual, insulin-resistant dieters often experience greater fat loss with lower carbohydrate intakes.[62]Stanhope, KL., et al. (2018): Pathways and mechanisms linking dietary components to cardiometabolic disease: thinking beyond calories. In: Obes Rev. URL: https://drive.google.com/file/d/0B52J0hYW7iGYemVxN2VlUVVHemxjMUhTdXJwaXoxOFNRem5F/view?usp=sharing. As such, the carnivore diet (no carbs) can improve weight loss among the insulin resistant.
Dental Health
The carnivore diet usually eliminates sugar intake. This can be great for dental health, as “free sugar” intake correlates closely with cavities.[63]Moynihan, P. (2016): Sugars and Dental Caries: Evidence for Setting a Recommended Threshold for Intake. In: Adv Nutr. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4717883/.[64]Sheiham, A. / James, WP. (2014): A new understanding of the relationship between sugars, dental caries and fluoride use: implications for limits on sugars consumption. In: Public Health Nutr. URL: https://www.ncbi.nlm.nih.gov/pubmed/24892213.[65]Sheiham, A. / James, WPT. (2014): A reappraisal of the quantitative relationship between sugar intake and dental caries: the need for new criteria for developing goals for sugar intake. In: BMC Public Health. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4168053/. Thus, removing sugar from your diet may preserve your teeth.
Relationship between annual sugar consumption and cumulative incidence of caries in the upper incisors with a tooth age of up to 8 years (3-D model) in Japan between 1935-1957. (Graphic Source: Sheiham & James, 2014, after Takeuchi et al., 1971)
The Downsides of a Carnivore Diet
While there are many benefits to carnivore, there are a few legitimate concerns about the diet.
Nutrient Deficiency
Unfortunately, even a nutrient-dense carnivore diet risks multiple nutrient deficiencies.[66]Engel, MG., et al. (2018): Micronutrient Gaps in Three Commercial Weight-Loss Diet Plans. In: Nutrients. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5793336/.[67]Calton, JB. (2010): Prevalence of Micronutrient Deficiency in Popular Diet Plans. In: J Int Soc Sports Nutr. URL: https://www.ncbi.nlm.nih.gov/pubmed/20537171. More specifically, carnivores risk vitamin K, vitamin C, potassium, and calcium deficiencies.
Sample nutritional weight loss plan on a nutrient-rich Carnivore Diet with the goal of weight loss (500 kcal deficit/day). (Graphic Source: Sparagna, 2019)
Associated nutritional profile, for example, nutritional plan on a Carnivore Diet. (Graphic Source: Sparagna, 2019)
Indeed, despite eating a variety of meats with differing nutrient profiles, carnivores still face some potential concerns.
Nutrients of some concern
Vitamin D and sodium are rare in meat, but you can avoid deficiency by simply getting sun exposure and salting your meat (see salt to sodium conversion).
Similarly, while most meats lack calcium, you can prevent deficiency by adding some dairy to your diet.[68]Adam, MP., et al. (2015): Ataxia with Vitamin E Deficiency. In: Gene Rev. URL: https://www.ncbi.nlm.nih.gov/books/NBK1241/. Lastly, while vitamin E is also rare in meat, vitamin E deficiency is extremely rare[69]Adam, MP., et al. (2015): Ataxia with Vitamin E Deficiency. In: Gene Rev. URL: https://www.ncbi.nlm.nih.gov/books/NBK1241/. (only seen with genetic abnormalities and fat malabsorption syndrome.[70]Ministry of Health: Vitamin E. URL: https://www.nrv.gov.au/nutrients/vitamin-e.
As such, vitamin E deficiency is of little concern, while sodium, calcium, and vitamin D deficiencies are all easily avoided.
Nutrients of more concern
Vitamin C, Vitamin K1, and potassium are very scarce on the carnivore diet. Carnivores should consider supplementing these nutrients.
Vitamin K
While meats are often high in the rare vitamin K2, they lack vitamin K1.[71]Masterjohn, C. (2016): The Ultimate Vitamin K2 Resource. In: Chrismasterjohnpd.com. URL: https://chrismasterjohnphd.com/blog/2016/12/09/the-ultimate-vitamin-k2-resource/. For reference, vitamin K deficiency has been observed in those eating less than 10 µg of vitamin K per day (i.e. <10% RDA).[72]Institute of Medicine: Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. URL: https://www.ncbi.nlm.nih.gov/books/NBK222299/.
On a nutrient-dense carnivore diet, we see just over 10% of the RDA for vitamin K, which suggests that carnivores can avoid short-term deficiency.
However, while carnivores can avoid short-term issues, it’s still not clear whether carnivores risk long-term vitamin K deficiency. The main problems seen with vitamin K deficiency are bleeding and fat malabsorption.[73]Ministry of Health: Vitamin K. URL: https://www.nrv.gov.au/nutrients/vitamin-k.
Vitamin C
Meats are very low in vitamin C. In the nutrient-dense carnivore diet nutrient profile, we see just 17.2 mg of vitamin C per day (19% DV).
Luckily, vitamin C deficiency seems to occur at intakes less than 7-8 mg/day of vitamin C, which is lower than this 17.2 mg figure. As such, while carnivores don’t necessarily risk vitamin C deficiency, they should take care to ensure adequate vitamin C intake.
The main con to vitamin C deficiency is scurvy, which entails skeletal and vascular lesions with gingival changes, pain in the extremities, haemorrhage, oedema, ulcerations, and death.[74]Ministry of Health: Vitamin C. URL: https://www.nrv.gov.au/nutrients/vitamin-c.
You can probably get enough vitamin C by eating specific meats (e.g. oysters, mussels, and raw fish eggs/caviar)[75]Fediuk, K., et al. (2002): Vitamin C in Inuit Traditional Food and Women’s Diets. In: J Food Comp Anal. URL: https://www.sciencedirect.com/science/article/pii/S0889157502910537. and certain dairy products.[76]Abjcn.nhri.org.tw: Vitamin C. URL: http://apjcn.nhri.org.tw/server/info/books-phds/books/foodfacts/html/data/data4i.html.
Potassium
It’s not clear whether or not carnivores get enough potassium. Unfortunately, even the recommended daily intake for potassium lacks a strong supporting rationale.[77]Ministry of Health: Potassium. URL: https://www.nrv.gov.au/nutrients/potassium.
Side effects to potassium deficiency include weakness and fatigue,[78]Meltem, AC., et al. (2009): A hypokalemic muscular weakness after licorice ingestion: a case report. In: Cases J. URL: https://www.ncbi.nlm.nih.gov/pubmed/20181204. muscle cramps,[79]McGee, SR. (1990): Muscle Cramps. In: JAMA. URL: https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/612935. muscle aches and stiffness,[80]Wen, Z., et al. (2013): Rhabdomyolysis presenting with severe hypokalemia in hypertensive patients: a case series. In: BMC Res Notes. URL: https://www.ncbi.nlm.nih.gov/pubmed/23594380. tingles and numbness,[81]Viera, AJ., et al. (2015): Potassium Disorders: Hypokalemia and Hyperkalemia. In: https://www.aafp.org/afp/2015/0915/p487.html. heart palpitations,[82]Olivero, JJ. (2016): Cardiac Consequences Of Electrolyte Imbalance. In: Methodist Debakey Cardiovasc J. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4969023/.[83]Osadchii, OE. (2010): Mechanisms of hypokalemia-induced ventricular arrhythmogenicity. In: Fundam Clin Pharmacol. URL: https://www.ncbi.nlm.nih.gov/pubmed/20584206. breathing difficulties,[84]Alvarez, J. / Low, RB. (1988): Acute respiratory arrest due to hypokalemia. In: Ann Emerg Med. URL: https://www.ncbi.nlm.nih.gov/pubmed/3345025.[85]Armstrong, ML. / Dua, AK. / Murrant, CL. (2007): Potassium initiates vasodilatation induced by a single skeletal muscle contraction in hamster cremaster muscle. In: J Physiol. URL: https://www.ncbi.nlm.nih.gov/pubmed/17363384. digestive symptoms[86]Vogalis, F. (2000): Potassium channels in gastrointestinal smooth muscle. In: J Auton Pharmacol. URL: https://www.ncbi.nlm.nih.gov/pubmed/11260359.[87]Verga, S., et al. (2017): The Importance of Serum Electrolytes: A Case of Hypokalemic Periodic Paralysis. In: ATS J. URL: https://www.atsjournals.org/doi/abs/10.1164/ajrccm-conference.2017.195.1_MeetingAbstracts.A3838. and mood changes.[88]Inshasi, JS., et al. (1999): Dysfunction of sensory nerves during attacks of hypokalemic periodic paralysis. In: Neuromuscul Disord. URL: https://www.ncbi.nlm.nih.gov/pubmed/10399749.[89]Ho-bum Lam, M., et al. (2009): High prevalence of hypokalemia in acute psychiatric inpatients. In: Gen Hosp Psychiatr. URL: https://www.sciencedirect.com/science/article/pii/S0163834309000425.
Potassium content of different meat products. (Graphic Source: Sparagna, 2019)
As such, it’s prudent to mind potassium levels throughout the diet. Some good animal-based potassium sources include milk, yogurt, tuna, salmon, and clams,[90]National Institute of Health. Potassium. URL: https://ods.od.nih.gov/factsheets/Potassium-HealthProfessional/. but food sources alone may not prevent deficiency.
Gut Health & Fiber
Many gut researchers have expressed concern over meat’s effects on the gut microbiome. These concerns may be valid, as a high-meat diet has shown to quickly change gut microbiome composition,[91]David, LA., et al. (2014): Diet rapidly and reproducibly alters the human gut microbiome. In: Nature. URL: https://www.nature.com/articles/nature12820. and high-fat diets correlate with increased disease risk.[92]Murphy, EA. / Velazquez, KT. / Herbert, KM. (2015): Influence of High-Fat-Diet on Gut Microbiota: A Driving Force for Chronic Disease Risk. In: Curr Opin Clin Nutr Metab Care. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4578152/.
Change of the microbiome after a plant or animal diet, sorted by clusters. Significant changes in intestinal colonisation as a result of a diet containing predominantly animal products are shown in orange. White circles = No change. Orange-green circles = a change in both a vegetable diet and an animal diet. (Picture source: David et al., 2014)
Thus, if you decide to go carnivore, it’s prudent to make sure that your diet isn’t too high in fat. For example, high dietary fat intake during a period of dietary change correlates with unfavorable changes in the gut[93]Murphy, EA. / Velazquez, KT. / Herbert, KM. (2015): Influence of High-Fat-Diet on Gut Microbiota: A Driving Force for Chronic Disease Risk. In: Curr Opin Clin Nutr Metab Care. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4578152/.[94]Le Leu, RK., et al. (2015): Butyrylated starch intake can prevent red meat-induced O6-methyl-2-deoxyguanosine adducts in human rectal tissue: a randomised clinical trial. In: Br J Nutr. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4531472/. (during overfeeding, at least).
That aside, gut health is not my area, so I’ll refer to RDN Sarah Ashman’s input here:
(…) low-carbohydrate/low-fiber diets see a rapid drop in short-chain fatty acid production, but also precipitous drops in Bifidobacteria, Roseburia, Faecalibacterium, and other [short-chain fatty acid] producers that require fermentable substrates. When we see those genera drop off too low, we also see increased translocation of endotoxin across the gut barrier and inflammation goes up systemically.”
AshmanTo support this claim, butyrate (short-chain fatty acid) deficiency in the colon seems to play a role in disease progression, via increased inflammation.[95]Scheppach, W., et al. (1992): Effect of butyrate enemas on the colonic mucosa in distal ulcerative colitis. In: Gastroenterol. URL: https://www.ncbi.nlm.nih.gov/pubmed/1612357.. Moreover, oral butyrate supplementation may help treat Crohn’s disease (digestive tract inflammation that causes abdominal pain, diarrhea, fatigue, and malnutrition).[96]Scarpellini, E., et al. (2007): Efficacy of butyrate in the treatment of diarrhoea-predominant irritable bowel syndrome. In: Dig Liv Dis Suppl. URL: https://www.sciencedirect.com/science/article/pii/S1594580408600066.[97]Di Sabatino, A., et al. (2005): Oral butyrate for mildly to moderately active Crohn’s disease. In: Aliment Pharmacol Ther. URL: https://www.ncbi.nlm.nih.gov/pubmed/16225487.
Ashman continues:
“Now, could someone eat like that and not see really overt symptoms for a while? Yes. Long term, no. But long term is relative to each person’s circumstances, going all the way to birth/early childhood acquired diversity and how adaptable their microbiome is to dramatic changes. It might take 5 weeks for one person to experience negative side effects or 5 years for someone else. There’s a ton of inter-individual variability.”
AshmanAs such, there may be reason for concern over gut health on a low-carbohydrate/fiber diet, with fiber intake of particular concern.[98]Parnell, JA. / Reimer, RA. (2012): Prebiotic fiber modulation of the gut microbiota improves risk factors for obesity and the metabolic syndrome. In: Gut Microbes. URL: https://www.ncbi.nlm.nih.gov/pubmed/22555633.
It‘s not only about butyrate, but also about fiber
Interestingly, research shows that fiber intake mitigates some of red meat’s ill effects on gut health, as fiber modulates the gut microbiota.[99]Le Leu, RK., et al. (2015): Butyrylated starch intake can prevent red meat-induced O6-methyl-2-deoxyguanosine adducts in human rectal tissue: a randomised clinical trial. In: Br J Nutr. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4531472/.[100]Parnell, JA. / Reimer, RA. (2012): Prebiotic fiber modulation of the gut microbiota improves risk factors for obesity and the metabolic syndrome. In: Gut Microbes. URL: https://www.ncbi.nlm.nih.gov/pubmed/22555633. In fact, increasing prebiotic fiber intake has shown to improve gut microbial balance,[101]Macfarlane, S. / Macfarlane, GT. / Cummings, JH. (2006): Review article: prebiotics in the gastrointestinal tract. In: Aliment Pharmacol Ther. URL: https://www.ncbi.nlm.nih.gov/pubmed/16918875. which may directly improve health.
Additionally, fiber consistently correlates with better health outcomes. To name a few, fiber correlates with lower risk of mortality,[102]Yang, Y., et al. (2015): Association between dietary fiber and lower risk of all-cause mortality: a meta-analysis of cohort studies. In: Am J Epidemiol. URL: https://www.ncbi.nlm.nih.gov/pubmed/25552267.[103]Kim, Y. / Je, Y. (2014): Dietary fiber intake and total mortality: a meta-analysis of prospective cohort studies. In: Am J Epidemiol. URL: https://www.ncbi.nlm.nih.gov/pubmed/25143474.[104]Kim, Y. / Je, Y. (2016): Dietary fibre intake and mortality from cardiovascular disease and all cancers: A meta-analysis of prospective cohort studies. In: Arch Cardiovasc Dis. URL: https://www.ncbi.nlm.nih.gov/pubmed/26711548. breast cancer,[105]Dong, JY., et al. (2011): Dietary fiber intake and risk of breast cancer: a meta-analysis of prospective cohort studies. In: Am J Clin Nutr. URL: https://www.ncbi.nlm.nih.gov/pubmed/21775566. gastric cancer,[106]Veronese, N., et al. (2018): Dietary fiber and health outcomes: an umbrella review of systematic reviews and meta-analyses. In: Am J Clin Nutr. URL: https://academic.oup.com/ajcn/article/107/3/436/4939351. esophageal cancer,[107]Veronese, N., et al. (2018): Dietary fiber and health outcomes: an umbrella review of systematic reviews and meta-analyses. In: Am J Clin Nutr. URL: https://academic.oup.com/ajcn/article/107/3/436/4939351. colon cancer,[108]Veronese, N., et al. (2018): Dietary fiber and health outcomes: an umbrella review of systematic reviews and meta-analyses. In: Am J Clin Nutr. URL: https://academic.oup.com/ajcn/article/107/3/436/4939351. renal cancer,[109]Veronese, N., et al. (2018): Dietary fiber and health outcomes: an umbrella review of systematic reviews and meta-analyses. In: Am J Clin Nutr. URL: https://academic.oup.com/ajcn/article/107/3/436/4939351. stroke,[110]Chen, GC., et al. (2013): Dietary fiber intake and stroke risk: a meta-analysis of prospective cohort studies. In: Eur J Clin Nutr. URL: https://www.ncbi.nlm.nih.gov/pubmed/23073261. obesity,[111]Slavin, JL. (2005): Dietary fiber and body weight. In: Nutr. URL: https://www.sciencedirect.com/science/article/pii/S0899900704003041. metabolic syndrome[112]Chen, JP., et al. (2018): Dietary Fiber and Metabolic Syndrome: A Meta-Analysis and Review of Related Mechanisms. In: Nutr. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5793252/. / type-2 diabetes,[113]Veronese, N., et al. (2018): Dietary fiber and health outcomes: an umbrella review of systematic reviews and meta-analyses. In: Am J Clin Nutr. URL: https://academic.oup.com/ajcn/article/107/3/436/4939351. high cholesterol,[114]Bazzano, LA. (2008): Effects of soluble dietary fiber on low-density lipoprotein cholesterol and coronary heart disease risk. In: Curr Atheroscler Rep. URL: https://www.ncbi.nlm.nih.gov/pubmed/18937894.[115]Gato, N., et al. (2013): Persimmon fruit tannin-rich fiber reduces cholesterol levels in humans. In: Ann Nutr Metab. URL: https://www.ncbi.nlm.nih.gov/pubmed/23171573.[116]Hwang, KA., et al. (2017): Cholesterol-lowering effect of astringent persimmon fruits (Diospyros kaki Thunb.) extracts. In: Food Sci Biotechnol. URL: https://www.ncbi.nlm.nih.gov/pubmed/30263533.[117]Arvill, A. / Bodin, L. (1995): Effect of short-term ingestion of konjac glucomannan on serum cholesterol in healthy men. In: Am J Clin Nutr. URL: https://www.ncbi.nlm.nih.gov/pubmed/7872224.[118]Whitehead, A., et al. (2014): Cholesterol-lowering effects of oat β-glucan: a meta-analysis of randomized controlled trials. In: Am J Clin Nutr. URL: https://www.ncbi.nlm.nih.gov/pubmed/25411276. and heart disease.[119]Bazzano, LA. (2008): Effects of soluble dietary fiber on low-density lipoprotein cholesterol and coronary heart disease risk. In: Curr Atheroscler Rep. URL: https://www.ncbi.nlm.nih.gov/pubmed/18937894.[120]McRae, MP. (2017): Dietary Fiber Is Beneficial for the Prevention of Cardiovascular Disease: An Umbrella Review of Meta-analyses. In: J Chiropr Med. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5731843/.
A fibre-rich diet contributes to a healthy and diverse intestinal flora. This dietary fibre serves as food for the intestinal bacteria, through which short-chain fatty acids (SCFAs) are synthesised. A typical Western diet (low fibre intake, high protein and sugar consumption) endangers this diversity, which affects SCFA production and adversely affects intestinal health. These short-chain fatty acids improve the mucosa, have an anti-microbial effect and increase the expression of the zonula (“tight junctions”). They also reduce oxygen levels and ensure an optimally functioning immune system, thus providing protection against infections. (Graphic Source: Makki et al., 2018)
Do we need fiber?
While fiber is not essential for survival, many suggest we need fiber for optimal health.[121]Kohn, JB. (2016): Is Dietary Fiber Considered an Essential Nutrient? In: J Academ Nutr Diet. URL: https://jandonline.org/article/S2212-2672(15)01743-8/abstract. All considered, while they’ll survive, carnivores probably lose out on health benefits seen with fiber.
Fiber has shown to increase satiety[122]Kolderup Hervik, A. / Svihus, B. (2019): The Role of Fiber in Energy Balance. In: J Nutr Metab. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6360548/.[123]Clark, MJ. / Slavin, JL. (2013): The effect of fiber on satiety and food intake: a systematic review. In: J Am Coll Nutr. URL: https://www.ncbi.nlm.nih.gov/pubmed/23885994. and reduce appetite,[124]Rao, TP. (2016): Role of guar fiber in appetite control. In: Physiol Behav. URL: https://www.ncbi.nlm.nih.gov/pubmed/27317834. which can promote weight loss[125]Kolderup Hervik, A. / Svihus, B. (2019): The Role of Fiber in Energy Balance. In: J Nutr Metab. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6360548/.[126]Thompson, SV., et al. (2017): Effects of isolated soluble fiber supplementation on body weight, glycemia, and insulinemia in adults with overweight and obesity: a systematic review and meta-analysis of randomized controlled trials. In: Am J Clin Nutr. URL: https://academic.oup.com/ajcn/article/106/6/1514/4823179.[127]Mayor, S. (2019): Eating more fibre linked to reduced risk of non-communicable diseases and death, review finds. In: BMJ. URL: https://www.bmj.com/content/364/bmj.l159. (a common goal among carnivores).
This considered, fiber is neutral for health at worst, and usually correlates with improved health. Additionally, eating fiber stimulates short-chain fatty acid production,[128]Chambers, ES., et al. (2018): Role of Gut Microbiota-Generated Short-Chain Fatty Acids in Metabolic and Cardiovascular Health. In: Curr Nutr Rep. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6244749/. which may play an important role in gut health.[129]Morrison, DJ. / Preston, T. (2016): Formation of short chain fatty acids by the gut microbiota and their impact on human metabolism. In: Gut Microbes. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4939913/.
Therefore, a diet that eliminates fiber is probably sup-optimal, and potentially harmful (although, research is limited here).
What about saturated fat & trans fat?
Although you might struggle to get enough fiber on a low-carb diet, it may be easy to eat too many saturated fats.
You see, saturated fats have shown to be more fattening than many other types of fat. Including polyunsaturated fats,[130]Rosqvist, F., et al. (2014): Overfeeding Polyunsaturated and Saturated Fat Causes Distinct Effects on Liver and Visceral Fat Accumulation in Humans. In: Diabetes. URL: http://diabetes.diabetesjournals.org/content/63/7/2356.long. monounsaturated fats,[131]Piers, LS., et al. (2003): Substitution of Saturated With Monounsaturated Fat in a 4-week Diet Affects Body Weight and Composition of Overweight and Obese Men. In: Br J Nutr. URL: https://www.ncbi.nlm.nih.gov/pubmed/13129479. and medium-chain triglycerides (MCTs).[132]Krotkiewski, M., et al. (2001): Value of VLCD Supplementation With Medium Chain Triglycerides. In: Int J Obes Relat Metab Disord. URL: https://www.ncbi.nlm.nih.gov/pubmed/11571605.
But further, just by swapping out saturated fats for other dietary fats, you can drop some fat[133]Piers, LS., et al. (2003): Substitution of Saturated With Monounsaturated Fat in a 4-week Diet Affects Body Weight and Composition of Overweight and Obese Men. In: Br J Nutr. URL: https://www.ncbi.nlm.nih.gov/pubmed/13129479.[134]Krotkiewski, M., et al. (2001): Value of VLCD Supplementation With Medium Chain Triglycerides. In: Int J Obes Relat Metab Disord. URL: https://www.ncbi.nlm.nih.gov/pubmed/11571605. and/or build more muscle.[135]Smith, GI., et al. (2011): Omega-3 Polyunsaturated Fatty Acids Augment the Muscle Protein Anabolic Response to Hyperinsulinaemia-Hyperaminoacidaemia in Healthy Young and Middle-Aged Men and Women. In: Clin Sci (Lond.) URL: https://www.ncbi.nlm.nih.gov/pubmed/21501117.[136]Smith, GI., et al. (2011): Dietary omega-3 Fatty Acid Supplementation Increases the Rate of Muscle Protein Synthesis in Older Adults: A Randomized Controlled Trial. In: Am J Clin Nutr. URL: https://www.ncbi.nlm.nih.gov/pubmed/21159787.[137]Tachtsis, B. / Camera, D. / Lacham-Kaplan, O. (2018): Potential Roles of n-3 PUFAs During Skeletal Muscle Growth and Regeneration. In: Nutrients. URL: https://www.ncbi.nlm.nih.gov/pubmed/29510597.[138]Jeromson, S., et al. (2015): Omega-3 Fatty Acids and Skeletal Muscle Health. In: Mar Drugs. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4663562/. That is, even when you eat the same amount of calories.
And what’s more: saturated fats have been shown to favor liver fat storage.[139]Leaf, A. / Antonio, J. (2017): The Effects of Overfeeding on Body Composition: The Role of Macronutrient Composition – A Narrative Review. In: Int J Exerc Sci. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5786199/.[140]Luukkonen, P., et al. (2018): Saturated Fat Is More Metabolically Harmful for the Human Liver Than Unsaturated Fat or Simple Sugars. In: Diabetes Care. URL: hattps://www.ncbi.nlm.nih.gov/pubmed/29844096.[141]Sobrecases, H., et al. (2010): Effects of Short-Term Overfeeding With Fructose, Fat and Fructose Plus Fat on Plasma and Hepatic Lipids in Healthy Men. In: Diabetes Metab. URL: https://www.ncbi.nlm.nih.gov/pubmed/20483648.[142]Sobrecases, H., et al. (2010): Effects of Short-Term Overfeeding With Fructose, Fat and Fructose Plus Fat on Plasma and Hepatic Lipids in Healthy Men. In: Diabetes Metab. URL: https://www.ncbi.nlm.nih.gov/pubmed/20483648. Which on its own, could be bad for your metabolic health.[143]Luukkonen, P., et al. (2018): Saturated Fat Is More Metabolically Harmful for the Human Liver Than Unsaturated Fat or Simple Sugars. In: Diabetes. URL: https://www.ncbi.nlm.nih.gov/pubmed/29844096.[144]Paschos, P. / Paletas, K. (2009): Non alcoholic fatty liver disease and metabolic syndrome. In: Hippokratia. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2633261/.
But as bad as saturated fat can be, trans fats appear to be worse for you. Since many studies show that eating more trans fat correlates with higher risk of heart disease,[145]Zaloga, GP., et al. (2006): Trans Fatty Acids and Coronary Heart Disease. In: Nutr Clin Pract. URL: https://www.ncbi.nlm.nih.gov/pubmed/16998148. infertility,[146]Chavarro, J., et al. (2007): Dietary fatty acid intakes and the risk of ovulatory infertility. In: Am J Clin Nutr. URL: https://www.researchgate.net/publication/6592463_Dietary_fatty_acid_intakes_and_the_risk_of_ovulatory_infertility. and diabetes[147]Micha, R. / Mozaffarian, D. (2009): Trans fatty acids: effects on metabolic syndrome, heart disease and diabetes. In: Nat Rev Endocrinol. https://www.nature.com/articles/nrendo.2009.79. (among other health detriments[148]Mozaffarian, D. / Aro, A. / Willett, WC. (2009): Health effects of trans-fatty acids: experimental and observational evidence. In: Eur J Clin Nutr. URL: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.952.3166&rep=rep1&type=pdf.). Plus, you don’t even need any trans fat for bodily function.[149]EFSA (2010): Scientific Opinion on Dietary Reference Values for fats, including saturated fatty acids, polyunsaturated fatty acids, monounsaturated fatty acids, trans fatty acids, and cholesterol. URL: http://onlinelibrary.wiley.com/doi/10.2903/j.efsa.2010.1461/epdf. So all told, to play it safe, you should minimize trans fat intake.
Now here’s the bottom line: If you want to lose fat and max out health, you should eat less saturated and trans fat. Especially if they come from processed foods.
Cancer
In part given its effects on the gut,[150]Le Leu, RK., et al. (2015): Butyrylated starch intake can prevent red meat-induced O6-methyl-2-deoxyguanosine adducts in human rectal tissue: a randomised clinical trial. In: Br J Nutr. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4531472/. red meat consumption has been linked to cancer. More specifically, red meat (e.g. beef or lamb[151]Carr, PR., et al. (2015): Meat subtypes and their association with colorectal cancer: Systematic review and meta‐analysis. In: Internat J Canc. URL: https://onlinelibrary.wiley.com/doi/full/10.1002/ijc.29423.) consistently correlates with increased risk of colorectal, prostate, pancreatic, gastric, breast, bladder, and head-and-neck cancer[152]Zhao, Z., et al. (2017): Red and processed meat consumption and colorectal cancer risk: a systematic review and meta-analysis. In: Oncotarget. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5669970/.[153]Chan, DS., et al. (2011): Red and processed meat and colorectal cancer incidence: meta-analysis of prospective studies. In: PLoS One. URL: https://www.ncbi.nlm.nih.gov/pubmed/21674008.[154]Alexander, DD., et al. (2010): A review and meta-analysis of prospective studies of red and processed meat intake and prostate cancer. In: Nutr J. URL: https://www.ncbi.nlm.nih.gov/pubmed/21044319.[155]Zhao, Z., et al. (2017): Association Between Consumption of Red and Processed Meat and Pancreatic Cancer Risk: A Systematic Review and Meta-analysis. In: Clin Gastroenterol Hepatol. URL: https://www.cghjournal.org/article/S1542-3565(16)30854-0/fulltext.[156]Kim, SR., et al. (2019): Effect of Red, Processed, and White Meat Consumption on the Risk of Gastric Cancer: An Overall and Dose–Response Meta-Analysis. In: Nutrients. URL: https://www.mdpi.com/2072-6643/11/4/826.[157]Alexander, DD., et al. (2010): A review and meta-analysis of red and processed meat consumption and breast cancer. In: Nutr Res Rev. URL: https://www.ncbi.nlm.nih.gov/pubmed/21110906.[158]Crippa, A., et al. (2018): Red and processed meat consumption and risk of bladder cancer: a dose–response meta-analysis of epidemiological studies. In: Eur J Nutr. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5845591/.[159]Perloy, A., et al. (2017): Intake of meat and fish and risk of head–neck cancer subtypes in the Netherlands Cohort Study. In: Cancer Causes Control. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5400785/. Moreover, red meat intake is positively associated with all-cause mortality.[160]Larsson, SC. / Orsini, N. (2014): Red meat and processed meat consumption and all-cause mortality: a meta-analysis. In: Am J Epidemiol. URL: https://www.ncbi.nlm.nih.gov/pubmed/24148709.[161]Schwingshackl, L., et al. (2017): Food groups and risk of all-cause mortality: a systematic review and meta-analysis of prospective studies. In: Am J Clin Nutr. URL: https://academic.oup.com/ajcn/article/105/6/1462/4569801.) heart disease,[162]Key, TJ., et al. (2019): Consumption of Meat, Fish, Dairy Products, and Eggs and Risk of Ischemic Heart Disease. A Prospective Study of 7198 Incident Cases Among 409 885 Participants in the Pan-European EPIC Cohort. In: Circulation. URL: https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.118.038813. and stroke,[163]Yang, C., et al. (2016): Red Meat Consumption and the Risk of Stroke: A Dose-Response Meta-analysis of Prospective Cohort Studies. In: J Stroke Cerebrovasc Dis. URL: https://www.ncbi.nlm.nih.gov/pubmed/26935118. as well as non-hodgkin lymphoma and multiple myeloma.[164]Caini, S., et al. (2016): Food of animal origin and risk of non-Hodgkin lymphoma and multiple myeloma: A review of the literature and meta-analysis. In: Crit Rev Oncol Hematol. URL: https://www.sciencedirect.com/science/article/pii/S104084281630035X.
As such, disease risk and early death are long-term concerns on a red meat-heavy diet.
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Probability of developing cancer by cancer type and with unprocessed and processed red meat consumption. (Graphic Source: Myoleanfitness.com)
To mitigate disease risk, eat no more than 500 grams of red meat per week. If you’re going to eat red meat, try to avoid charred red meat, or that with visible fat.[165]Bronzato, S. / Durante, A. (2017): A Contemporary Review of the Relationship between Red Meat Consumption and Cardiovascular Risk. In: Int J Prev Med. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5474906/. Otherwise, aim to eat fruits, vegetables, or spices alongside red meat. But lastly, and most importantly, you should maintain a proper lifestyle; with adequate sleep, low stress, regular physical activity, healthy body weight, and few harmful behaviors. Doing that makes a much bigger impact on healthspan than red meat can.
Luckily, poultry and fish usually correlate negatively with disease risk, so carnivores can eat these meats with little worry. Plus, while it’s considered a red meat, pork may not increase disease risk as much as beef or lamb.
For instance, in a 2016 review of 42 meta-analyses, beef correlated with increased cancer risk, but pork didn’t.[166]Lippi, G. / Mattiuzzi, C. / Cervellin, G. (2016): Meat consumption and cancer risk: a critical review of published meta-analyses. In: Crit Rev Oncol Hemtaol. URL: https://www.sciencedirect.com/science/article/pii/S1040842815300780. As such, carnivores should eat mostly poultry or fish, and opt for pork if forced to eat red meat.
Diet Sustainability
Unfortunately, no research has examined the adherence to the carnivore diet over time. However, the ketogenic diet is much like a carnivore diet, as it restricts carbohydrates, includes many animal foods, blunts appetite, and induces a state of ketosis. Fortunately, adherence to the ketogenic diet has been researched extensively.[167]Tzur, A., et al. (2018): Adhering to the Ketogenic Diet – Is it Easy or Hard? In: Sci-Fit.net URL: https://sci-fit.net/adhere-ketogenic-diet/.
Ultimately, while people are no more likely to drop out of a ketogenic diet study than a low-fat diet study, long-term adherence to keto is rare. Indeed, a thorough analysis of the ketogenic diet literature suggests that few people can maintain such a diet for over 14 weeks.[168]Gibson, AA. / Sainsbury, A. (2017): Strategies to Improve Adherence to Dietary Weight Loss Interventions in Research and Real-World Settings. In: Behav Sci. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5618052/.
This may be because so many foods are high in carbohydrates,[169]Gibson, AA. / Sainsbury, A. (2017): Strategies to Improve Adherence to Dietary Weight Loss Interventions in Research and Real-World Settings. In: Behav Sci. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5618052/. and diets that restrict foods tend to be less successful. For example, Loria-Kohen et al. showed that diets with and without bread led to similar weight loss:[170]Loria-Kohen, V., et al. (2012): Evaluation of the usefulness of a low-calorie diet with or without bread in the treatment of overweight/obesity. In: Clin Nutr. URL: https://www.ncbi.nlm.nih.gov/pubmed/22209501.
In the adherence test, 60.4% stated that they were“adherent”, which provided an average score of 23.94. ± 4 points for the test. If we compare the results of the test for both groups, the percentage of those adhering was greater in the BREAD group than in the NOBREAD group (64.3% vs. 55.6%), although the differences in thescores for the full questionnaire or by question were not significant. Of the volunteers included in the study (61 in each group), 17 dropped out during the study (13.9%). The NO BREAD group had the most dropouts (21.3% vs. 6.6%, P<0.05).
Loria-Kohen et al., 2012However, despite losing no less weight, the group excluding bread reported more transgressions from the diet plan, and more subjects from the group without bread dropped out of the study. In other words, those restricting bread (a high-carb food) were more likely to “cheat” on, or even quit their diets.
Indeed, this is seemingly supported by other research, which indicates that those who diet more strictly on the weekends are actually more likely to regain weight.[171]Jorge, R., et al. (2019): Does diet strictness level during weekends and holiday periods influence 1-year follow-up weight loss maintenance? Evidence from the Portuguese Weight Control Registry. In: Nutr J. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6330473/.
Moreover, those who diet “rigidly” experience less diet success, more food focus, higher body fat levels, more frequent overeating episodes, worse mood, and poor body image, among other bad outcomes[172]Westenhoefer, J. / Stunkard, AJ. / Pudel, V. (1999): Validation of the flexible and rigid control dimensions of dietary restraint. In: Int J Eat Disord. URL: https://www.ncbi.nlm.nih.gov/pubmed/10349584.[173]Schaumberg, K., et al. (2016): Dietary restraint: what’s the harm? A review of the relationship between dietary restraint, weight trajectory and the development of eating pathology. In: Clin Obes. URL: https://www.ncbi.nlm.nih.gov/pubmed/26841705.[174]Smith, CF., et al. (1999): Flexible vs. Rigid dieting strategies: relationship with adverse behavioral outcomes. In: Appetite. URL: https://www.ncbi.nlm.nih.gov/pubmed/10336790.[175]Stewart, TM. / Williamson, DA. / White, MA. (2002): Rigid vs. flexible dieting: association with eating disorder symptoms in nonobese women. In: Appetite. URL: https://www.ncbi.nlm.nih.gov/pubmed/11883916. Yet, those who adopt more “flexible” mindsets to dieting are more likely to maintain weight loss.[176]Westenhoefer, J., et al. (2004): Behavioural correlates of successful weight reduction over 3 y. Results from the Lean Habits Study. In: Int J Obes Relat Metab Disord. URL: https://www.ncbi.nlm.nih.gov/pubmed/14647175.
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Which factors are decisive for successful weight reduction and subsequent weight maintenance (over a period of 3 years) (Vs. no success)? This information is provided by the odds ratio. It is shown that a flexible approach (“Flexible control of eating”) improves the odds more than a rigid control (“Rigid control of eating”). However, the meal rhythm and food choice also play a role that should not be underestimated. (Graphic Source: Westenhoefer et al., 2003)
As such, those who restrict specific foods or macronutrients often fare poorly on diets, as compared to those who view dieting flexibly. Hence, carnivores may struggle to stick to the diet over time, because they’re going to diet rigidly; restricting many foods.
Psychological Health
As mentioned, rigid dieting correlates with many poor psychological outcomes. Specifically for those seeking weight loss, this presents a potential red flag.
For example, research shows that rigid dieters are the most likely to experience disordered eating and poor body image,[177]Linardon, J. / Mitchell, S. (2017): Rigid dietary control, flexible dietary control, and intuitive eating: Evidence for their differential relationship to disordered eating and body image concerns. In: Eat Behav. URL: https://www.researchgate.net/publication/312593792_Rigid_dietary_control_flexible_dietary_control_and_intuitive_eating_Evidence_for_their_differential_relationship_to_disordered_eating_and_body_image_concerns. which can lead to low self-esteem, depressive symptoms, anxiety, drug abuse, interpersonal problems, and even suicidal thoughts.[178]Linardon, J. (2019): The Ultimate List of Body Image Statistics. In: BreakingBingeEating.com. URL: https://breakbingeeating.com/body-image-statistics/.
While carnivores aren’t necessarily more likely to experience disordered eating, dieting is a primary risk factor for disordered eating and poor body image.[179]NEDA: What are eating disorders? Risk factors. URL: https://www.nationaleatingdisorders.org/risk-factors.[180]NEDA: Body Image. URL: https://www.nationaleatingdisorders.org/body-image-0. As such, adopting a carnivore diet with the intent to lose weight, increase your risk of psychological stress and overeating (if not an eating disorder). Therefore, those with histories of dieting, poor body image, or disordered eating should probably avoid restrictive diets, the carnivore diet included.
Conclusion
All considered, the carnivore diet has many benefits, so it often works. Ethics aside,[181]Deckers, J. (2016): Animal (De)liberation: Should the Consumption of Animal Products Be Banned? URL: https://www.ncbi.nlm.nih.gov/books/NBK396516/. this diet provides a useful tool for (short-term) fat loss, because it can promote low energy intake and good eating habits.
This is great, since fat loss alone can quickly improve health((Bilger, M., et al. (2013): The Effect of Weight Loss on Health, Productivity and Medical Expenditures among Overweight Employees. In: Med Care. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3654027/. and appearance. Yet, carnivores may risk nutrient deficiency or other health issues in the long run (e.g. increased cancer risk or poor gut health).
Practically, while you probably shouldn’t go carnivore, it’s worth noting “the good” in the carnivore diet. To maintain fitness for a lifetime, your diet should provide many of the mentioned benefits.
Limitations
The carnivore diet has not been researched directly, so some of the above claims are necessarily speculative.
Title Image Source: Fotolia / Anton
References
