By Sten van Aken | Reading Time: 12 minutes |

Whether your main goal is weight-loss, weight maintenance or weight-gain, one can go about setting up a diet in various ways in order to achieve the desired bodyweight.

Although a large majority of readers probably employs some form of Calorie-tracking on their own and/or for their clients, it might be difficult or look seemingly impossible to even consider how one could still reach weight-related goals without tracking your calories.

Indeed, what if counting calories isn’t an option?

Is there still a reliable method to go by that doesn’t compromise every goal you throw at it? Perhaps something that isn’t as accurate as tracking your calories, but still a lot better than to be ending up following restrictive diets?

What if we want to loosen things up in order to focus on other important things? Perhaps we want to stay relatively healthy and fit without too much effort instead of staying at non-sustainable levels of bodyfat throughout the year. Is that even realistic and attainable without tracking your calories?

In this article we’re going to cover the side of dieting that doesn’t involve tracking your calories and relies heavily on characteristics we already possess whether we know it or not: ad libitum dieting.

Ad Libitum Dieting I: From Biology to Practice

Ad libitum: Eat as much as you want?

Ad libitum dieting is defined as ‘(eating) at one’s own pleasure, or as much as one desires, or to the full extent of one’s wishes.’

Yes, you read that right. Ad libitum at face value appears to be almost everything most modern diets are not: as much as you desire. But before we immediately conclude this article and leave it at that, there is more than what meets the eye.

Ad libitum dieting isn’t dieting defined by a particular caloric intake that makes up a food pattern. Rather, it is more how most of us (used to) go about eating. It namely is an attitude towards eating.

Why write about ad libitum dieting?

Well, for one it is the attitude towards eating that has defined and sustained us for thousands of years when there was no such thing as tracking calories and thus is at least worth our attention as people who care about nutrition and behavior.

But more importantly, this attitude towards dieting has taught us a lot about the relationship with food that nature has equipped us with and how us humans are similar and different in a lot of ways compared to other biological species.

There are many people out there who have already made their attempts with intuitive eating and failed. Therefore many of us – loosely based on the saying “trust is good, control is better” – use a certain form of calorie tracking to be on the safe side. Does this mean that we have to or should count calories for the rest of our lives? (Image Source: Fotolia / asiandelight)

Finally, ad libitum dieting can be especially reliable in those that have prior experience with tracking calories for more than a year and have lost, maintained and/or gained weight over this period, making it a suitable method for those looking to sustain their goals in the long run.

To fully grasp the significance of this attitude and to understand the quite literal nature of ad libitum dieting, we have to start from the beginning and go back in time where there was no such thing as tracking your calories.

The origin of ad libitum dieting: distinctions and similarities between species

The Latin words “ad libitum” can refer to a variety of attitudes towards things in different fields. For example, in modern medicine you can observe that medical prescriptions may use the abbreviation ad lib. to indicate that one is ‘freely’ allowed to take that drug. Another example would be a patient that needs to fast overnight, where the doctor’s order might read ‘’water ad lib’’ and thus as desired.

When spoken about in the study of biology and nutrition, however, ad libitum is generally used to describe unrestricted behavioral eating patterns of biological species. This includes us, human-animals, but also non-human animals such as rodents.

The fact that ad libitum is used to describe all patterns of unrestricted behavioral eating in all biological species might indicate that there is large variety amongst organisms. But the same complexity also provides order, in that we get a clear separation between what is common across and between biological species and what isn’t, as well as what substitutes the basis for all self-sustaining biological species on earth.^[1]Wynne-Edwards, VC. (1965): Self-Regulating Systems in Populations of Animals. In: Sci. URL: https://science.sciencemag.org/content/147/3665/1543.

To explore these commonalities and differences, we’re first going to investigate those that we study the most as models for ourselves to learn more about ad libitum dieting: rodents, in particular rats.

Why rodents are the perfect study subjects

Rats are typically held in isolated cages and fed a standardized ad libitum diet. This diet, which mostly consists of chow, provides rats with a mixed type of feed that consists of carbohydrates, fats and proteins.^[2]Warden, CH. / Fisler, JS. (2008): Comparisons of diets used in animal models of high-fat feeding. In: Cell Metab. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2394560/.

But there’s a catch to this ad libitum chow diet and why it has become the universal standard diet. When rats are given ad libitum access to this particular feed, they neither gain nor lose any weight.^[3]Martire, SI., et al. (2013): Altered feeding patterns in rats exposed to a palatable cafeteria diet: increased snacking and its implications for development of obesity. In: PLoS One. URL: https://www.ncbi.nlm.nih.gov/pubmed/23565243.

Average food consumption (within a 24-hour period in grams, far left), energy intake in kilojoules (center), and changes in body weight within a 16-week period in 7-8-week-old rats fed either a standardized diet (Chow = Ch, white circles) or a typical Western diet (Cafeteria Diet = Caf, black squares). (Image Source: Martire et al., 2013)

Thus, they rely exclusively on their system telling them when to eat and when not to, even in the face of a variety of factors that alter their energy needs, such as fluctuating levels of physical activity or due to small and larger phenotypical differences.^[4]4 And thinking about it, in the face of millions of years of evolution, the fact that biological species are able to achieve that balance comes as no surprise.

The same standardized diet also makes rats in the context of ad libitum dieting excellent models for seeing the effects of various diets and/or activity levels, since you can feed one group something that keeps them in balance under all circumstances (control), where feeding something different to another group might lead to a different outcome (test group).^[5]Warden, CH. / Fisler, JS. (2008): Comparisons of diets used in animal models of high-fat feeding. In: Cell Metab. URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2394560/.^[6]Martire, SI., et al. (2013): Altered feeding patterns in rats exposed to a palatable cafeteria diet: increased snacking and its implications for development of obesity. In: PLoS One. URL: https://www.ncbi.nlm.nih.gov/pubmed/23565243.^[7]Smyers, ME., et al. (2015): Physically active rats lose more weight during calorie restriction. In: Physiol Behav. URL: https://www.ncbi.nlm.nih.gov/pubmed/25449411.

Rodents that are fed a diet that mimics the typical Western diet (cafeteria diet) develop overweight and a pathological fatty liver, unlike their counterparts that are fed a standardized rodent diet. (Graphic Source: Maeda Júnior et al., 2018)

…and why humans are a difficult species to study

If we were to look at ourselves from an objective biological perspective, our natural attitude towards dieting looks very similar to that of rodents and other biological species.

Humans naturally eat in episodes (i.e. snacks and meals) until they’re comfortably full (satiation), after which they do not eat for an extended amount of time (satiety). After that, an ever-increasing drive and motivation guides their eating behavior (hunger/appetite), which in turn determines their next eating episode.^[8]de Graaf, C., et al. (2004): Biomarkers of satiation and satiety. In: Am J Clin Nutr. URL: https://www.ncbi.nlm.nih.gov/pubmed/15159223.

Selection of potential markers that play a prominent role in the satiety. (Graphic Source: De Graaf et al., 2004)

Thus, judging objectively, a major part of our natural daily tendencies towards foods are to ensure that we self-sustain ourselves and meet adequate energy demands just like most biological species.

But this view also has some limitations in that we are, surprise, human. Indeed, the 21^st century for humans provides a different environment than a rat trapped in an isolated cage. Self-sustainability is, to say the very least, challenging in our current environment, because we’re often tempted to eat for reasons other than for our biological need.

Furthermore, we’re also complicated by the fact that we come with more unpredictable patterns and are more subject to internal and external factors. For example, humans can eat more than they normally would for a variety of other reasons than for our biological need, including social reasons,^[9]Higgs, S. (2015): Social norms and their influence on eating behaviours. In: Appetite. URL: https://www.ncbi.nlm.nih.gov/pubmed/25451578. sensory purposes such as sight or smell ^[10]Cornell, CE. / Roding, J. / Weingarten, H. (1989): Stimulus-induced eating when satiated. In: Physiol Behav. URL: https://www.ncbi.nlm.nih.gov/pubmed/2780836. or even as a coping strategy to relieve stress or reduce boredom.^[11]Moynihan, AB., et al. (2015): Eaten up by boredom: consuming food to escape awareness of the bored self. In: Front Psychol. URL: https://www.ncbi.nlm.nih.gov/pubmed/25883579.^[12]Newman, E., et al. (2007): Daily hassles and eating behaviour: the role of cortisol reactivity status. In: Psychoeuroendocrinology. URL: https://www.ncbi.nlm.nih.gov/pubmed/17198744..

In contrast to other biological species, we humans do not eat only to satisfy our hunger and energy needs. To make matters worse, we live in an environment that promotes increased calorie intake. (Image Source: Fotolia / luckybusiness)

But perhaps the biggest reason why we are a hard species to study objectively has to do with our inability to act like ourselves in the presence of others like we would if we were home. For example, when humans are studied in a laboratory environment, they typically behave differently than they would naturally, since they’re aware of being observed and (un)consciously change their natural behavior, also described as the Hawthorne effect^[13]Robinson, E., et al. (2016): The effect of heightened awareness of observation on consumption of a multi-item laboratory test meal in females. In: Physiol Behav. URL: https://www.ncbi.nlm.nih.gov/pubmed/27137078..

Given the variety of commonalities and differences between non-human animals and human-animals, how can we look and understand ad libitum dieting in the 21^st century in such a way that we separate the wheat from the chaff?

Ad libitum dieting in the 21^st century

To understand ad libitum dieting, we also have to understand the context in which it can be used in dieting to avoid confusion. Since ad libitum dieting is an attitude towards dieting rather than a particular set of rules, the intent can change depending on the application and can sometimes lead to confusion.

For example: Lots of (fad) diets use the ad libitum attitude towards eating without explicitly stating so. Atkins, South-Beach and Paleo are all diets defined by a particular set of rules, which prohibit you from consuming certain food groups, individual foods and/or individual nutrients, while although not always explicitly mentioned, ad libitum access to what’s left after restriction.

Thus, the fact that these diets mostly base their restrictions on cherry picked science doesn’t invalidate the ad libitum attitude towards eating. It simply means that these restrictions work for the wrong reasons. This is complicated by the fact that if one were asked what type of diet is best, most would reply that the diet that is best is the one that is most sustainable for a person or (large) group of people. For some that would mean tracking your calories and being less restrictive, while for others, solely having restrictions would provide a lot of structure and make it easier to follow.

Many popular diets rely on the ad libitum principle without explicitly mentioning it. This means that certain food groups, individual foods or nutrients are eliminated. What remains can be eaten until you feel full and satisfied. But what is actually important here? (Image Source: Fotolia / BurntRedHen)

Indeed, this is in accordance with research from Senior et al showing that there is large inter-individual variation in weight loss between those that lose weight on an ad libitum diet vs. those that solely restrict calories^[14]Senior, AM., et al. (2016): Meta-analysis of variance: an illustration comparing the effects of two dietary interventions on variability in weight. In: Evol Med Public Health. URL: https://www.ncbi.nlm.nih.gov/pubmed/27491895..

Other research by both researcher Hall and Heymsfield et al has highlighted that although standard interventions that employ caloric restriction almost inevitably lead to weight-loss, they are rarely able to sustain long-term weight loss in people.^[15]Hall, KD. (2010): Predicting metabolic adaptation, body weight change, and energy intake in humans. In: Am J Physiol Endocrinol Metab. URL: https://www.ncbi.nlm.nih.gov/pubmed/19934407.^[16]Heymsfield, SB., et al. (2007): Why do obese patients not lose more weight when treated with low-calorie diets? A mechanistic perspective. In: Am J Clin Nutr. URL: https://www.ncbi.nlm.nih.gov/pubmed/17284728..

Finally, research conducted by Olson & Emery and Dombrowski found that interventions that rely less on numbers and more on feelings showed to be less successful for losing weight in the short-term, but increasing the success at which people are able to sustain long-term weight loss.^[17]Olson, KL. / Emery, CF. (2015): Mindfulness and weight loss: a systematic review. In: Psychosom Med. URL: https://www.ncbi.nlm.nih.gov/pubmed/25490697.^[18]Dombrowski, SU., et al. (2014): Long term maintenance of weight loss with non-surgical interventions in obese adults: systematic review and meta-analyses of randomised controlled trials. In: BMJ. URL: https://www.ncbi.nlm.nih.gov/pubmed/25134100.

Indeed, these (fad) diets are effective for the wrong reasons and miss the underlying reason why ad libitum dieting can be successful.

The best way to illustrate this underlying reason is illustrated by a study done by Jonsson et al (2010) comparing an ad libitum Paleo diet vs. an ad libitum Mediterranean-like diet and found that despite a significantly larger energy deficit in the Paleolithic group (ad libitum energy intake of 1385 kcal vs. 1815 kcal in the Mediterranean-like diet), the Paleolithic diet was more satiating per Calorie than the Mediterranean-like ad libitum diet.^[19]Jönsson, T., et al. (2010): A paleolithic diet is more satiating per calorie than a mediterranean-like diet in individuals with ischemic heart disease. In: Nutr Metab (Lond). URL: https://www.ncbi.nlm.nih.gov/pubmed/21118562.^[20]Jönsson, T., et al. (2013): Subjective satiety and other experiences of a Paleolithic diet compared to a diabetes diet in patients with type 2 diabetes. In: Nutr J. URL: https://www.ncbi.nlm.nih.gov/pubmed/23890471..

Satiety per kilocalorie in a Paleo diet (o) and a Mediterranean diet (•) depending on the fibre intake (A), protein intake (B) and energy density of the diet (C). (Graphic Source: Jönsson et al., 2010)

This study is a clear example of how restriction of certain food groups, individual foods and/or individual nutrients can lead to large energy differences between different ad libitum diets. But more importantly, the same study also shows that the ability to impact feelings of hunger, satiety and satiation has a lot less to do with your daily caloric intake and a lot more with how we can eat food that offers greater satiety per unit of energy.

The same researchers later did a re-analysis of the data to further elucidate the mechanisms behind these effects and found that only the levels of plasma leptin were significantly associated with the ad libitum Paleolithic diet, while finding no significant differences between diets for fasting plasma concentrations of glucagon, insulin, incretins, ghrelin, C-peptide and adipokines.^[21]Fontes-Villalba, M., et al. (2016): Palaeolithic diet decreases fasting plasma leptin concentrations more than a diabetes diet in patients with type 2 diabetes: a randomised cross-over trial. In: Cardiovasc Diabetol. URL: https://www.ncbi.nlm.nih.gov/pubmed/27216013.

Thus, the differences in outcomes between the two diets can’t solely be attributed to changes in levels of hormones. The researchers then went on to conclude that the significant effect on plasma leptin and slightly impacting the levels of plasma glucagon was likely to be the primary explanation to the findings, and that deviating from the Paleolithic diet would be detrimental to these hormones.

Leptin & glucagon fasting hormone levels after a 3-month paleo diet (n=7) or a diet designed according to current diabetes guidelines (n=6). Significant results were marked with an asterisk (*) (p < 0.05). NS = Not significant. (Graphic Source:: Jönsson et al., 2016)

The researchers are, however, missing the forest for the trees. Just like insulin is blamed for the inability to lose weight during a diet, we’re wrong in concluding that it is the low insulin that is driving the weight loss success of these low-carb ad libitum diets. For this same reason and this time in a positive fashion, plasma leptin and glucagon concentrations are incorrectly characterized as the hormones responsible for the success of the Paleolithic ad libitum diet.

Summary

Humans like any other biological species living on this planet have relied on their system telling them when to eat and when not to for thousands of years. Due to the complexity of our human nature and our environment, eating for reasons other than our biological need is almost inevitable. But even in spite of these differences and similarities between us and other biological species, as well as the unique 21^st century we live in, there is still a lot to be learned about our behavior that can aid us in our dietary behavior to develop more successful diets.

What drives successful dieting in the long run for a large group of people appears to have a lot less to do with calories or restrictions and a lot more with the ability of a diet to manipulate dietary variables in such a way that satiety and satiation are maximized and feelings of hunger minimized. But although that may be true, that does leave a couple of unanswered questions that are worth answering in the next article.

What is the exact dietary basis for ad libitum dieting and how do we determine whether we or our clients are sufficiently prepared to let go of counting numbers and instead rely more on our feelings?

Furthermore, what are scientifically validated strategies and ways of reliably resonating with our feelings that we can employ in an ad libitum fashion of dieting that further builds on the principles of maximizing the satiating effectiveness of the approach, as well as help adhering to the diet?

In the next part I will guide you through an analogy and provide you with a thorough overview of dietary strategies that help you successfully follow the ad libitum attitude towards dieting for both yourself as well as for your clients.

Title Image Source: Fotolia / diignat