Paper: Dulloo, A. G., Jacquet, J., & Montani, J. P. (2012). How dieting makes some fatter: from a perspective of human body composition autoregulation. Proceedings of the Nutrition Society, 71(3), 379-389.
One of things I aim to do through this blog is to raise awareness amongst nutrition professionals on the long-term side effects that restrictive dieting causes. Many evidenced-based nutritionists know a lot about nutrition but there is a lack of awareness in the health and fitness industry on the emerging evidence around intuitive eating and a non-diet approach to healthy weight maintenance and overall health.
Dulloo et al’s (2012) research was brought to my attention in a soon-to-be published paper by Kärkkäinen et al (2018)* looking at factors associated with successful weight maintenance over ten years. This paper highlights how successful weight maintenance in both men and women was associated with regular eating and having NO history of dieting, supporting the non-diet paradigm. Kärkkäinen cites Dulloo et al’s (2012) research when discussing dieting as a predictor of weight gain so I felt it was important to explore this research further and share it’s implications.
Dulloo et al’s paper reviews longitudinal studies on starvation and re-feeding as well as re-analyses the data from the Minnesota Starvation Study.
- Dieting in healthy weight individuals increases the risk of long-term weight gain and cardiometabolic risk factors. This is not the case in obese individuals.
- Studies indicate that one-third to two-third of dieters regain the weight lost within one year and almost 100% regain the lost weight within five years.
- One third of dieters regain more weight than they lost.
- There is a dose dependant relationship between dieting, BMI and risk of being overweight. One weight loss attempt before the age of 25 doubles the risk of being overweight at age 25. Multiple weight loss attempts increases the risk of being overweight by fivefold at age 25.
- Male athletes who weight cycle (go through several dieting cycles in weight-related sports like boxing, powerlifting, bodybuilding…) have an increased BMI of 5.2 units by age 60 compared to age 20 compared to those who have an athletic background but without the weight focus where there is an increase of only 3.3 units. This highlights the risk dieting as a young adult causes in middle age.
- Twin studies show a genetic component to obesity and a genetic component to the likelihood of dieting. They also show that dieting may promote weight gain independent of genetics.
- Individuals who are already lean when they restrict food intake (diet!) end up regaining an extra 4kg during nutritional rehabilitation due to fat overshooting (see below).
This is common in restrictive dieting and refers to where, after a period of restrictive dieting and weight loss, more fat is regained than was originally lost (often the cause/result of yo-yo dieting).
- The Swiss Food Rationing Experiment studied 700 people undergoing rationing in Switzerland between 1941 and 1946. As soon as the rationing was lifted, there was an average 6.5kg of fat overshooting (people ended up around 6.5kg heavier than when the rationing started).
- In the Minnesota Starvation Experiment 32 males went through 24-weeks of semi-starvation and 8 weeks re-feeding to explore nutritional rehabilitation. Participants lost 25% of their body weight on average during the 24 weeks. Once the semi-starvation phase was over (this can be viewed as the equivalent to dieting in current society), and the participants had 8 weeks of unrestricted eating, they were on average 3.3kg heavier than when the study began (with a lot of food and body issues too).
- Military training studies show that after a period of training involving food restriction and a high level of activity, military personnel lost around 12% of their body weight. After 5 weeks of unrestricted eating, they were on average 5kg heavier than when the training began.
Hyperphagia is excessive hunger and is extremely common in those following restrictive diets, those who have lost weight and are now trying to maintain that weight loss, and those in recovery from eating disorders.
- Excessive hunger is still present when fat mass is 100% of what is was before weight was lost and does not reduce until 100% of fat free mass is restored. As fat free mass takes longer to recover than fat mass, this is why dieting causes people to gain more weight than they lost and why those in recovery from anorexia nervosa may initially experience an increase in fat gain before body composition is more evenly distributed (it can be helpful to inform those going through anorexia about this to help them cope with changes in their body and appetite).
- There are individual differences in how weight gain is re-distributed in terms of fat mass and fat free mass. The higher the body fat initially, the more fat is deposited during weight gain.
- Reanalysis of the data from the Minnesota Starvation experiment highlighted that fat depletion, lean body mass depletion, and restricted energy intake were predictors of excessive hunger
- Excessive hunger continues until body composition is restored (both fat and lean body mass) – see below
This is a metabolic, behavioural, neuroendocrine, and autonomic responses designed to maintain body energy stores (fat) at a level the central nervous systems defines as “ideal” for that individual. This is why it is often difficult to maintain weight loss long-term – the body wants to go back to it’s before-dieting baseline.
- Adaptive thermogensis (often referred to as reduced metabolic rate) is determined by the extent of the energy deficit and the level of body fat depletion.
- Reduction in basal metabolic rate (BMR) during weight loss is usually 10-15%
- There are two control systems responsible for adaptive thermogensis 1. Food intake and energy balance (controlled by the sympathetic nervous system). 2. State of deletion of fat stores (adipose specific).
- During re-feeding, metabolism is quickly restored in the first control system as energy intake increases but thermogensis (metabolic suppression) continues in the second control system meaning weight gain is redirected as fat to restore adipose tissue levels.
- Some researchers have suggested there may be an aminostatic component to appetite regulation and regulating lean body mass so supplementing with amino acids may increase the rate of fat free mass however this is not substantiated by research (this is possibly why following a high protein diet has become popular).
- An alternative explanation is that skeletal muscle acts as an endocrine organ to regulate appetite – an area for future research.
I feel we can use this research in several ways:
- To discourage restrictive dieting, especially amongst healthy weight individuals, and encourage clients to shift their focus to healthy behaviour patterns. By sharing the research findings on the increased risk of obesity and cardiometabolic disorders in those who diet and that one third of dieters regain more weight then they lose, we can help them see that they haven’t failed at dieting, dieting simply doesn’t work.
- Again, by explaining thermogensis and the way it causes the body to gain more fat than it loses, we can take the shame away from clients who have experienced a steady rate of weight gain over years of dieting.
- We can take the fear away from clients who experience extreme levels of hunger and binge episodes as a result of restrictive dieting. This is not because they are greedy of lack willpower, this is simply because their body is trying to get them back to a healthy place.
- By explaining that there are individual differences in whether weight is lost and gained as fat or muscle so there is no point comparing their body to anyone else.
- To support those in recovery from anorexia (or anyone wanting to gain weight) by explaining that gaining fat first is totally normal and natural and that this will balance out over time.
I’d love to know your thoughts! And if you would like to read the full paper, please drop me an email.
*Kärkkäinen, U., Mustelin, L., Raevuori, A., Kaprio, J., & Keski-Rahkonen, A. (2018). Successful weight maintainers among young adults—A ten-year prospective population study. Eating behaviors.