|Image 1: Geoffrey Cannon's "Dieting Makes You Fat" was first published in 1983 and has lost nothing of its topicality.|
Dieting makes you fat - fullstop!
From earlier as well as more recent studies on the effects of starvation, calorie restriction and exertional physical training, sleep and energy deprivation during boot camp like activities in the army, we know that prolonged caloric restriction and/or exercise induced energy deficiency will lead to hyperphagia and a subsequent "fat overshoot". As the data in figure 1 goes to show, the latter can be pretty profound and ranges from +2.7kg in the seminal fasting study by Benedict from 1907 up to 6.5kg in the well-powered (n=700) food rationing study, Fleisch et al. conducted after WW2.
|Figure 1: Fat gain (in kg) after fasting, restricted eating and boot-camp like training in an energy deficit (left) and lean mass and fat loss and regain in the Minnesota experiment (data based on summary by Dullo. 1997 and Keys. 1950)|
Did you try to lose weight in puberty? Well that's the reason you are fat, now.
A 1999 study by Stice et al. shows that it does not even take a 12-week period of restriced eating (-50% in the Minnesota experiment) to get caught in the vicious circle of yo-yo dieting. For the 692 female teenagers from the ninth grade of a a Californian high school, even the allegedly harmless "I got to get in shape for spring" diets, were associated with a statistically significant shift in the onset of obesity (Stice. 1999). With anxiously monitoring your caloric intake and being only marginally less detrimental than actual dieting:
- caloric restraint: +192% increased chance of early obesity (p < 0.001),
- dieting (self-labeled): +224% increased chance of early obesity (p < 0.01),
- exercise or weight control: +25% increased chance of early obesity (p < 0.01)
- (ab)use of laxatives / appetite suppressants: +85% risk of early obesity (p < 0.1)
|Figure 2: Basal metabolic rate (BMR) fatty acid and carbohydrate oxidation rate (FOR, COR) before and after weight loss interventions in subjects with and without metabolic syndrome (left); changes in BMR, FOR and COR in male and female study participants (data adapted / calculated based on Soares. 2012)|
- 484kj/day and 414kj/day reduction in the subjects who were either healthy or whose metabolic syndrome did not go into remission vs.
- 670kj/day reduction in the "lucky" ones who got rid of their metabolic syndrome (criteria according to Alberti. 2009)
The diet trap and the myth of reductions in fat-free mass
|Figure 3: Ratio of resting metabolic rate to fat free mass before and 4 and 8 weeks after a protein sparing fast; means, top; individual, bottom (Elliot. 1989)|
So, no matter how you look at it, classic dieting may make slimmer in the short run, but whenever larger caloric deficits and faster weight loss come into play (irrespective of the amount of lean muscle you may lose), caloric restriction and exercising just to lose weight, are going to set you up for a fat rebound!