Is adaptive thermogenesis the cause of stagnation during weight loss?

 

When browsing fitness-related internet forums, you can often find entries by desperate users who claim that they provide very small amounts of calories (700-1000 kcal per day), devote many hours to exercise and do not notice any progress in reducing body fat, and sometimes even there is regress in them, which seems completely absurd. 

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Student at the Department of Nutrition of the Faculty of Human Nutrition and Consumption Sciences at SGGW. He conducts individual consultations and dietary seminars. He is also the author of several dozen articles on nutrition and physical activity published in magazines, such as Bodybuilding and Fitness Sport for All, Fitness Authority and Muscular Development. 

In order to explain these mysterious observations, it is worth moving back in time. The Second World War was coming to an end. The Allies, liberating subsequent cities from the German occupation, found many starving, emaciated civilians. Therefore, there was a need to expand knowledge about the impact of starvation on the human body, as well as to learn effective ways of restoring health to the hungry. In November 1944, over 400 healthy men responded to the “Will You Starve That They Be Better Fed brochure” expressed willingness to take part in an experiment later called “Minnesota Starvation Experiment 1. Finally, 36 volunteers with the best physical and mental health were selected. 

The methodology and results of the Minnesota Starvation Experiment are presented in detail in a large volume of monographs (1385 pages) of The Biology of Human Starvation published in 1950. For the purposes of this article, we will focus only on selected aspects of this experiment related to adaptive thermogenesis. Participants of the discussed experiment during the first 12 weeks provided a number of calories ensuring the maintenance of body weight (approximately 3200 kcal). In the next stage (24 weeks) their consumption was reduced by about 50% (to the amount of 1500-1600 kcal). The diet in this period was based on foods most often consumed by starving people in occupied Europe (including bread, pasta, potatoes and other vegetables), so it was quite poor with proteins and nutrients. The aim of this stage was to reduce the participants’ weight by 25% of the initial mass. Therefore, the supply of food was dependent on the weekly loss of body weight. The participants were additionally obliged to daily physical exercise (6.5 – 9 km of walk)