At last years Society for the Study of Ingestive Behavior meeting, the keynote presentation related to perhaps the leading hypothesis of weight gain - reward driven eating behavior. Consider the concept that palatability (the pleasure value of food) may raise the “body fat set point,” which is the level of body fat that your brain tries to maintain through it’s subconscious orchestration of hunger, energy expenditure, temperature, and hormones. Rates of obesity have taken a sharp turn upwards since 1980. We are in the period of engineered food and flavor. Seventeen thousand new food products are introduced per year. Scientists know how to make you really desire foods by making them hyperpalatable (super pleasurable). According to this hypothesis, to which I ascribe (in fact, my PhD thesis relates to a component of this topic), it’s not the carbs, fats, or proteins per se that are the cause of increased body weight (although they are, of course, involved in the process). Rather, it is the intense pleasure stimulation from engineered foods that changes brain receptors such that weight gain goes up unchecked, which is abnormal.
Stephan Guyenet, PhD recently wrote a groundbreaking review article for the Journal of Clinical Endocrinology and Metabolism articulating the problem and potential mechanisms of this hypothesis. Stephan writes:
Obesity occurs in genetically susceptible individuals and involves the biological defense of an elevated body fat mass, which may result in part from interactions between brain reward and homeostatic circuits. Inflammatory signaling, accumulation of lipid metabolites, or other mechanisms that impair hypothalamic neurons may also contribute to the development of obesity and offer a plausible mechanism to explain the biological defense of elevated body fat mass.
There is a great deal more to say about this subject but for now, I will pause and ask that you watch the video. I will close with one more point to help you think about this concept. May people will gain weight by regularly consuming calorie free diet soda and will lose weight when they give it up. By giving up diet soda, these individuals are not directly changing caloric consumption but they are changing flavor stimulation.
If you’re interested in a more thorough scientific discussion on how the brain regulates body fat, please check out my podcast with the Body Rx show, Episode #29 – central energy regulation. I come in at min 12.