This a long one, but for those of you that know Dr. Steve, you know that he does cut corners on answering questions. 😁 ❓Question: Why is starvation and/or severe caloric restriction a concern as a primary method for weight loss amongst many metabolic health programs, and why is it so prevalent and rampant as a form of general nutritional advice? 💚 Answer: This is actually one of the most important questions in all of weight loss medicine, because it forces us to distinguish between how weight can be lost and how physiology is restored. Those are not the same objective. When people hear me say that I do not begin with severe caloric restriction, they sometimes assume I am saying calories do not matter. That is not what I am saying at all. Physics always matters. The First Law of Thermodynamics has not been suspended simply because we are talking about human biology. What I am am saying is that the body decides how easy or difficult it will be to create that energy deficit, and that decision is made primarily through physiology, not mathematics. In other words, calories determine whether weight changes, but physiology largely determines whether a calorie deficit is sustainable, tolerable, and metabolically healthy. This is where I separate what I call front-loading physiology from front-loading mathematics. Most traditional weight-loss programs begin with arithmetic: “Eat 1,200 calories,” “Cut 500 calories per day,” or “You can eat anything, just eat less.” Our approach begins somewhere entirely different. I ask, “What biology can we restore first so that eating less becomes the natural consequence, rather than the daily battle?” Those are two completely different strategies, even though they may eventually arrive at a similar energy intake. The reason severe caloric restriction is such a difficult place to begin is because the body has evolved remarkably sophisticated systems to defend against perceived energy shortage. The hypothalamus (the primary energy-regulating center of the brain) is not counting calories on a phone app. It is integrating thousands of incoming signals every second: gastric stretch (stomach), nutrient availability, circulating glucose, fatty acids, amino acids, leptin, insulin, GLP-1 (glucagon-like peptide-1), PYY (peptide YY), CCK (cholecystokinin), ghrelin, thyroid hormone, sympathetic nervous system activity, and many others.