“Obesity is a hormonal imbalance, not a calorie one,” is probably a quote from an online post by Jason Fung, MD. I scribbled it down on a Post It©. I’ve written about this imbalance – specifically the way that an elevated blood insulin level blocks fat breakdown (lipolysis) and results in fat build-up (de novo lipogenesis) – many times, most recently in Retrospective #339 and #328. To my constant readers, it must seem like a tired refrain, but to everyone else – basically the entire rest of the world – it’s new information, so it bears repeating.
How is this relevant to those of us who are overweight or obese? We became that way not because we were gluttons, but because we were hungry. We might even have overeaten (with all its attendant guilt), or eaten over frequently, because our bodies told us to – that we needed food to maintain energy balance (homeostasis). We took that “energy in” by mouth (from “food”) because our hormone insulin level was elevated and prevented our bodies from gaining access to our internal source of stored energy: the food stores (fat) that it put away for that purpose.
An elevated insulin level blocks body fat breakdown because our brain gets the message (via other hormones) that we don’t need to use stored energy; we have energy (glucose from carbs) flowing in our blood (with the transporter hormone insulin) from food by mouth, digested and circulating in our blood but not yet taken up by your cells. This other role of insulin is especially relevant for people beginning to get insulin resistance, the hallmark of a pre-diabetic. It is even more relevant for a diagnosed Type 2, who is by definition Insulin Resistant. Insulin resistance is where the pancreas makes more insulin to help push glucose into cells…and the insulin level stays high a long time.
So, what are the implications of this for someone who is maybe heavier than he or she wants to be? To draw from Jason Fung again, “Fasting is about reducing insulin.” With a reduced level of insulin circulating in your blood, your body can now switch naturally to burning body fat for energy. Your body now has access to your energy stores, and since it is being fed by them, you will not be hungry. Your body will be in energy balance. And it will remain in balance so long as you refrain from eating, (fast), or eat Very Low Carb, and you have body fat to burn. As Jason Fung says, “If you don’t eat, you’ll lose weight, guaranteed!” Pithy, huh? Jason Fung has a way with words. I’m not sure where I found these other scribbles, but it was probably also in his blog, “Intensive Dietary Management,” or in Jason Fung’s very good book, “The Obesity Code” (2016).
Then, there’s another important ramification of running on body fat, via fat-burning mode made possible by a lowered blood insulin level: Your metabolism doesn’t slow down. Why is this important? Because if your body (at the cellular level) senses that you have restricted “energy in”, either by eating less (by mouth) while blocking access to stored energy, it will adapt to this calorie restriction by reducing your energy expenditures. Your metabolism will slow down. I’m not sure where I first read about this important point, but I think it preceded Jason Fung! He does makes the analogy, though, of a household budget. If you have less to spend, the rational thing to do is to spend less. The body is a rational mechanism.
The scientific insight into this physiological phenomenon has been around for a while and is widely accepted by medical researchers. It is also widely understood by dieters. People who restrict their food intake by mouth, and eat a balanced diet, by so doing restrict their access to body fat stores. As a result, they are always hungry because there IS an energy deficit. They ARE literally starving themselves. And the body slows down to compensate. Then, when given the opportunity, it engorges itself and restores its natural metabolic rate, and you regain the weight.Conversely, when you are fasting, or you eat Very Low Carb, your blood insulin level lowers and your body has full access to and feeds on its fat stores. Thus, the body’s energy level remains high. Your metabolic rate is constant and you have full energy. You’re not hungry, because your body is being fed. It’s a nice place to be.