The final, and most effective, way to lower your metabolic thermostat’s set point is through bariatric surgery. For decades, we believed that bariatric surgery worked by preventing you from eating large portions (we refer to this as restriction) while blocking your intestines from absorbing calories (malabsorption). However, as the science of bariatric surgery grows, we are beginning to recognize that the primary way that these surgeries work is by adjusting the hormonal relationship between your brain and your gut to trigger a lowering of your set point. While restriction and malabsorption do play a role early after the surgery, the dominant effects over the long run are the metabolic, set point lowering changes.
Examining the figure below demonstrates how bariatric surgery can trigger patients to lose their hunger and shed weight easily for an entire year after the surgery. Bariatric surgery causes an immediate and significant lowering of your set point- almost overnight. Within days of your surgery, your metabolic thermostat’s setting will drop to your future postoperative weight, leaving a huge discrepancy between your current body weight and the weight your brain believes you to be. This leaves your metabolism well on the “overfed” side which causes your brain, gut, and fat stores to look at your current level of fat stores as excessive. Thus, your hunger is decreased and your metabolism is increased.
I see the effects of this favorable metabolic state every day in my office. First, I see patients fail to experience significant hunger for 1-2 years after surgery. Most patient’s hunger only returns after their actual body weight reaches their new, lower metabolic thermostat’s setting. Second, I see the subtle signs of an increased metabolism in their every movement. Remember that an increased metabolism is primarily driven through an increase in your subconscious drive for movement. Patients develop a gait that I refer to as a “gastric bypass swagger” in which their arm, hip and leg movements become exaggerated in their body’s effort to burn as many calories as possible with each stride.
If you examine the life of a patient after bariatric surgery closely, the impact of the metabolic effects of the surgery become clear. If the primary mechanism of weight loss was through restriction, patients would begin to regain weight once they started eating normal size portions again (1-2 years after surgery). But this does not occur after surgery unless the postoperative patient resumes a diet of calorie dense junk foods- or even worse- sugar sweetened beverages. If the primary mechanism of weight loss was through malabsorption, we would see patients reporting diarrhea after surgery and an examination of their stool would demonstrate undigested food. But patients don’t develop diarrhea after surgery unless they make poor food choices that are either greasy or excessively sugary.
It is only by examining weight loss after bariatric surgery as the result of an immediate lowering of your set point that we can begin to understand what life after surgery is really like. When we view weight loss surgery over the long term, the hormonal impact of the surgery is the dominant effect that we must work to maintain. There is so much myth and lore surrounding weight loss surgery that is driven by our poor understanding of how these surgeries actually work. Because we have attributed weight loss after surgery to restriction and malabsorption, we have encouraged patients to “eat your protein first” to ensure that they stay well nourished in an attempt to overcome their body’s impaired ability to absorb calories. But, ten years after gastric bypass surgery, the predominant problem is weight regain- not starvation. We’ve also encouraged patients to “avoid eating and drinking at the same time” and “avoid carbonation” for fear of stretching out their pouch and destroying the restrictive effects of the surgery. However, we see portion sizes increase in nearly all postoperative patients a few years after surgery. Yet most do not regain a significant amount of weight.
Now that we are looking at bariatric surgery as a set point lowering surgery, not a restrictive and malabsorptive one, the rules for success after surgery change dramatically. Part Two of this book will re-examine the approach to life as a bariatric surgery patient taking our improved understanding of the hormonal influences of the surgery into consideration.