Our appetite control system not only regulates our food intake in the short term, but our weight over the long term. It does this by sensing the amount of fat or adipose tissue we have stored. The body weight and amount of fat stores that our body tries to maintain is called our set point. You can think of set point like a thermostat for weight. If our weight drops below the thermostat setting, it compensates by increasing appetite and slowing metabolism until we regain the weight. The same thing happens when we gain weight. We feel fuller and our metabolism speeds up until we lose weight back to our set point. Given that for some people, weight steadily rises, you may be wondering, how can it be that we have a set point? Why do these compensatory responses kick in to help us lose weight? Much research now indicates that in obesity, our bodies are no longer functioning normally. The set point ratchets up, and our body fights hard to defend this new set point. In fact, our set point can steadily increase upwards or slide downward. It is not fixed. Let's look at two scenarios. The first at our set point where body weight is normal. When a person with normal body mass index is placed on a very low calorie diet, he or she will likely lose weight. But once allowed to eat at will, our energy balance system kicks into drive weight back to our starting point. The same happens when we're intentionally overweight. Once allowed to eat at will, we subconsciously lose appetite and our brain speeds our metabolism until we lose weight. In the case of obesity, set point rises in proportion to our body fat. The same defense has tried to maintain the new hire set point. So, even if weight loss is hard-earned by following a diet, it becomes hard to maintain that weight loss. Our body acts like we're starving, even though we may be overweight. While often people who are overweight feel they may lack the discipline to lose weight and keep it off, science is suggesting that obesity is a disease where our control systems become abnormally regulated around a higher set point and the body doesn't function normally. The main takeaway is that even though we focus so much on how our eating and exercise behavior controls how our body functions, the reality is that the way our body functions is what controls our eating behavior. While we view regaining weight and reverting back to being overweight as failure, what is really happening is our body is fighting what it perceives as the threat of starvation due to a higher set point. It's still frustrating, but understanding why this happens can help you understand how to work with your body to successfully lose weight and keep it off. Over the course of the following weeks, one of the things we're going to focus on is how our environment, not just our food, but also our habits can affect our set point to lead to obesity. Targeting these factors will help get to the root cause of obesity so that you can create an individualized plan for managing weight long term.