Losing weight and keeping it off
Growing evidence suggests obesity is a disorder of the body’s intricate energy balance systems.
Once an individual loses weight, the body typically reduces the amount of energy expended at rest, during exercise and daily activities while increasing hunger. This combination of lower energy expenditure and hunger creates a “perfect metabolic storm” of conditions for weight gain.
Your body has a set point that affects your weight. If you’ve been trying to lose and maintain weight but you haven’t had any luck, you are likely fighting against the normal workings of your body. Body weight and fat levels are regulated by a complex system of signals in your body. These signals control your appetite, digestion, energy balance, and metabolism to keep your body weight and fat at a steady level, or “set point”.
Your body’s set point is part of a basic biological instinct. When body weight and fat levels fall below your set point, your body activates defense mechanisms to maintain body weight and fat in order to prevent starvation, even in people with obesity.
Throughout most of human history, calories were scarce and hard to get, so we have numerous natural defenses against starvation.
We have no defenses against overeating because we never needed them before.
Everyone’s set point is different and can be changed (for example with bariatric/metabolic surgery). It appears that the body regulates fat set points similarly to how it regulates other body functions such as blood glucose, cholesterol, and blood pressure. Set points are affected by genetic, developmental, and environmental factors. Changes in any of these factors can lead to an elevated set point for body fat storage. For example, changes in the chemicals and nutrients contained in our foods can affect our brains in ways that increase the amount of food we eat and increase our body fat set point.
Additionally, as you gain weight, your set point is increased and your body works to defend the higher set point. Your body is smart, and it adapts when new things come its way. But, sometimes it’s not for the better. Your body doesn’t realize it’s overweight and it continues to store higher amounts of fat than necessary.
Because your body works to defend its set point, dieting and exercising are rarely effective in helping people with obesity achieve and maintain a healthy weight long-term. When you go on a diet, your body thinks it’s being starved and its survival instincts kick in. As a result, your body stores energy-rich body fat, and you can’t lose weight easily. On average, a 200-pound patient fighting obesity with diet and exercise alone would only be able to achieve a sustained weight loss of 4 pounds over 20 years.
When weight is lost, lower body fat levels trigger hormones that encourage the body to get back to its previous weight set point. While dieters may initially lose weight, their bodies change levels of hormones that encourage weight regain in response to the weight loss. These hormones increase appetite, decrease feelings of fullness, and slow down metabolism. This is a powerful defense mechanism and may explain why the majority of weight loss attempts fail.