Doctors advise patients to lose weight and maintain a healthy weight for their body type in order to reduce the risk of heart attacks, osteoarthritis, and some cancers; lower blood pressure; and improve mental health. Unfortunately, this is often easier said than done. Here’s why.
In order to undergo significant weight loss, we need to establish a new balance between the calories we consume and the energy we spend burning these calories. A part of our brain, called the hypothalamus, regulates this balance by sending hormones through our body to regulate our hunger levels and controlling our metabolism – how quickly we expend the caloric energy we consume.
The hypothalamus helps our body find a “weight set-point” and adjusts our metabolism and hunger levels to best maintain this point. This bodily function is precisely why moderate weight loss can be difficult to achieve; the body is resisting this weight loss because it wants to maintain the equilibrium of the “weight set-point.”
Your brain then sets into motion a number of responses across your body aimed at putting the weight back on.
One of these responses is to signal to muscle tissues that they should become more efficient, meaning they burn fewer calories. As a result, you need fewer calories to get through your day than would be expected based on your weight alone. For example, a person who weighed 200 lbs. (91 kilograms), and then lost 20 lbs. (9.1 kg), would require about 300 to 400 fewer calories per day than a person who weighed 180 lbs. (82 kg) without dieting, in order to maintain that weight, said Dr. Michael Rosenbaum, a professor of pediatrics and medicine at Columbia University Medical Center who has studied weight-loss maintenance.
Another change is that areas of the brain involved in the rewarding feeling you get from eating food become more active, and areas of the brain involved in restraining eating become less active, Rosenbaum said. This translates to increased appetite and overconsumption of food compared to the calories you need.
With these responses, “you’ve created the best possible scenario to re-gain the weight you’ve lost,” Rosenbaum said. [The Best Way to Keep Weight Off]
In other words, your body essentially defends its fat stores, making it much harder to keep weight off, especially in an environment where food is plentiful.
For people who are obese and lose significant weight, the body continues to adhere to their bodies’ original “weight set-point.” People who are obese generally have higher resting metabolic rates (the rate at which the body burns calories while in rest). After losing weight, however, the body’s resting metabolic rate drops dramatically and the hypothalamus sends more hunger signals through the body – both of which will cause weight gain.
This is ultimately what happened to the contestants of the show The Biggest Loser. Although each of these contestants lost significant percentages of their body weight on the show, almost all of them struggled to maintain their new weight in the six years following the show.
What doctors now advise for individuals striving to lose weight, and maintain this weight loss, is to perform strength exercises that preserve muscle mass and help raise the body’s resting metabolic rate. This should be, however, combined with consistent exercise and a permanent decrease in calorie consumption.
As with any other physical development, weight loss is a process that should be maintained long term, not accomplished within the matter of a few months.