Anybody who has tried to lose weight knows how difficult it can be. But for many people, the initial weight loss isn’t the hardest part: Keeping it off over time is even more of a challenge.
In an effort to understand why this is so and what might help people maintain their weight loss, researchers have studied this issue from numerous angles. Some research has focused on hormones in the body that influence appetite, some on environmental cues to eat or to refrain from overeating, some on drugs to help with weight loss, and some on the self-reported habits of people who have lost weight and kept it off.
This article takes a look at some of the reasons it can be hard to maintain weight loss and what research has shown that might be of practical help to those who are trying to do just that.
Barriers to weight-loss maintenance
There are many factors working against a person who is trying to maintain weight loss. These hurdles may be metabolic, hormonal, and environmental.
Metabolic hurdles. One of the ironies of weight loss is that the more you lose, the harder you have to work to lose more. This is in part because the body’s metabolism slows down—meaning it burns less energy, or fewer calories—both at rest and during exercise following weight loss. Some studies suggest that the decrease in amount of energy burned may be more pronounced in people who were previously obese than in those who were never obese. However, it is not clear that this increased metabolic slowdown is permanent, nor that it necessarily hinders weight maintenance efforts.
Hormonal influences. Various hormones help regulate hunger and fullness. Leptin, which is made from fat cells, tells the brain when a person is full. At first, obesity researchers thought that leptin might be useful as a treatment for obesity. However, it was found to be effective only in a small percentage of obese people who do not produce their own natural leptin (a rare genetic disorder). Many obese people have naturally high levels of leptin and do not respond to leptin injections by eating less or losing weight. In fact, it is believed that many obese people are “leptin resistant” in much the same way as people with Type 2 diabetes are insulin resistant. Research is ongoing to determine what causes leptin resistance and how it might be treated or circumvented.
Ghrelin, which is released mainly in the stomach, stimulates appetite. Its level rises between meals and falls sharply after eating. Some studies have shown increased ghrelin levels in obese people who have lost weight through dietary changes. It is not clear whether levels eventually return to normal during weight maintenance. In contrast, however, studies have found decreased ghrelin levels in people who have had gastric bypass surgery to treat obesity. Reduced ghrelin levels may contribute to the success of maintaining weight loss after this surgery.
A few small studies have examined whether the proportions of fat, carbohydrate, and protein in a meal influence ghrelin levels after the meal in healthy adults. While all the meals in the studies lowered ghrelin levels somewhat, the higher-protein meals suppressed ghrelin for the longest amount of time.
Getting too few hours of sleep at night can lower leptin levels, raise ghrelin levels, and increase hunger and appetite. Getting enough sleep, therefore, may help to control hunger and appetite and, consequently, weight gain or regain.
Insulin is another hormone of interest to people with diabetes. Produced by the pancreas, insulin helps your body store and use glucose. However, in Type 1 diabetes, the pancreas no longer secretes insulin, and in Type 2 diabetes, insulin production typically declines over the years, and many people with Type 2 diabetes eventually need to supplement the insulin their body makes with injected, infused, or inhaled insulin.