How to Prevent Regaining Your Weight After Dieting
Regain weight after diet is the most common response following a “successful” diet. This is caused by a compensatory slowing of the metabolism and an increase in hunger during the diet that can persist for years after the initial weight loss. The progressive slowing of metabolism occurs no matter how the weight loss was produced–traditional calorie restricted diets, low carb, high or low fat foods, medication, and even gastric bypass. It occurs with or without exercise and in the face of maintaining limited calories after the initial dietary period. A recent report showed that 1/3 or more of the “Biggest Losers” on NNC-TV regained their weight.
What is Successful Weight Loss?
Successful weight loss is keeping at least 10% of the body weight off for at least one year (this definition differs with the FDA, who state that an effective weight loss drug only has to produce a 5% loss. Many researchers find that only 10-20% of overweight individuals are able to obtain the goal of “successful weight loss”. This occurs no matter what diet or exercise plan is employed.
The figure below is adapted from Sumithran, P et al from New England Journal Of Medicine (2011:365:1597-1604). It shows the regain of weight following 10 weeks of diet and weight loss despite eating calories calculated for weight maintenance.
Why Weight is Regained after Weight Loss
The reason why 90% of dieters regain their weight within a year is not the result of a lack of willpower, but the fact that hunger is increased during and after weight loss. These changes continue for several years after, during which time the body tries to regain its lost weight. Studies have shown that this is due to a rise in the levels the hormones and chemicals causing hunger including Grehlin, and gastric inhibitor polypeptide.
The changes in hunger perception during and after weight loss are well-illustrated in the studies of Dr. Sumithran and colleagues in the graph below. They evaluated hunger before and during a weight loss program and during the maintenance phase by providing a standardized meal and measuring the degree of hunger reported by the subjects over the following six hours.
In the graph, the solid black dots illustrate the hunger patterns for four hours after eating a standard meal before the weight loss. Hunger starts off at 32, drops 30 minutes after eating to almost zero, then gradually increases over the next 120 to 240 minutes, ultimately reaching levels experienced before the meal.
Hunger Persists for More than a Year After Weight Loss
For subjects on their 10th week of the diet, the clear boxes show increased hunger before the meal (as would be expected) which persisted for four hours after the meal. The triangles show an increased hunger pattern before and after a meal when the subject returned to “normal eating” a year after the weight loss. These values are similar to the hunger patterns seen during the dietary phase.
This pattern of increased hunger after completing a weight loss program may be one of the reasons for the common difficulty of maintaining weight loss after most diets, as well as the need for continued treatment after the initial weight loss—either surgical or with medication.