The goal of many people in general is to lose weight. In this era of size zero, most people are not satisfied with their current weight and want to lose more weight. Here is a study pertaining to weight loss after dieting and how exercise helps in achieving it.
Exercise may avert weight regain post dieting by decreasing appetite and by burning fat before burning carbohydrates. This is as per a new study conducted at the University of Colorado on rats. Burning fat first and storing carbohydrates for later use in the day may slow weight regain and may decrease overeating by signaling a feeling of fullness to the brain. The study also discovered that exercise may avert the increase in the number of fat cells that could arise during weight regain, challenging the conventional wisdom that the number of fat cells is set and apparently cannot be altered by dietary or lifestyle changes.
These synchronized physiological changes in the brain and the body lower the ‘defended’ weight, which is the weight that our physiology motivates us to achieve, and propose that the effects of exercise on these physiological processes may make it easier to stay on a diet.
The study is known as ‘Regular exercise attenuates the metabolic drive to regain weight after long term weight loss’ and was conducted by Paul S. MacLean and his colleagues.
Weight gain appears to be very simple when the calories consumed exceed the calories expended. But actually the process is quite complex. The laboratory animals could eat as per physiological changes that may suppress appetite or produce the craving to eat. These signals are comparatively weaker in humans, as their consumption may largely be influenced by psychological, cognitive and lifestyle factors. Post dieting, however, the physiological signals appear to play a more significant role in controlling intake. Being constantly hungry after losing weight with a limited diet may play a big part in the weight regain problem. Most of the people are not able to disregard this physiological cue and may be pushed by their biology to overeat and regain the weight they worked so hard to lose.
Some people who are successful in keeping their weight under check apparently share a lot of common characteristics including regular exercise. This was tracked by The National Weight Control Registry. The objective of this investigation was to supposedly expose how exercise affects the body’s physiology to reduce weight regain.
In the study, obesity-prone rats were used. The rats consumed a high-fat diet, as much as they wanted and remained inactive. This was for the first 16 weeks. After this, they were placed on a diet. For the next 2 weeks, they were on a low-fat and low-calorie diet and apparently roughly lost around 14% of their body weight. For eight more weeks, the rats dieted and maintained the weight loss. During this period, half of the rats regularly exercised on the treadmill whereas the other half remained sedentary.
During the relapse phase of the studies, in the final 8 weeks, the rats stopped dieting and consumed as much low-fat food as they wanted. The rats in the sedentary group remained sedentary and the rats in the exercise group continued to exercise.
Contrary to the sedentary rats, the exercisers supposedly regained less weight through the relapse period. They apparently developed a lower ‘defended’ body weight. More fats were burned during the day and the carbohydrates later in the day. During relapse, only few fat cells were accumulated and they supposedly had less abdominal fat. Their drive to overeat may have been reduced. The capability to balance energy intake may have been enhanced with the energy expended.
The sedentary group preferentially burned carbohydrates while sending fat from the diet to fat tissue, during feeding. This preferential fuel use may store more calories as it needs less energy to store fat than to store carbohydrates. Adding to it, burning away the body’s carbohydrates could have a say in the unrelenting feeling of hunger and huge appetite of the sedentary animals.
Exercise may blunt this fuel preference, supporting the burning of fat for energy needs and saving ingested carbohydrates so that they may be used later in the day. The exercise may lead to a much lower appetite and fewer calories ending up in fat tissue when taken together.
Exercise may avert the rise in the number of fat cells which were observed with weight regain in sedentary rats, as per the experts. A population of extremely minute, most probably new, fat cells apparently emerge early in the relapse process in the sedentary rats. Small, new fat cells would not only speed up the process of regain, but may also enlarge the fat storage capacity in the abdomen. It may also enlighten as to why sedentary rats exceed their preceding weight when they relapse.
The number of fat cells is apparently determined by genetics rather than being controlled by diet or lifestyle. As this effect of exercise is a new finding, the team will conduct an additional study to show that exercise may avert the formation of new fat cells early in relapse and not merely changing the size of pre-existing fat cells.
This study was published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology.