The two most common obstacles individuals face when attempting to reach their fitness goals are genetics and lifestyle choices. The set-point theory demonstrates how genetics and lifestyle overlap or may actually be the same.
A person's set point is the approximate weight and fat percentage that an individuals body settles into during adulthood. Body fat is regulated in the brain by a mechanism in the hypothalamus. This mechanism chooses the amount of body fat it considers ideal for the body's needs and works to maintain that level. Theoretically, each person has a set point range. A low and a high side, determined by genetics. Where an individual ends up in that range is a result of lifestyle. If a person is active and eats right, they will end up on the lower side of the range.
The regulating mechanism controls body weight in two ways. First, it has an effect on the amount of food you eat. It is responsible for increasing or decreasing appetite to maintain the set point weight. Second, the regulating mechanism can trigger the body's systems to "waste" excess energy if you overheat or conserve energy if you don't eat enough. Energy conservation may lead to muscle loss and a slowing of the endocrine system due to the body's attempt to protect fat stores for future use. In addition, less muscle mass means the body requires fewer calories to function.
An individuals set point is genetically determined. Some people are satisfied with it, others struggle with it all their lives. There are some who can eat every sweet treat that crosses their path and still maintain a low body fat percentage. However, many still struggle with their set point and constantly diet and exercise to lose weight. The truth is, this weight loss is often a loss of both muscle and fat. Once they stop dieting, those who battle fat loss incorrectly or are unable to make the necessary lifestyle changes will ultimately return to their original body composition and most likely gain additional body fat.
On a typical calorie restrictive diet, the body loses lean body mass and in turn, burns fewer calories. As a result, the dieter is severely limited in the amount of food they can eat without experiencing an increase in weight and fat. To complicate matters even more, because fat is burned in muscle tissue, the decrease in lean body mass results in a decrease in the amount of fat burned while either resting or exercising. Poor genetics, in regard to body fat, can be exacerbated by improper dieting and exercise techniques.
Genetics may also play a role in how fast an individual is able to lose body fat. Two people with similar body composition and fat loss (or muscle gain) goals could workout using the same program and the dieter with the "good" genes may reach their goal in less time and with less effort. Genetic predisposition may have a twofold effect on a persons ability to lose weight and fat. It may determine the amount of body fat the system will attempt to store and the speed at which the individual is able to lose body fat.
While there is no way to change a persons genetical predisposition, it is possible to control whether genes are allowed to fully express themselves. If the cause of a persons body fat is genetic, they do not have to be a prisoner to heredity, because you can control what you eat and how much you move. Regular exercise and proper food intake must become "ingrained" in the brain.
The set point theory is applicable to those individuals who workout and eat right. It's for those women who strive to fit into a size 4 pair of jeans or patiently wait for the scale to show them the "ideal" number. It's for the men who focus on six pack abs and 21 inch biceps. It's for everyone who feels like they should all be the same size and shape as everyone else. It is not an excuse for the overweight or obese. The set point theory doesn't not mean that an individual is destined to be unhealthy.