A complex system of endocrinal, neural and chemical mechanism is involved in maintaining a normal body weight. When something goes wrong with this mechanism, and upsets the balancing of energy expenditure with energy intake it causes weight fluctuations. Obesity is one of the results.
The normal non-obese adult has approximately 25 billion fat cells in his/her body. Each fat cell holds 0.5 to 0.6 microgram of lipid. These fat cells develop and multiply greatly during the phases of growth spurt, namely as fetus and during infancy and adolescence.
The obesity gene
During these periods or sometimes at any period of time later in life, hyperphagia or overeating leads to hypertrophy (increase in size of cells) until a maximum of 1 microgram is reached. Thereafter continued hyperphagia leads to hyperplasia or formation of new number of cells. The person or child now has more than normal number of cells. Such a child when he grows up to be an adult finds it extremely difficult to not overeat as the increased fat cells demand to be fed.
The number of cells once increased cannot be reduced. When a person is more than 75% of his desirable weight (BMI > 35) it may be clinically presumed that he has hypercellular obesity.
He will battle with obesity all his life. He will also find himself regaining lost weight faster than others. A chubby child may be cute to look at but it is injustice to the child from a health aspect. There is increased appetite during the adolescence. If this hunger is not managed properly with good eating habits, it can be a cause for obesity. The same is true during gestational period. The increased hunger of the pregnant mother leads to overeating and wrong choices of foods causing gestational obesity. It is a myth that the pregnant woman has to eat for two! She needs only approximately 300 kcal extra. As we age, our body's food requirement is reduced. Our physical activity is also much diminished. But if we continue to eat like an adolescent without making changes in our dietary habits, we put on weight. Once we cross the age of 30, we need 10% lesser calories for every decade thereafter.
Some people are genetically predisposed to accumulation of fat tissue leading to obesity. The regional distribution of fat maybe classified simply as whole body mass, android, and gynoid.
Android obesity or accumulation of fat around the abdomen is risk for diabetes and cardiovascular diseases than other types of obesity.
Gynoid obesity is when fat accumulates mainly in the hip and thigh regions. This is mostly seen in women. There are several methods of assessing body mass. An easy method is the waist to hip ratio where for women this ratio should not exceed 0.8 and for men 0.95
