My exercise physiology professor lectured that if children gain large amounts of fat as they are growing, the body will create more fat cells to store the excess fat. Once created, these fat cells cannot be removed except by surgery. To lose weight, the fat cell size must shrink. Fat cells like to be a certain diameter. Thus, it is very difficult for these people to sustain weight loss. However, many of my colleagues don't recall a similar lecture, and I cannot find information supporting or refuting this. Is what I learned correct? Does this happen only to children or do adult bodies also increase the number rather than size of fat cells for storage? Can you refer me to research on the subject?
Most non-obese young adults have around 30 to 50 billion fat cells. This number increases to 75 billion in full-grown obese people. After maturity has been reached, there is normally very little change in fat cell number when a person maintains a healthy weight. But if a person becomes grossly obese, the number of fat cells can increase, regardless of age. When all existing fat cells are filled to capacity, the body starts producing more cells to provide additional storage. And the production of fat cells can be tremendous, depending on the weight gain.
Fat cells are very influential in weight control because they are permanent. Fat cells do not vanish when we lose weight. Instead, the fat cells shrink. The more fat cells we have, the more storage area we have for fat, which makes it easier to gain weight. Children who are obese are more likely to be obese as adults. Many researchers believe that the fat cells we gain as children stay with us as adults. Obese children may have five times more fat cells than children of normal weight. Dieting in adulthood will decrease the fat cell size but not the actual number of fat cells.
Here are some references on this subject:
- Bjorntorp P, Sjostrom L. 1971 Number and size of adipose tissue fat cells in relation to metabolism in human obesity. Metabolism. 20:703–713
- Bjorntorp P 1974. Size, number and function of adipose tissue cells in human obesity. Horm Metab Res.;Suppl 4:77-83. Review.
- Sjostrom L. 1972. Adult human adipose tissue cellularity and metabolism with special reference to obesity and fatty acid synthesis de novo. Acta Med Scand Suppl. 544: 1-52.
- Hager A. 1977. Adipose cell size and number in relation to obesity. Postgrad Med J. 53: Suppl 2: 101-110.
- Bjorntorp P., Grimby G., Sanne H., Sjostrom L, Tibblin G and Wilhelmsen L. 1972. Adipose tissue fat cell size in relation to metabolism in weight-stabile, physically active men. Horm Metab. Res. 4(3):182-186.
- Faulhaber JD. 1974. Size, number and function of adipose tissue cells in human obesity. Introduction to discussion. Horm Metab Res. Suppl 4: 83-88.