Does it seem like no matter how much you exercise and diet, you just can’t keep that weight from coming back? Well, it may not be your fault!

New research shows that your body may be holding on to a steady number of fat cells every year. A study published in Nature found that the human body continually maintains about 90% of its fat cells, with about 10% being replaced annually. The amount of fat cells is actually set at the end of adolescence. And after that, it will never change.

Basically, this means that no matter how much weight you gain or lose, the only thing changing will be the amount of fat inside the cells, NOT the cells themselves. This may explain why overweight men and women find it difficult to keep that lost weight off for good!

Exploring New Treatments for Obesity

Previously, genetic and lifestyle factors were thought to be the only factors contributing to obesity. But these new findings may help researchers better understand how the body controls the turnover of its fat cells. And that, in turn, may lead to new treatments for obesity. “Your body regulates that number of fat cells fairly constantly throughout adulthood,” said researcher Bruce Buchholz. “There’s some pathway that’s controlling this, which could be a target for therapies for obesity.”

Buchholz and his team isolated the DNA of fat cells taken from obese and lean people who underwent liposuction or abdominal wall reconstruction. This enabled them to identify the age of the subjects’ fat cells. “If you’re obese during childhood, it’s very difficult to get thinner,” Buchholz said. “Once you have the fat cells, your body has the capacity of retaining extra fat.”

Lean and obese adults retain the same yearly proportion of cells. But obese people may replace a higher number of cells. Therefore, the difference in total number of fat cells is thought to be set before adulthood. Researchers found that even drastic weight loss – such as bariatric surgery – had no effect on the total number of fat cells. Additionally, studies show that over 75% of obese children go on to be obese adults, whereas only 10% of children of normal weight become obese adults.