Neither fat cell death nor its generation rate is altered in early onset obesity, suggesting a tight regulation of the number of fat cells in obese adults.
Fat cells change in size but no one had ever measured fat cell turnover, Buchholz said. An increase in cell size means it can hold more mass.
Obesity is increasing in epidemic proportions in most countries and poses a public health problem by enhancing the risks for cardiovascular diseases and metabolic disorders such as type 2 diabetes. According to the Centers for Disease Control and Prevention, the prevalence of overweight and obesity has increased sharply for both adults and children since the 1970s. Data from two National Health and Nutrition Examination surveys show that among adults aged 20-74 years the prevalence of obesity increased from 15 percent (in the 1976-80 survey) to 32.9 percent (in the 2003-04 survey).
The two surveys also show increases in overweight children and teens. For children aged 2-5 years, the prevalence increased from 5 percent to 13.9 percent; for those aged 6-11 years, prevalence increased from 6.5 percent to 18.8 percent; and for those aged 12-19 years, prevalence increased from 5 percent to 17.4 percent.
In the Nature study, the team first found that there was a direct correlation between the measures of fat mass (measured from body mass index (BMI) and fat cell volume in subcutaneous fat, which represents about 80 percent of all fat, and visceral fat.
In a study of 687 adults, the researchers found that number of fat cells increases in childhood and adolescence, but levels off and remains constant in adulthood. The group looked at whether the number of fat cells changes under extreme conditions such as drastic weight loss by radical reduction in caloric intake, such as through bariatric surgery. The treatment resulted in a significant decrease in BMI and fat cell volume; however, it did not reduce the number
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DOE/Lawrence Livermore National Laboratory