Brown fat, which helps use energy and burn calories, and was previously believed to only to exist in babies, has recently been shown to occur in adults as well. The discovery of the presence of this “good fat” in adults lays foundations for potential obesity and diabetes treatments that stimulate brown fat growth.
Most types of fat, known as white fat, store energy, and account for weight gain. While energy storage is essential, excess calories, often a result of unhealthy diets, lead to excess fat/energy storage, and subsequent obesity. More than 30% of Americans are considered obese, which puts them at increased risk for the rising epidemics of diabetes and heart disease.
A recently published study has shown that an alternative type of fat, called brown fat, is “metabolically active” in adults, a surprising finding, as brown fat was previously thought to only be active in babies. Instead of storing energy, brown fat helps utilize energy and burn calories, making this fat a potentially useful tool for weight loss, and improved glucose metabolism. Says senior author, Dr. C. Robert Kahn, “The fact that there is active brown fat in adult humans means this is now a new and important target for the treatment of obesity and type 2 diabetes.”
The study was performed through an analysis of 1,972 patients who received what’s known as positron emission tomography/computed tomography (PET/CT) scans, which can show fat deposits, among other things. Several general observations were made through analysis of these scans. It was found that younger individuals had a higher occurrence of brown fat, and females more often had larger brown fat deposits than males (specifically, 7.5% of females had “substantial” brown fat deposits, opposed to 3% of males), and the majority of brown fat deposits were found in the neck. Also, brown fat levels were seen to be higher in individuals of normal weight and healthy blood glucose levels, which was to be expected due to brown fat’s calorie burning properties. Brown fat was also seen to be more “metabolically active” in individuals living in cold weather, because the burning of energy naturally generates heat within the body.
Dr. Kahn commented on some of the above observations: “What is of particular interest is that individuals who were overweight or obese as measured by higher Body Mass Index (BMI) were less likely to have substantial amounts of brown fat. Likewise, patients taking beta-blockers and patients who were older were also less likely to have active brown fat. For example, individuals both over age 64 and with high BMI scores were six times less likely to have substantial amounts of brown fat.”
The author’s also believe that the observed incidence of brown fat is an underestimate, due to limitations of PET/CT scans, suggesting even further potential for future brown fat utilization. Says Dr. Kahn, “these numbers clearly represent an underestimate, since PET/CT can only detect collections of brown fat cells of a certain size and activity, and could miss smaller and less active deposits.”
It is the hope of the author’s that the observed, and expected larger abundance, of brown fat in human adults, can be utilized through new therapies that stimulate it’s growth. If this were shown to be possible through further research, new techniques for battling obesity and diabetes could result. Concludes Dr. Kahn, “this study demonstrates that it [brown fat] is both present and appears to be physiologically important in terms of body weight and glucose metabolism. We hope this opens up a new therapeutic area for obesity and type 2 diabetes by modifying the activity of brown fat.”
Source: Defeat Diabetes Foundation: Kahn, C. Robert. Jastive, Kira. New England Journal of Medicine press release. April 2009.