Overweight people often find it very hard to shed their excess kilos. New research has now identified a protein that blocks the body's ability to burn off fat and discovered that the heavier we are, the more of this protein we produce.
The researchers, from the University of Cambridge in the UK and Toho University in Japan, suggest their discovery may change the way we treat obesity and other metabolic diseases. In contrast to the more abundant white adipocytes, or white fat cells, that store energy, our bodies contain much smaller amounts of brown adipocytes, or brown fat cells, that burn fat to keep us warm - a process known as thermogenesis.
The new research reveals that a protein known as sLR11 appears to suppress thermogenesis in fat tissue. On further investigation, the team discovered that the protein binds to specific receptors on fat cells so as to block their ability to trigger thermogenesis and convert fat to heat.
The team found that mice which were unable to produce the protein were more resistant to weight gain when put on a higher-calorie diet, when compared with mice that did not lack the protein. In humans, the team found higher blood levels of the protein were linked to higher total body fat. Also, when they looked at obese patients undergoing bariatric surgery, they found the amount of weight loss following surgery was in line with falls in sLR11, suggesting the protein is released by fat cells.
The researchers suggest sLR11 plays an energy conserving role to prevent energy wastage in fat tissue, and this role is exaggerated in overweight and obese people, with the result that the higher a person's BMI, the harder their body fights to conserve energy.