A new research has come up with an explanation as to why some find it harder to lose weight, suggesting that the fatter we are, the more our body appears to produce a protein that inhibits our ability to burn fat.
The findings may have implications for the treatment of obesity and other metabolic diseases.
Most of the fat cells in the body act to store excess energy and release it when needed but some types of fat cells, known as brown adipocytes, function primarily for a process known as thermogenesis, which generates heat to keep us warm. But the researchers from the Wellcome Trust-Medical Research Council Institute of Metabolic Sciences at the University of Cambridge, UK, and Toho University, Japan, have shown that a protein found in the body, known as sLR11, acts to suppress this process.
Researchers investigated why mice that lacked the gene for the production of this protein were far more resistant to weight gain. All mice - and, in fact, humans - increase their metabolic rate slightly when switched from a lower calorie diet to a higher calorie diet, but mice lacking the gene responded with a much greater increase, meaning that they were able to burn calories faster.
The authors suggest that sLR11 helps fat cells resist burning too much fat during 'spikes' in other metabolic signals following large meals or short term drops in temperature. This in turn makes adipose tissue more effective at storing energy over long periods of time.
Andrew Whittle, joint first author, said: "Our discovery may help explain why overweight individuals find it incredibly hard to lose weight. Their stored fat is actively fighting against their efforts to burn it off at the molecular level."
The study is published in the journal Nature Communication.