A new study sheds light on why some people struggle to lose weight.
The study of mice, published in the journal Nature Communication, found that a particular protein called sLR11 (also found in humans) prevents fat cells from releasing energy and therefore our ability to lose weight.
Mice, which lacked the gene to produce this protein, struggled to gain weight and tended to burn fat at a much faster rate.
When the researchers from the University of Cambridge analysed the levels of sLR11 in people they found that those with more of the protein had a higher total fat mass.
"Our discovery may help explain why overweight individuals find it incredibly hard to lose weight," said co-author, Dr Andrew Whittle. "Their stored fat is actively fighting against their efforts to burn it off at the molecular level."
It is not the first study this year to show what we already know: weight is more complicated than calories in calories out.
One small study by Canadian researchers found that different people respond very differently to the same carolic deficit.
Some participants' metabolism sped up when they were put on a 24-hour fast, while the metabolic rate of others – whom the researchers referred to as "thrifty" – slowed down when they fasted, meaning that the less they ate, the less they burned too.
"Therefore, when restricting calories, the body of a thrifty person slows its metabolism more in an effort to conserve energy, making weight loss more difficult," Susanne Votruba, the paper's lead author, said.
It's further confirmation that, inasmuch as there is an epidemic of people eating too much in general and certainly too much of the wrong thing, there are more pieces to the obesity puzzle.
They are findings that have implications for all of us, says Associate Professor Amanda Salis, from the University of Sydney's Boden Institute of Obesity, Nutrition, Exercise & Eating Disorders.
"This research provides further insight into why it is so difficult to lose weight," she says of the latest study.
"It also reinforces the importance of acting to reverse any weight gains as soon as feasibly possible, to help prevent possible changes in physiology – such as secretion of this sLR11 protein – that can make it harder for you to lose the weight in the longer term."
For this reason, we should not delay dealing with weight gain.
"If you put it off, the window of opportunity for change may close to some extent," Salis says.
"On the upside, the research also suggests that losing weight could induce changes in the body (such as a reduction in secretion of the sLR11 protein) that promote further weight loss and facilitate weight maintenance.
"It's the old adage of 'success breeds success'. This is in keeping with the finding that people who have lost weight and kept it off for two years are significantly less likely to regain weight than people who have kept their weight off for a shorter period of time."
Associate Professor Amanda Salis and her team are seeking people living in the Sydney metropolitan area for clinical weight loss trials. For more information, please e-mail Amanda's team on tempo.diet@sydney.edu.au.
