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Why the bigger you are, the HARDER it is to lose weight
Fat cells produce the protein sLR11 which inhibits thermogenesis
This is a process by which fat cells burn calories for energy
The more fat a person has, the more protein will be produced and the less calories burned, preventing weight loss
Experts: Finding could help treat conditions such as obesity and diabetes
For those with a lot of weight to lose, a new study makes for depressing reading.
The fatter a person is, the harder it is for them to lose weight, scientists have discovered.
Heavier people produce more of a protein that inhibits the body's ability to burn fat, researchers found.
This is because fat produces a protein, called sLR11, which stops the process by which cells burn energy to keep warm - and therefore preventing weight loss.
The findings may have implications for the treatment of obesity and other metabolic diseases.
The fatter a person is, the harder it is for them to lose weight, a study has found. Heavier people produce more of a protein that inhibits our ability to burn fat, researchers found
Professor Antoni Vidal-Puig, of the University of Cambridge, who led the team, told MailOnline: 'We identified a protein that prevents the capacity of the individual to make heat.
'If you can’t burn energy to make heat, expending energy, this is going to stop you losing weight.
'This increases in people who are obese. The more fat you have, the more of this protein you produce, and the less likely it is you will lose weight.
'This is because the body cannot burn energy unregulated.
'Like in a car, there needs to be an accelerator and there needs to be a brake.
'As a person gains fat the body has defended itself against losing fat.'
In the body, there are different types of fat cells.
When we overeat, the extra calories is stored in 'bad' white fat cells usually found in the form of love handles and big bellies.
But the body also has another type of 'good' brown fat, which is found in teaspoon amounts on the neck and back in adults.
This type of fat actually burns calories to keep the body warm, in a process known as thermogenesis.
British and Japanese researchers found that the protein, sLR11 - which they believe is produced by fat cells - acts to suppress thermogenesis.
WHY BEING FATTER MAKES IT HARDER TO LOSE WEIGHT
The fatter a person is, the harder it is for them to lose weight, the study found.
Japanese and British researchers discovered fat cells produce a protein called sLR11.
This protein binds to specific receptors on fat cells – in the same way that a key fits into a lock – to inhibit their ability to activate thermogenesis.
Thermogenesis is the process by which fat cells in the body burn energy to produce heat.
Therefore, the more fat a person has on them, the more sLR11 will be produced.
This means thermogenesis will be inhibited and the rate at which the body burns calories to generate heat will be lower, preventing weight loss.
Source: University of Cambridge and Toho University
To come to their conclusions, they wanted to investigate why mice that lacked the gene for the production of sLR11 were far more resistant to gaining weight.
Normally, when mice - and humans - switch from a lower calorie diet to a higher calorie diet, their metabolism increases.
But mice lacking the gene to produce sLR11 responded with a much greater increase, meaning they were able to burn calories faster.
In these mice, genes normally associated with 'good' calorie-burning brown fat tissue were more active in 'bad' white fat tissue, which normally stores fat for energy.
The researchers found that sLR11 binds to specific receptors on fat cells – in the same way that a key fits into a lock – to inhibit their ability to activate thermogenesis.
They discovered the protein acts as a signal in the body.
As people gain more fat cells, more sLR11 is produced so that the metabolism doesn't continue to increase, preventing unrestricted thermogenesis which would waste calories.
When the researchers examined levels of sLR11 in humans, they found that levels of the protein circulating in the blood correlated with the total fat on the body.
In addition, when obese patients underwent weight loss surgery, the amount of fat they lost after the operation was directly proportional to the reduction in their sLR11 levels, suggesting that sLR11 is produced by fat cells.
There is now growing interest in targeting thermogenesis with drugs in order to treat obesity, diabetes and conditions such as heart disease which are associated with being overweight.
The finding could be used to develop treatments for obesity, diabetes and conditions like heart disease that are associated with being overweight, researchers said (file photo)
This is because it offers a mechanism for disposing of excess fat in a relatively safe manner.
A number of molecules have already been identified that can increase thermogenesis and the number of fat cells capable of thermogenesis.
However to date there have been very few molecules identified that can decrease thermogenesis - which the reserachers discovered sLR11 is able to do.
Researcher Dr Andrew Whittle, of the University of Cambridge 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.'
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 Dr Andrew Whittle, of the University of Cambridge
Professor Toni Vidal-Puig told MailOnline: 'There are situations where you don’t want to expand energy, like anorexia, or cancer.
'It might be important to keep energy.
'This protein could be used to help people with these conditions.'
Jeremy Pearson, associate medical director at the British Heart Foundation (BHF), which helped fund the research, said: 'This research could stimulate the development of new drugs that either help reduce obesity, by blocking the action of this protein, or control weight loss by mimicking its action.
'Based on this promising discovery, we look forward to the Cambridge team's future findings.
'But an effective medicine to treat obesity, which safely manages weight loss is still some way off.
'In the meantime people can find advice on healthy ways to lose weight and boost their heart healthy on the BHF website – bhf.org.uk.'
The research was published in the journal Nature Communication.
Source: Daily Mail