Shedding lockdown weight is high on the priority list for millions of Britons as the country prepares to celebrate freedom after restrictions are scheduled to lift in June.
But a new study has found stomach blubber is the hardest of all forms of body fat to lose if adopting the popular diet technique intermittent fasting.
Scientists discovered belly fat is the most resistant due to a ‘preservation mode’ which allows it to stay put while fat around the rest of the body is burned for fuel.
The researchers do not suggest a way to counter belly fat’s preservation mode but say other diets, not intermittent fasting, may be more successful, such as calorie restriction.
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Intermittent fasting involves cycling between periods of fasting and eating and there are a few different methods of doing this.
It is not a diet in as much as it limits how much you can eat, but when food can be eaten.
You may have heard of the 5:2 diet, this is both based on intermittent fasting principles.
This states that for five days of normal consumption, there must be two days of highly restrictive intake.
On these fasting days, only a modicum of calories are allowed, mainly driven by black tea, black coffee and water.
This fasting allows the body to use stored energy by burning excess body fat resulting in weight loss.
University of Sydney researchers analysed more than 8,500 proteins found in body fat deposits of mice.
Any changes to these proteins throughout and after fasting were recorded.
Visceral fat is the technical name for the fat in the abdomen which wraps around internal organs and is designed to protect them.
However, excessive calories can see it protrude, creating an unwanted gut.
This type of fat, the study found, has a cellular mechanism which prevents intermittent fasting from being able to break down the fat.
‘While most people would think that all fat tissue is the same, in fact, the location makes a big difference,’ said senior author Dr Mark Larance from the University of Sydney.
The method of intermittent fasting — cycles of eating normally and bouts of no intake — sees the body’s fat reserves provide energy by breaking down into fatty acid molecules which replace food as the main fuel source.
But analysis of belly fat reveals it does not undergo this transition as readily as fat located elsewhere in the body.
‘This suggests the visceral fat can adapt to repeated fasting bouts and protect its energy store,’ Dr Larance said.
‘This type of adaptation may be the reason why visceral fat can be resistant to weight loss after long periods of dieting.’
The research was done on mice, with the diets of lab animals controlled and scrutinised via mass spectrometry.
Dr Larance added: ‘Mouse physiology is similar to humans, but their metabolism is much faster, allowing us to observe changes more rapidly than in human trials, and examine tissues difficult to sample in humans.
‘This sort of research has been enabled by these new instruments that allow us to ‘look beyond the streetlight’ – it’s hypothesis generating; we knew we would find something but we didn’t know what.’
‘Now that we’ve shown ‘belly fat’ in mice is resistant to this diet, the big question will be to answer why, and how do we best tackle it?’
The research was published in the journal Cell Reports.