The Times

Tom Whipple Science Editor

Gerry Gajadharsingh writes:

“More research backing up the idea that intermittent fasting is actually good for you. The great thing is that you don’t have to be as extreme as the protocol suggests (only eating for 12 hours in 48). The team at Metabolic Balance worked out over 15 years ago that leaving 5 hours in between meals, minimises the insulin response. Insulin is released in response to eating carbs and is proinflammatory. The western habit that has developed over the past 30 years is one of snacking. Simply getting people to eat during their main meals, breakfast, lunch or dinner and to NOT snack can also derive the health improvements suggested below. The other interesting thing is that the average weight loss on a Metabolic Balance programme is between 2-4kg in the first 2 weeks (assuming you have been given a weight loss programme).

 Almost all people look at me in that strange unbelieving way, when I discuss not eating between meals, as if it is simply not possible. I have yet to come across a person, who is being supervised on a proper Metabolic Balance programme, who is still hungry after 2 weeks. It’s not all about weight reduction, it’s about changing your metabolism.”

Fasting every other day leads to weight loss, lower cholesterol and a healthier heart, according to the largest study of its kind.

After four weeks in which they could only eat for 12 hours in every 48, researchers found that 30 healthy people had on average lost 3.5kg, eaten 35 per cent fewer calories, and had less belly fat. The scientists spotted no obvious concerning side-effects, even after observing a separate group that continued the practice for six months.

They cautioned that the study could not say whether fasting is sensible for longer periods, and that anyone considering it even for a short time should consult a doctor.

There is growing evidence for the health benefits of fasting, famously popularised in the 5:2 diet. One of the reasons scientists are excited by it is that the effects of abstaining from eating appear to extend beyond mere weight loss. “There’s been data and research from flies to worms to rodents showing this fasting is needed for regeneration,” Harald Sourij, from the University of Graz in Austria, and an author of the research, said.

His latest research is the largest study to investigate the health effects of fasting every other day in humans in a controlled experiment. He and his colleagues took 60 people of a healthy weight and split them into two groups. One half could eat normally, the other ate nothing for 36 hours then could feast unrestricted for 12.

The study, published in the journal Cell Metabolism, found that although people attempted to compensate for their hunger on the feasting day, they never entirely made up the lost calories. Although none were obese to start with, all seemed to benefit from the weight loss, and there were also signs that their rate of ageing had slowed.

“What we found is it improved cardiovascular risk factors,” Professor Sourij said. “There was a reduction in blood pressure, in inflammatory markers . . . all these things that are shown in animal data to be associated with longevity.” More than that, it seemed to be safe. “We looked at bone health, the immune system and red blood cells. There was no sign of any adverse events or deficiency.”

One theory about why fasting may be effective is that it is what humans evolved to do. “We developed in a place where there was not always excessive food available,” Professor Sourij said. “Then, our lives always had a time of fasting and a time of feasting.”

Despite the positive findings, Frank Madeo, a co-author of the paper and professor at the University of Graz, said that people should be wary of routine fasting. “We feel that it is a good regime for some months for obese people to cut weight,” he said. “However, further research is needed before it can be applied in daily practice.

“Additionally, we advise people not to fast if they have a viral infection, because the immune system probably requires immediate energy to fight viruses. Hence, it is important to consult a doctor before any harsh dietary regime is undertaken.”