How intermittent fasting may raise risk of colon CANCER and the foods you should avoid on the diet

Fasting like Mark Wahlberg could cause cancer, early research suggests.

In a study on mice, researchers found that rodents who fasted for 24-hours before eating had a ‘profound’ risk of pre-cancerous tumors forming in their gut.

This may be because the ‘refeeding’ stage causes cells in the intestines to become overactive, increasing the risk of cancer-causing mutations occurring.

Dr Omer Yilmaz, a biologist at MIT who led the study, cautioned that it was not carried out in humans — so could not be directly compared to people.

But he said the results suggested those trying intermittent fasting should avoid foods like red meat charred steaks, which are being increasingly linked to the colon cancer epidemic in young people.

This graph shows that the mice who fasted for 24-hours and then ate food were most likely to have tumors in their intestines 

Dr Yilmaz said: ‘I want to emphasize that this was all done in mice, using very well-defined cancer mutations. In humans it’s going to be a much more complex state. 

‘But it does lead us to the following notion: Fasting is very healthy, but if you’re unlucky and you’re refeeding after a fasting, and you get exposed to a mutagen, like a charred steak or something, you might actually be increasing your chances of developing a lesion that can go on to give rise to cancer.’

There has been a health halo around intermittent fasting since it was popularized in the 2010s. More than one in ten Americans follow the eating regimen.

The diet sees a person limit their caloric intake to either certain hours of the day or days of the week — to lose weight and control eating habits.

Popular iterations include the 14:10 plan — where a person only eats within a 10-hour window — and the 5:2 — where someone eats five days a week and fasts for two.

Among celebrities who swore by the diet was Jennifer Aniston, who revealed in 2019 that she only consumes water in the mornings — saving her first meal until midday.

Mark Wahlberg is also a fan of the diet, limiting himself to eating from only 12 to 6pm every day.

Many have been drawn to the diet by its benefits, with studies linking it to weight loss, heightened concentration and even a longer life.

But experts are now also starting to uncover a wave of potential dangers associated with the diet.

Others have also suggested the diet is detrimental to the immune system, and can raise the risk of infections and heart disease.

In the new paper, published in the journal Nature, scientists looked at three groups of mice. 

One group fasted for 24 hours and ate what it wanted after that, one group fasted for 24 hours and did not eat and a third ate whatever it wanted throughout.

Fasting diets favored by celebrities may raise your risk of heart disease and cancer, a separate study has suggested (stock pic)

Scientists also extracted stem cells from the intestines of the mice during the experiment.

Intestinal stem cells are among the most active cells in the body, regularly rapidly dividing to replace the lining of the gut every five to ten days. 

They are also one of the most common sources of pre-cancerous cells.

Results showed that the cells multiplied most quickly in the fasted group after its 24-hour fast ended.

In a separate experiment, the team then turned on cancer-causing genes that made the mice more likely to develop tumors.

They found that mice who fasted and then ate had a higher risk of developing pre-cancerous polyps in their guts than the mice who ate normally or only fasted. 

Dr Shinya Imada, a biologist also involved in the research, added: ‘We think that fasting and refeeding represent two distinct stages.

‘In the fasted state, the ability of cells to use lipids and fatty acids as an energy source enables them to survive when nutrients are low.

‘And then it’s the postfast refeeding state that really drives the regeneration.

‘When nutrients become available, these stem cells and progenitor cells activate programs that enable them to build cellular mass and repopulate the intestinal lining.’