Skipping breakfast may raise your risk of infections, heart disease and cancer, according to a new study.
Scientists at Mount Sinai hospital in New York found that starving the mice for a day caused the immune cells to rush inside the bone marrow.
But, when the mammals ate again, the cells cascaded back out into the bloodstream setting off higher levels of inflammation.
Dr Filip Swirski, an immunologist who led the study, said: ‘Because [immune cells] are so important to other diseases like heart disease or cancer, understanding how their function is controlled is critical.’
Fasting diets favored by celebrities may raise your risk of heart disease and cancer, a study has suggested (stock pic)
Jennifer Aniston (right) and Mark Wahlberg are both fans of the intermittent fasting diet. But a study by scientists at Mount Sinai in New York has suggested fasting could raise your risk of heart disease and cancer
Intermittent fasting — which means eating within a strict time window or skipping meals entirely — became one of the hottest diet tools in the early 2010s.
Supporters suggest the diet prompts weight loss, lowers inflammation levels and can help people live longer. But a growing body of evidence has suggested that it may actually damage people’s health.
Dr Swirski said: ‘There is a growing awareness that fasting is healthy, and there is indeed abundant evidence for the benefits of fasting.
‘[However], our study provides a word of caution as it suggests that there may also be a cost to fasting that carries a health risk.
‘This is a mechanistic study delving into some of the fundamental biology relevant to fasting. The study shows that there is a conversation between the nervous and immune systems.’
In the paper, scientists split mice into two groups. One group received breakfast — the rodents’ largest meal of the day — while the other group went without.
Scientists drew their blood at the start of the study, and at four, eight and 24 hours into the experiment, and. Samples were tested for monocytes — white blood cells made in the bone marrow that fight infections, heart disease and cancer.
At the outset, all the lab rodents had the same number of these cells in their bloodstreams.
But after four hours, the fasting group saw 90 percent of these cells disappear. There was a further decline at eight hours.
Scans showed that the cells had migrated back to the bone marrow. Production of new monocytes in this area also diminished.
The fasted mice were denied food for 24 hours, before finally being allowed to have a meal again.
When this happened, however, the white blood cells surged back into the bloodstream and sparked inflammation.
Further analysis revealed that when the mice were hungry it prompted a stress response in the brain — dubbed by humans as ‘hangry’, or feeling hungry and angry.
This triggered the white blood cells to move to the bone marrow and once it was relaxed they were able to return to the bloodstream.
Dr Swirski said: ‘The study shows that, on the one hand, fasting reduces the number of circulating monocytes, which one might think is a good thing, as these cells are important components of inflammation.
‘On the other hand, the reintroduction of food creates a surge of monocytes flooding back into the blood, which can be problematic.
‘Fasting therefore regulates this pool in ways that are not always beneficial to the body’s capacity to respond to a challenge such as an infection.’
Pictured above is Mark Wahlberg’s daily routine, which involves fasting for 18 hours
Scientists warned that the study had not been carried out in humans, so was not directly comparable.
Intermittent fasting diets have become popular in recent years as effective weight loss regimes.
Advocates have also claimed they can reduce inflammation in the body, which could lower the risk of conditions including Alzheimer’s disease. arthritis and asthma among others.
Among celebrities swearing by the diets is Jennifer Aniston, who revealed in October 2019 that she only consumes liquids in the mornings — saving her first meal until midday.
Mark Wahlberg is also a fan of the diet, limiting himself to only eating food between 12pm and 6pm every day. Our reporter Luke Andrews tested living like Mark Wahlberg for a month and found fasting in the mornings to be a struggle.
Evidence is gradually mounting that intermittent fasting diets can also pose risks to people’s health, however.
The American Heart Association advises that altering meal frequency may not be useful.
The study is published in the journal Immunity. It received funding from the National Institutes of Health and the Cure Alzheimer’s Fund, a non-profit that funds research into methods to prevent or slow the progress of the debilitating disease.
What is intermittent fasting?
Intermittent fasting involves switching between days of fasting and days of eating normally.
Intermittent fasting diets fall generally into two categories – time-restricted feeding, which narrows eating times to 6-8 hours per day, also known as the 16:8 diet, and 5:2 intermittent fasting.
The 16:8 diet is a form of intermittent fasting, also known as Time Restricted Eating.
Followers of the eating plan fast for 16 hours a day, and eat whatever they want in the remaining eight hours – typically between 10am and 6pm.
This may be more tolerable than the well-known 5:2 diet – where followers restrict their calories to 500–to-600 a day for two days a week and then eat as normal for the remaining five days.
In addition to weight loss, 16:8 intermittent fasting is believed to improve blood sugar control, boost brain function and help us live longer.
Many prefer to eat between noon and 8pm as this means they only need to fast overnight and skip breakfast, but can still eat lunch and dinner, along with a few snacks.
When you do eat, it is best to opt for healthy options like fruits, vegetables and whole grains.
And drink water and unsweetened beverages.
Drawbacks of the fasting plan may be that people overindulge in the hours they can eat, leading to weight gain.
It can also result in digestive problems over the long term, as well as hunger, fatigue and weakness.