Popular diet could raise risk of cardiovascular disease and cancer - study urges 'caution'

Fasting diets that skip breakfasts may compromise your immune system and put you at a higher risk of serious health problems, according to a new study.

By Diana Buntajova, Health Reporter based in London, specialising in personal stories, breaking news, and nutrition.

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From crispy cereals drowned in milk to eggs served on a slice of toast, the importance of eating breakfast has been undoubted for decades. However, popular diets built on fasting have questioned the timing of this meal, often instructing to simply skip it. Now, a new study warns that this practice could make you more prone to culprits like heart disease and cancer.

Time-restricted eating has experienced a boom in popularity, with faces like Gisele Bundchen, Jennifer Aniston, Kourtney Kardashian and Scarlett Johansson following the weight-loss trend.

The idea behind this food regimen relies on fasting for a certain number of hours each day or eating just one meal a couple of days a week.

While there are many different approaches to this popular diet, eating within an eight-hour window describes "daily time-restricted fasting".

Whether you follow a fasting protocol or you’re simply not a breakfast fan, it might be time for a change.

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Fasting diets could increase your risk of cancer and cardiovascular disease, study finds.

Fasting diets could increase your risk of cancer and cardiovascular disease, study finds. (Image: GETTY)

New research found that skipping meals, including breakfast, triggers a reaction in the brain that damages immune system cells.

The first study of its kind, published in the journal Immunity, sheds fresh light on the potential long-term effects of the fad.

Lead author Dr Filip Swirski, of Icahn Mount Sinai, New York, said: "There is a growing awareness that fasting is healthy, and there is indeed abundant evidence for the benefits of fasting.

"Our study provides a word of caution as it suggests that there may also be a cost to fasting that carries a health risk.

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"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."

Looking at mice divided in groups, the researchers gave breakfast, the largest meal of the day, to one group right after waking up while the other went without.

The team then identified a difference in the number of monocytes - white blood cells made in bone marrow that fight infections, heart disease and cancer.

At the start of the study, the animal models had the same amount but 90 percent disappeared from the bloodstream four hours after fasting in the group that went hungry, with a further decline at eight hours.

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Skipping meals, including breakfast, triggers a reaction in the brain that damages immune system cells.

Skipping meals, including breakfast, triggers a reaction in the brain that damages immune system. (Image: GETTY)

Scans showed the monocytes travelled back to the bone marrow to hibernate. 

The researchers continued to fast mice for up to 24 hours and then reintroduced food.

After having food again, the cells hiding in the bone marrow surged back into the bloodstream within a few hours.

This led to heightened levels of inflammation, suggesting that they made the body more vulnerable instead of protecting it against infection.

Further analysis showed specific regions in the brain controlled the monocyte response during fasting and elicited a stress response dubbed “hangry” - a term that combines feelings of being hungry and angry.

Fasting in mice led to heightened levels of inflammation.

Fasting in mice led to heightened levels of inflammation. (Image: GETTY)

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 to 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.

"Because these cells are so important to other diseases like heart disease or cancer, understanding how their function is controlled is critical."

However, the caveat of the research is that it was conducted on mice models and not humans.

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