The idea that cutting calories is good for health isn’t especially new, so why then is fasting still somewhat controversial?

More and more studies have hinted that reducing calories, even just on two days of the week, can have significant benefits, not only for weight-loss but for the risk of chronic disease.

A new study puts it even more strongly: Fasting reduces the risk for obesity, diabetes, heart disease, and cancer. It may even help repair cellular damage.

The findings are from a research team that included Michael Mosley, the developer of the “Fast Diet,” also called the 5:2 diet. On Mosley's diet, people eat normally for five days of the week and then fast (or nearly fast) for two nonconsecutive days.

Fasting provides several benefits, including increasing insulin sensitivity and reducing levels of insulin and leptin, the hormone that regulates how hungry we are and how fat is stored in the body.

The study considered previous evidence on the effects of different versions of calorie restriction in both animals and people.

Fasting had a wide range of heath benefits for both body and brain. Intermittent fasting increased the amount of antioxidant enzymes, which help repair cellular damage. In this way it is also linked to a reduction in the cellular processes that can trigger Alzheimer’s disease and Parkinson’s disease.

Intermittent fasting has been linked to increased levels of bone-derived neurotrophic factor (BDNF), which helps generate new neurons in the hippocampus, the area of the brain that governs learning and memory.

And it was also shown that intermittent fasting protects against heart attack and reduces the risk of cancer. In animals, certain cancers, like neuroblastoma, breast, and ovarian cancers, actually decreased in size after intermittent fasting was begun.

Metabolically, fasting provides several benefits, including increasing insulin sensitivity and reducing levels of insulin and leptin, the hormone that regulates how hungry we are and how fat is stored in the body. These changes could greatly lower the risk for obesity, in addition to improving a person’s metabolic profile.

Finally, intermittent fasting was linked to a reduction in inflammation, which is critical, the researchers write, since just about all major diseases, including heart disease, cancer, diabetes, neurodegenerative diseases, and arthritis, are highly dependent upon inflammation. Researchers have shown that switching to an intermittent fasting diet significantly reduced the markers of inflammation that are linked to cancer and other chronic diseases.

Another way to get the benefits of fasting might be to skip breakfast or lunch on certain days of the week.

Humans have only been eating three meals a day in recent history. For most of our evolution, the authors point out, eating was much less scheduled. Hunting and gathering made for unpredictable meals, especially depending on the season, so going without food, or with very little food, for a day or two at a time was fairly common.

The three-meals-a-day pattern came with the agricultural revolution in the last 10,000 years, and we are obviously very wedded to it now. The challenge will be to get people who are so used to the three-meal-a-day routine to shift habits.

Doctors may want to “prescribe” brief periods of fasting to their patients, the authors say, given the amount of recent evidence as to its benefits. The authors point out that fasting doesn’t have to mean zero calories in a day — on the 5:2 diet, for instance, the two days of fasting allow for up to 500 calories to be consumed on the “fasting” days.

Another way to attain the benefits of fasting might be to skip breakfast or lunch on certain days of the week.

Talk with your doctor to make sure you’re healthy enough to try fasting, but for many people it may be a smart way to keep your weight in check, while also reducing the risk of the most common chronic diseases.

The study was carried out at the National Institute of Aging and Johns Hopkins University. It was published in the journal Proceedings of the National Academy of Sciences.