Tech A strange diet is designed to slow aging by mimicking fasting — but you can eat normally most of the time

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Evidence suggests fasting could help prevent aging. One researcher says the fasting-mimicking diet offers similar benefits with fewer restrictions.

Intermittent fasting works at least as well as other forms of dieting for weight loss. play

Intermittent fasting works at least as well as other forms of dieting for weight loss.

(Shutterstock/Siberian Photographer)

  • Evidence suggests that fasting could help cure disease and prevent aging, though a number of fasting interventions sound difficult and unpleasant.
  • One researcher has developed the fasting-mimicking diet, which he says could provide the benefits of fasting but only requires eating a specific way for five days at a time once every few months.
  • Still, eating healthily and exercising are important for people who want to reduce disease risk and prevent aging.


Most of us don't just want to live longer. We want stay healthier at the same time — an extra 20-30 years lying in a sickbed sounds terrible.

Valter Longo, the director of the Longevity Institute at the University of Southern California, believes that by eating in a specific way, people might be able to live past 100 without developing debilitating diseases.

There's solid evidence that suggests periodic fasting could prolong lifespan and prevent disease. Longo has designed a diet that he says provides the benefits of fasting while still letting people eat normally most of the time.

Longo explains his fasting-mimicking diet (FMD) in his new book, "The Longevity Diet." It's designed to provide the benefits of fasting while only having people cut back on food for five days at a time. These fasts can be done as often as once a month or as infrequently as once every six months. Most people could theoretically reap the benefits by doing the fast three or four times a year.

Studies — including at least one clinical trial with 100 participants — have found that this diet can significantly alter signs of disease, reduce weight and body fat, lower blood pressure, decrease levels of biomarkers associated with cancer, and improve blood-sugar levels.

Longo advocates for healthy eating even when you aren't on the diet. play

Longo advocates for healthy eating even when you aren't on the diet.

(Shutterstock)

The fasting-mimicking diet

People on the FMD eat normally for 25 days, but the five-day fast portion is no joke.

On those days, participants eat a specific blend of nutrients that amount to 1,100 calories on the first day and 800 calories per day on days two through five.

Nutritionally, most of these calories come from complex carbohydrates (like vegetables), healthy fats (olive oil), and plant-based protein (from nuts).

Although it's still far too early to say whether doing the FMD every so often will actually prolong life in the long term, the basic idea is appealing. Fasting is known to trigger physical changes that seem to be associated with longer life and disease prevention. Early clinical trials indicate that restricting calorie intake seems to trigger similarly promising physical changes in people, which is why it's sometimes discussed as a potential anti-aging intervention.

But as Longo explains in the book, calorie restriction usually involves reducing caloric intake by 20-30%, which sounds kind of miserable in the long term. And animal and human studies suggest that many of the physical changes associated with fasting start during a shorter fast.

Longo used that data, along with other anti-aging studies, examinations of how centenarians eat and live, and the clinical trials conducted so far, to design the FMD to provide "the benefits of fasting without the deprivation and hunger" (except for that five-day period).

Longo also created a company that sells the meals people consume while on the fasting portion of the diet, though he says 100% of his shares in that company and all profits from the book go to a non-profit foundation he created that's dedicated toward research on treating and preventing disease.

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(sportpoint/Shutterstock)

Living a healthy life

The studies conducted so far have allowed people to eat whatever they pleased for the 25 non-fasting days, but Longo emphasizes in the book that science supports certain eating plans regardless.

Most research indicates that the people who live longest and stay healthy tend to eat a largely plant-based pescatarian diet that's relatively low in protein. Longo thinks this is ideal — a mostly vegan and fish-based lifestyle, though one in which moderate consumption of wine and coffee are permitted.

For someone in good health who is eating like this and getting regular exercise, he thinks the FMD might be beneficial to do twice a year.

For healthy people eating a more "normal" diet, he wrote that the FMD might be beneficial once every four or five months. People with at least two risk factors for cancer, diabetes, or heart disease who are overweight could consider doing the FMD once a month, Longo says.

You should talk to your doctor before any major diet or lifestyle change, especially since intense fasting can be dangerous for people who are pregnant or have diabetes or other health conditions.

Dietary interventions can have powerful effects, and a way to get the benefits of fasting without having to drastically cut calories all the time could be promising. But people who really want to become supercentenarians should probably pay attention to all aspects of your lifestyle.

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