Fasting Diets Are Gaining Acceptance

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Source: The New York Times

Mark Mattson, a neuroscientist at theNational Institute on Aging in Maryland, has not had breakfast in 35 years. Most days he practices a form of fasting — skipping lunch, taking a midafternoon run, and then eating all of his daily calories (about 2,000) in a six-hour window starting in the afternoon.

“Once you get used to it, it’s not a big deal,” said Dr. Mattson, chief of the institute’s laboratory of neurosciences. “I’m not hungry at all in the morning, and this is other people’s experience as well. It’s just a matter of getting adapted to it.”

In a culture in which it’s customary to eat three large meals a day while snacking from morning to midnight, the idea of regularly skipping meals may sound extreme. But in recent years intermittent fasting has been gaining popular attention and scientific endorsement.

It has been promoted in best-selling books and endorsed by celebrities like the actors Hugh Jackman and Benedict Cumberbatch. The late-night talk show host Jimmy Kimmel claimsthat for the past two years he has followed an intermittent fasting program known as the 5:2 diet, which entails normal eating for five days and fasting for two — a practice Mr. Kimmel credits for his significant weight loss.

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CreditGary Taxali

Fasting to improve health dates back thousands of years, with Hippocrates and Plato among its earliest proponents. Dr. Mattson argues that humans are well suited for it: For much of human history, sporadic access to food was likely the norm, especially for hunter-gatherers. As a result, we’ve evolved with livers and muscles that store quickly accessible carbohydrates in the form of glycogen, and our fat tissue holds long-lasting energy reserves that can sustain the body for weeks when food is not available.

“From an evolutionary perspective, it’s pretty clear that our ancestors did not eat three meals a day plus snacks,” Dr. Mattson said.

Across the world, millions of people fast periodically for religious and spiritual reasons. But some are now looking at the practice as a source of health and longevity.

Valter Longo, the director of the Longevity Institute at the University of Southern California, initially studied fasting in micethat showed that two to five days of fasting each month reduced biomarkers for diabetes, cancer and heart disease. The research has since been expanded to people, and scientists saw a similar reduction in disease risk factors.

Dr. Longo said the health benefits of fasting might result from the fact that fasting lowers insulin and another hormone called insulinlike growth factor, or IGF-1, which is linked to cancer and diabetes. Lowering these hormones may slow cell growth and development, which in turn helps slow the aging process and reduces risk factors for disease.

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