How the New 5-Day ‘Fasting’ Diet Works

7/2/2015
Updated:
7/2/2015

A new study from the University of Southern California shows that restricting calories just five days a month for three months:

  • helped people lose weight,
  • reduced a number of risk factors for cancer, diabetes and heart attacks, and
  • improved markers for living a longer life and tests for immune function

The study author, Valter D. Longo, says that “the research demonstrates the first anti-aging, healthspan-promoting intervention that doctors could feasibly recommend for patients.”

The Study

Thirty-seven men and women participated in the three-month study. For 25 days in each month, they all ate their normal diets. For the other five days each month, 19 of the subjects restricted calories to between one third and one half of their normal intake (the fasting group), while the other 18 continued to eat their regular diet and did not restrict calories (the control group). The fasting group was fed 1,090 calories on the first “fast” day and 725 calories per day for the other four “fast days”. Their food on these days consisted of vegetable soups and chamomile tea.

The fasting group had a reduction in risk factors linked to aging, heart attacks, diabetes and cancer, including weight loss.(Pablo Blazquez Dominguez/Getty Images)
The fasting group had a reduction in risk factors linked to aging, heart attacks, diabetes and cancer, including weight loss.(Pablo Blazquez Dominguez/Getty Images)

How Might Intermittent “Fasting” Prolong Life?

Nobody really knows whether intermittent low-calorie diets help to promote weight loss and to prevent disease, but after three months of this regimen, the fasting group had a reduction in risk factors linked to aging, heart attacks, diabetes and cancer, including lowered blood glucose, reduced markers of inflammation and weight loss.

In similar studies, humans and animals have had a marked lowering of a hormone called Insulin-Like Growth Factor-1 (IGF-1), high levels of which increase risk for cancer and premature death. Intermittent low-calorie diets have been shown to extend the lives of yeast and mice. Mice in an intermittent fasting program had less belly fat which helped protect them from developing diabetes, more brain nerve growth promoting memory, and lower IGF-1 levels. Other studies published this year show that periodic fasting helps to prevent diabetes in those who are at high risk.

Weighing yourself daily is one of the most effective ways to track your weight and do something immediately (AndreyPopov/iStock)
Weighing yourself daily is one of the most effective ways to track your weight and do something immediately (AndreyPopov/iStock)

Weigh Yourself Every Day

Another study found that weighing yourself daily is one of the most effective ways to track your weight and do something immediately to help you lose weight or prevent weight gain. Weigh yourself at the same time of day each morning. If you are trying to lose weight, use your scales to monitor your progress. If you are trying to prevent weight gain, add a “fast” day whenever your scales show that you have gained a pound or more.

Gabe Mirkin, M.D., has been a practicing physician for over 50 years. He is board-certified in sports medicine, allergy and immunology, pediatrics, and pediatric immunology. This article was originally published on DrMirkin.com. Subscribe to his free weekly Fitness & Health newsletter.  

Sports medicine doctor, fitness guru and long-time radio host Gabe Mirkin, M.D. brings you news and tips for your healthful lifestyle. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. He is one of a very few doctors board-certified in four specialties: Sports Medicine, Allergy and Immunology, Pediatrics and Pediatric Immunology.
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