Review of intermittent fasting


By John DiTraglia



My pile of unread medical journals is very high. And it’s a LIFO pile – last in first out. So I was reading the April 30 issue of The New England Journal of Medicine the other day and came to the letters to the editor about a review article that had appeared in the Christmas 2019 issue. Then I fished out of my pile that issue and now I’m prepared to report on this interesting review of the new craze in healthy eating – intermittent fasting. (1,2)

It has been long known that calorie restriction and weight loss can lead to amazing extensions of the life span of animals. This would be great if it weren’t impossible to do because being hungry all the time is so hard. The mechanism was felt to be due possibly to a reduction in the damaging free oxygen radicals that occurs when the metabolic calorie burning engine runs hotter.

But now we are coming to understand that intermittent fasting might be even better for you and way more doable and it works in lots of ways that do not involve weight loss or reduced free radical production. For example two studies are mentioned in this review where approximately 100 obese women in each trial were assigned to either a intermittent-fasting regime or a 25% reduction in daily calorie intake. The women in the 2 groups lost the same amount of weight (not that much) during a 6 month period, but those in the intermittent-fasting groups had greater improvement in insulin sensitivity and a larger reduction in waist circumference.

It turns out that the way we eat three meals a day plus snacks and never get hungry was not natural during most of the time humans and most animals have been on earth. When we fast we flip a metabolic switch from using glucose for energy to using fat and ketones for energy. This has a long list of benefits that improves general health and reverses aging and many disease processes that you can read about here.

These authors finally give a prescription for gradually phasing into daily fasting for 16 to 18 hours each day or doing a restricted calorie intake 2 days each week. Children and people on insulin or diabetic meds should consult a physician or dietitian. I calculated that it might be possible for me to skip breakfast since I’m not hungry in the morning and then skip or eat very little lunch, together with sleeping 8 hours a night to accomplish 16 to 18 hours a day of fasting.

“The notion that breakfast is the most important meal is not supported by evidence.”

1. Correspondance N Engl J Med 2020; 382:1771-4.

2. de Cabo R, Mattson MP. Effects of intermittent fasting on health, aging, and disease N Engl J Med 2019; 381:2541-51.

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By John DiTraglia

John DiTraglia M.D. is a Pediatrician in Portsmouth. He can be reached by e-mail- jditrag@zoomnet.net or phone-354-6605.

John DiTraglia M.D. is a Pediatrician in Portsmouth. He can be reached by e-mail- jditrag@zoomnet.net or phone-354-6605.