Fasting, Diets and Nutrition

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With nearly three-quarters of adults over age 20 either overweight or obese, chances are someone you know (or you) is looking for a weight loss plan. Intermittent fasting (including very low-calorie plans) is not a new approach but generates renewed buzz from time to time. Could it work?

Intermittent fasting takes many forms. It can be alternate day fasting (typically a feast day alternated with a fast day of 500 calories eaten at one meal), the so-called 5:2 plan (5 days of unrestricted eating, 2 days of calorie restriction), time-restricted eating (eating within a certain time frame, perhaps 10 hours, and fasting outside that window), or 24-hour fasts, also known as the one meal a day (OMAD) diet.

Facts on Fasting

In recent years, researchers have taken a closer look at the approach. University of Chicago researchers reviewed more than 25 research studies and summarized the effects of the various forms, concluding that the approach is generally safe and can have good effects on blood pressure, cholesterol and insulin resistance (good to lower diabetes risk). They found that this approach can help you reduce calories by 10 to 30% and produce mild to moderate weight loss, up to 8% of your starting weight.

However, other researchers also reviewed the findings of fasting research and concluded that while studies do suggest benefit, research is scarce on whether it works long-term for weight loss. The researchers, including Caroline Apovian, MD, co-director of the Center for Weight Management and Wellness at Brigham and Women’s Hospital, Boston, say that continuous calorie restriction—what we all know as a daily weight loss plan—may be just as effective as intermittent fasting.

Some approaches are better than others. If you do decide to do intermittent fasting, one way, Apovian says, is to ”eat during the daylight hours so that you are eating over 8 to 10 hours and stop at 5 p.m.” It is not technically a fast, but a way to curtail eating—and nibbling—day and night, which will reduce total calories.

Another expert, James Betts, PhD, professor of metabolic physiology at the University of Bath in the U.K. also reviewed the research on intermittent fasting and meal timing. ”Our research shows no special metabolic benefit of intermittent fasting beyond other forms of restricting the diet.  In fact, it can make a person become less active and lose lean tissue mass.”

“Perhaps just having certain times of day when food is avoided may be a happy medium for older people—for example, avoiding food late in the evening.”

He is wary about suggesting these plans to older adults, especially if they follow the approach involving a long duration without food. His bottom line: “Perhaps just having certain times of day when food is avoided may be a happy medium for older people—for example, avoiding food late in the evening.”

What about very low-calorie diets, keeping your intake to 800 calories a day or so? “Very low-calorie diets are not meant for longer than three-four months,” Apovian says. And you can’t meet nutritional needs on those, she warns. Meeting nutritional needs on an intermittent fasting plan where  you eat from about 8 to 5 is not an issue, she says.

Fasting Faults

“…people who take heart or blood pressure medications may be more likely to suffer dangerous imbalances in potassium and sodium when they’re fasting”

A publication of the Harvard Medical School says a fasting diet may not be right for every older person. It reports a concern of Dr. Suzanne Salamon, associate chief of gerontology at Harvard-affiliated Beth Israel Deaconess Medical Center: “People who need to take their medications with food — to avoid nausea or stomach irritation — may not do well with fasting. Also, people who take heart or blood pressure medications may be more likely to suffer dangerous imbalances in potassium and sodium when they’re fasting.”

Intermittent fasting may also be harmful if you have diabetes and need food at certain times or take medication that affects your blood sugar.

What about Nutritional needs?

Experts say that intermittent fasting among people who already follow a healthy diet poses no specific additional needs, although some consider supplements a good option, as this article points out. At any rate, as with any diet, common sense nutrition rules still apply:

  • Drink plenty of water
  • Choose healthy fats and grains
  • Choose clean protein; avoid processed foods
  • Choose low-fat cooking methods (no frying)
  • Eat a variety of fruits and vegetables

…and as always, consult with your doctor before starting any diet regimen, including fasting.

Want more info?

For more information on intermittent fasting, here’s an overview from AARP and here’s the 2022 U.S. News and World Report rankings.

Want to know more about diet and nutrition?  Stay tuned for information on Senior Planet’s talk by a nutritionist!  Meanwhile, join us for live virtual fitness classes, lectures and discussion groups on health topics. Learn more here

This article offered by Senior Planet and Older Adults Technology Services is for informational purposes only and is not intended to substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding any medical condition. If you think you may have a medical emergency, call your doctor or 911 immediately.


Photo: Shaun Newton

Kathleen Doheny is a Los Angeles-based independent journalist, specializing in health, behavior, fitness and lifestyle stories. Besides writing for Senior Planet, she reports for WebMD, Medscape, Endocrine Web, Practical Pain Management, Spine Universe and other sites.  She is a mom, mother-in-law and proud and happy Mimi who likes to hike, jog and shop.