Here’s what experts say about the benefits—and risks—of intermittent fasting

Here’s what experts say about the benefits—and risks—of intermittent fasting

“Then what are you going to do with the dish?”

My annual exam went well and the doctor asked about my diet. “A little moderate of everything?” I said, shrugging; then I replied, “What to do your do around the meal?”

“Well,” replied the doctor, “I practice intermittently fast.”

Over the years I have heard the hype about how fasting can help maintain a healthy weight and potentially prevent everything Alzheimer’s disease to sleep apnea to Cancer. But it was the sight of my energetic, razor-sharp doctor – who’s my age but doesn’t look anywhere near it – that was the most compelling argument for fasting I’ve ever seen.

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As someone who has never uttered the line “I forgot to eat,” who carries granola bars around specifically to quell hunger pangs, I considered myself as likely a meal-skipping candidate as you could ever find. And the information there about intermittent fasting seemed so confusing, so contradictory, that I wasn’t sure where to start. Do you restrict certain types of food? Do you only eat at certain times of the day? Some days you don’t eat at all? However, most important of all, I wanted to know: what do I really get out of it?

As it turns out, quite a bit… maybe.

“With intermittent fasting, it’s not what you eat, but when,” he says Elizabeth Ward, a registered dietitian and nutrition consultant in the Boston area. “With no calorie restrictions or special foods to make or buy, IF (intermittent fasting) is more of a lifestyle than a prescribed diet.”

However, the way this is done can be flexible.

“There are several types of IF, including time-restricted eating and no or very little food for days at a time,” Ward continues. “On the 16:8 plan, only calorie-free drinks are allowed for 16 hours, and you eat during eight hour periods of your choosing. The 5:2 plan consists of eating as usual five days a week and consuming 25% of your daily calories (about 500 for women and 600 for men) on other days. Alternative day fasting (ADF), allows calorie-free drinks every other day of the week and eating on the remaining days.”

Most people discover IF because they are interested in losing or maintaining their weight, as it seems to promise dramatic and fast results. It’s definitely an easy way to limit calories and avoid less nutritionally dense foods.

“Breakfast in America tends to be a high-carb, high-sugar, high-calorie meal,” says New York City doctor James Stulman, a doctor at my local practice. “And then after 7 p.m., that’s a really challenging time. A lot of my patients, myself included, are hungry at 9:30 p.m. We’re snacking on cookies or something sweet. So if you’re disciplined enough not to eat after seven o’clock, you’re probably dealing with of all the nasty carbs, which are the real problem.”

But unlike other diets, intermittent fasting appears to offer real potential health benefits, as it triggers various processes that can make the body more efficient. A 2021 paper in the journal Nutrients explains: “As a result of periods of restricted food intake, the human body initiates a metabolic switch from glucose to stored lipids, leading to a cascade of metabolic, cellular and circadian changes which have been associated with numerous health benefits in animal models and humans. Periods of IF are not only associated with weight- and metabolic-related diseases, but also with reduced risk/prevalence of neurological diseases.”

And a widely circulated 2019 New England Journal of Medicine review of “Effects of Intermittent Fasting on Health, Aging, and Disease” reported that “a metabolic shift from glucose-based to ketone-based energy” may result “increased resistance to stress, increased longevity and reduced incidence of disease, including cancer and obesity.”

Intermittent fasting has been linked to a reduction in inflammation, which is believed to be a contributing factor in several chronic diseases.”

There is science to back up why intermittent fasting can be healthy for your cells. Christine Kingsley, Director of Health and Wellness lung institute and advanced nursing degree, explains that “during intermittent fasting, the body more efficiently achieves lower glucose levels, catalyzing the activation of brain synapses and resistance to stress. This allows the brain to function at its highest capacity humanly possible, which is why verbal memory improves significantly during and after exercise.”

There are other potential benefits.

Intermittent fasting also usually means that your body is not busy digesting during your resting hours. This can lead to better sleep, experts say.

One of the main effects is lowering insulin levels,” he says John Landry, Registered Respiratory Therapist and Company Founder and CEO Respiratory therapy zone. “Hhigh insulin levels are associated with an increased risk of chronic diseases such as diabetes and heart disease. By lowering insulin levels through intermittent fasting, individuals can reduce their risk of these conditions. Intermittent fasting has also been linked to a reduction in inflammation, which is believed to be a contributing factor in several chronic diseases.” He adds, “Currently, there is limited research on the effects of intermittent fasting on lung health. However, some studies show that intermittent fasting may have potential benefits for respiratory function, such as reducing inflammation and improving oxidative stress.”

Intermittent fasting also usually means that your body is not busy digesting during your resting hours. This can lead to better sleep, experts say.

“An IF schedule where the last meal is at least two to three hours before bed (caveat: for the general population, not for night shift workers) can support healthy sleep and optimal daytime energy in many ways,” he says. Chester Wucertified doctor of psychiatry and sleep medicine with a sleep and energy app TO GET UP. “It allows for better digestion, reducing the risk of heartburn and acid reflux that keeps you up at night.” Furthermore, he says, “when we sleep, our brain cleans up waste products. But if your body is busy digesting a meal, blood is diverted to the digestive system, leaving the brain with fewer resources to do this work.”

Regardless of the perceived benefits of IF, some people should never try it. As Elizabeth Ward explains, these include “people under 18 and over 75; pregnant and breastfeeding women; those on medication that must be taken with food at certain times of the day; people with chronic health conditions, such as kidney disease; people with a history of eating disorders .” She adds, “IF can be a trigger. Preoccupation with eating times can trigger obsessive food-related behaviors. Additionally, exercise lowers glucose and insulin levels, and people who rely on IF may need to change the intensity and timing of exercise to prevent fatigue .”

I might be intrigued by intermittent fasting, but my lifestyle isn’t realistically compatible with it right now. I could get by with just black coffee for breakfast, but I’m not ready for always early dinners yet. People who have families, who travel or socialize, or have irregular working hours would probably also struggle to stay on intermittent fasting. Any diet plan is only as good as your ability to stick to it. So for now, I will continue to be more careful about what I eat than when. “First and foremost,” says Dr. Stulman, “is your food choices.”

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