Nutrition / Food

What Is the 16:8 Diet and Does It Actually Work?

Here’s what you need to know.

You’ve probably heard of intermittent fasting. If so, you already have a basic understanding of the 16:8 diet.

The basis is to limit your eating to an eight-hour time frame and then nix food for the next 16 hours.

It’s intended to capitalize on your metabolism first thing during the day.

So you burn calories and fat while you’re active. With the 16:8 diet, you’re not necessarily changing what you’re eating—just when you choose to eat.

Our experts dig into the details of the 16:8 diet and explain whether it works.

What is the 16:8 diet, and how does it work?

“16:8 is a version of intermittent fasting,” explains Aaptiv Trainer Jennifer Giamo.

“You fast for 16 hours (about half of that is spent asleep). Then you eat for the other eight hours. Meaning, after your last meal of the day, perhaps dinner at 7 p.m., you wouldn’t eat again until 11 a.m. the next day. You’re still eating like you would during any day, but only in between that set time span.”

Think of it more like a dieting pattern versus a specific diet. With fasting, Giamo says, your body is depleted of readily available glucose and stored glycogen.

This causes it to turn to your fat stores for energy—similar to the ketogenic diet. That’s why people may use the 16:8 approach as a tool for weight loss, due to decreased overall caloric intake.

“Intermittent fasting is when you confine your eating to only a certain number of hours a day,” says Maggie Berghoff, a nurse practitioner and functional medicine clinician.

“There are lots of different ratios, but 16:8 is most common. This means that for 16 hours out of 24, you don’t eat (but you do consume water). Then for eight hours, you eat as you are hungry. It’s super-helpful because a shorter window of eating means a longer time the body has to focus its efforts on healing the body and providing it energy, rather than breaking down, processing, and absorbing your food.”

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Are there benefits?

According to holistic wellness practitioner Audrey Christie, any intermittent fasting pattern can speed up weight loss and reduce inflammation in the body.

It may also increase energy, improve sleep, lessen brain fog, and minimize your risk of major chronic diseases. Berghoff agrees, noting that fasting helps increase your metabolism, gives your gut a chance to rest from digestion, and boosts energy production.

For the 16:8 diet specifically, one study found that in a 12-week period, adults who practiced time-restricted eating lost a small amount of body weight and saw improvements in blood pressure.

Outside of that, most research centers on fasting in general, says Sandra LaMorgese, Ph.D., a holistic nutritionist who has lost more than 50 pounds by practicing intermittent fasting.

Studies say fasting can promote the production of a brain protein that helps with memory and stress management, preserve tissues and organs in the body, and even support the process of autophagy, which essentially recycles damaged parts of cells.

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What are some of the disadvantages?

“The key thing with fasting is that for it to work, you need to not eat anything. Whereas in real life, little extras slip in, which negate the benefits,” Giamo says.

“As such, for the 16:8 diet to be effective, you will need to consume a substantial meal at some point during the day so that your hunger does not get the better of you. It’s also likely that fasting can put your body into a state of ketosis (without actually having to do the keto diet!). [This] is when your body starts burning fat for energy instead of carbs. In some cases, this can impact weight loss.”

But the 16:8 isn’t an instant fix for weight loss, Christie warns. This may be tricky for those seeking immediate results.

Berghoff notes that if you already have a fast metabolism, you may not feel great with this style of eating. You may want or need to eat more regularly based on the time of day.

She also advises against the 16:8 diet for anyone with a history of any eating disorder because limiting when to eat can encourage restrictive behaviors such as overeating and binge eating.

Pay close attention to meals around workouts.

Additionally, Giamo says, you’ll need to be mindful of what and when you eat to accommodate your exercise routine.

If you work out in the morning, plan for your first meal of the day. Make sure to include plenty of protein, complex carbs, healthy fats, and fiber throughout your eating window to stay energized.

“Depending on the intensity of the workout, you may want to build your glycogen stores with complex carbs for dinner the night before. [This way] you have readily available energy for a cardio workout,” Giamo suggests.

“I don’t like to do cardio on a full stomach. The sudden demand for blood flow from the muscles will steal vital blood flow needed for digestion and assimilation of nutrients. The key here is to plan ahead, so your nutrition can meet the demands required by the intensity of your workout. Listen to your body. If you feel lightheaded and dizzy during a workout, then you need to fuel your body. The more intense the workout, the more complex carbs are needed. On rest days or low-intensity days, more protein and fiber is required.”

Above all, start slowly when exploring the 16:8 diet. Additionally, always check in with your health care provider to make sure it fits your dietary or health needs.

From there, Berghoff says, you can play around with the timing of eating and fasting to reach a balance that fits your body, energy, lifestyle, and goals.

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