These days, intermittent fasting is a household phrase, but back in 2002 when The Warrior Diet was first published, the idea of eating only during specific windows of time was a pretty new idea. Like paleo and similar diets, this eating plan is based on emulating the ways that our ancestors supposedly ate. In the case of the warrior diet, however, the emphasis involves not just what but also when our forebears were eating.

As with any intermittent fasting plan, the warrior diet limits the times during the day when you are permitted to eat, advocating a single meal a day. But is this way of eating effective for losing weight, and more importantly, is it safe and sustainable in the long term? This guide will tell you everything you need to know.

The warrior diet is based on a book of the same name written by Ori Hofmekler, and it claims to “switch on your biological powerhouse for high energy, explosive strength, and a leaner, harder body.”

The plan is a version of intermittent fasting that alternates a period of fasting with a small window of time in which to eat all of the day’s calories. The warrior diet promotes exercising and undereating during the day, when our nomadic and hunter-gathering ancestors would likely be busy finding food rather than eating it. For exercise, the diet encourages short workouts that emphasize strength training, especially for your joints and back, and high-velocity exercises such as jumps, kicks, and sprints.

During the day, raw vegetables and fruit, small amounts of protein, and beverages including water, natural juices, coffee, and tea are permitted. The book states that this period should not last more than 16 to 18 hours, but many newer variations of the diet encourage undereating or not eating at all for 20 hours.

Then in the evening, you eat one large meal. There are no restrictions on how much or what kind of food you eat, so you can include any protein, fat, and carbs you want.

The diet claims that fasting produces fat-burning hormones, allows your body to use protein more efficiently, stabilizes your blood sugar levels, increases testosterone and growth hormone levels, and allows amino acids to act favorably on the brain. Consequently, at the end of the undereating phase, your body is positioned to eat a lot of food without gaining body fat. The author writes, “This is the best time to eat as much as you want and enjoy this wonderful sense of freedom.”

Diets that are centered around intermittent fasting, like the warrior diet, may also put your body into ketosis, according to research published in October 2017 in Ageing Research Reviews. Ketosis, the basis of the keto diet, is a metabolic state in which your body gets its fuel from fat rather than sugar.

But experts are skeptical about the benefits of the warrior diet. “The plan encourages a swing from starvation to bingeing, and it’s not really something a body could or should withstand without consequence. It makes your body either starve and feel really deprived, or it makes your body work so hard to try to get rid of that giant eating binge,” says Bonnie Taub-Dix, RDN, author of Read It Before You Eat It: Taking You From Label to Table.

No research has specifically studied the warrior diet. But scientists have identified some potential health benefits of intermittent fasting:

It’s not clear whether the warrior diet would confer the same benefits as other types of intermittent fasting. And even if it does, this trendy version of the diet might not be your best choice. “I don’t want to discount intermittent fasting, because there’s some good research behind it,” says Samantha Cassetty, a registered dietitian based in New York City and the coauthor of Sugar Shock. “But this is an extreme version where you’re only eating in a small window. It’s unhelpful, unrealistic, and unsustainable for most people.”

It’s possible to lose weight on the warrior diet since you might be taking in fewer calories. Intermittent fasting can lead to weight loss, according to a review and meta-analysis of six studies, however, it wasn’t more effective than reducing calories without timing your meals.

“If you’re doing this diet for weight loss, the reason it might be working is because it is reducing your calorie load. There’s no magic to it,” Cassetty says.

It can be difficult to eat a day’s worth of calories or more in a short window of time. Of course, it isn’t impossible to do so, and you could also gain weight if you eat an excessive amount during your daily window, Taub-Dix points out.

In general, the diet does not restrict foods or food groups, although it does emphasize whole, unprocessed foods whenever possible. During your daytime undereating phase, if you feel you need to eat something, you can have:

During the diet’s eating window, it is recommended that you start your meal with raw vegetables, then add protein and cooked veggies, and finally whole-grain carbohydrates. Include a variety of tastes, textures, aromas, colors, and temperatures. You can eat:

Refined sugar and refined, processed pastries are not allowed on the warrior diet.

On the warrior diet, you might eat raw vegetables and fruits and a little bit of protein during the day, then a green salad and one of these larger meals at night.

Curry chicken in tomato broth, steamed vegetables, and low-carb pumpkin cheesecake

Baked red snapper, zucchini fries, and crepe blintzes

Pepper beef and broccoli and warm raspberries with yogurt

Egg white omelet with black beans and berries with maple syrup and red wine

Angel hair rice pasta with tomato sauce and eggs and papaya gelatin

Turkey-stuffed peppers and a green citrus smoothie

Chicken chipotle flatbread and low-carb pecan pie

The warrior diet isn’t expensive. It doesn’t require you to buy specific products, so it shouldn’t add to your grocery budget. And it’s not that complicated — you don’t have to count calories or macros, or track your food.

It’s not for everybody, however. Taub-Dix says that it’s particularly risky for people with disordered eating, people with diabetes, children, women who are pregnant or lactating, and older adults. She doesn’t recommend it for anyone, and she says if you want to try it, you should talk to your doctor or dietitian first.

If you decide to try the warrior diet, you may need to figure out how you’ll manage social situations and family activities that include meals outside of your eating time. “When any eating plan restricts you from socializing or enjoying meals with friends and family, I think that’s a red flag,” Cassetty says.

The small window of eating time may make it difficult to get the nutrients you need. Cassetty pointed to protein, which ideally you want to eat throughout the day to help rebuild your muscle tissue. “This type of calorie restriction can also trigger stress, make you preoccupied with food, make you hungry and irritable, and promote headaches,” she says. And if you have kids, it’s not a good eating plan to model for them, since it signals that there’s something wrong with eating meals at routine times.

It might be hard to time your exercise with your eating. “If you’re exercising in the morning, that could put you at risk of fainting, dizziness, nausea, headache, or injuring yourself,” Cassetty says.

And if you’re going to restrict your eating time, eating earlier in the day is preferable since that’s when your metabolism is most efficient, according to a study published in March 2021 in Biomolecules.

'The Warrior Diet: Switch on Your Biological Powerhouse for High Energy, Explosive Strength, and a Leaner, Harder Body'

This is the original book that launched the warrior diet

Use this app to track your intermittent fasting meal windows.

This site has a host of resources to try if you’re following the warrior diet.

The Warrior Diet Episode on 'The Intermittent Fasting Podcast'

Take an hourlong dive into the ins and outs of the warrior diet.

The warrior diet is a type of intermittent fasting that mimics the eating patterns of our warrior ancestors, who ate little or nothing during the day and filled up in the evenings. It features a daily cycle of undereating and overeating. If you want to try intermittent fasting, dietitians prefer versions that aren’t as strict.

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