Before You Try the Trendy Warrior Diet, You Need to Know the Downsides

Photo credit: Getty Images
Photo credit: Getty Images

From Good Housekeeping

One of the latest buzzy slim-down methods is the Warrior Diet, a form of intermittent fasting that is kind of, well, intense. Intermittent fasting is a way of eating in which you restrict what you eat (often fasting completely) during a set amount of time during the day, and chow down during only a certain number of hours. It's gotten a lot of attention over the past few years — and the Warrior Diet takes it to an extreme. Keep reading for a look into this diet, with advice from the Good Housekeeping Institute's Registered Dietician on whether or not it's a healthy plan to try.

What is the Warrior Diet?

First of all, though the Warrior Diet is trendy(ish) right now, it’s not new: It’s based on a book by Ori Hofmekler, first published in 2001 — and it’s worth noting that he’s neither a doctor nor a dietician. A former member of the Israeli Special Forces, he had an interest in nutrition and came up with this plan, which he claimed was based on the habits of ancient warriors. Also important to note: The Warrior Diet isn’t based on any sort of scientific research. Hofmekler's contention was that the diet would give you "high energy, explosive strength, and a leaner, harder body."

What Can You Eat on the Warrior Diet?

Basically, on the Warrior Diet you eat very little (and specific foods) for 20 hours out of the day, and for the other 4 hours you eat as much as you want, with no calorie limits. But there are limits on the types of things you can eat: Throughout the diet, processed foods are discouraged—so no candy, chips, fast or fried food, or sugar-packed drinks. "Although the diet does encourage more nutrient-dense foods, you’re technically allowed to eat whatever you want in the 4-hour feeding window as the emphasis is more on timing,” says Stefani Sassos, RDN, the Good Housekeeping Institute’s Registered Dietician. “But a tight feeding window, coupled with a laundry list of restricted foods, can make this diet difficult to start and sustain.”

In the book, Hofmekler outlined a 3-week phase in period:

Phase one is the “detox” week. During the 20-hour period, you can have small amounts of certain foods (like raw fruits and veggies, hard boiled eggs, dairy in small quantities), plus water, coffee, and tea. Then during the 4-hour eating period, it’s suggested that you have a salad with oil and vinegar, along with plant-based, preferably unprocessed, foods (like beans and cooked vegetables), and wheat-free grains.

During phase two (which also lasts one week), the foods in the 20-hour period stay the same, but some fats and protein (such as lean meats and nuts) are added during the 4-hour period. Grains are off the list this week.

During phase three, the third week, the 20-hour foods remain the same; for the 4-hour window, people alternate between higher and lower carb days over the course of the week.

After those three phases, Hofmekler suggested that people repeat the pattern of phase one/two/three. But those on the Warrior Diet often just follow a 20:4 pattern (eating very little or nothing, except during the 4-hour window) after completing the three phases, focusing on high protein and low carb foods and sticking with a low-processed diet.

Photo credit: Getty Images
Photo credit: Getty Images

What is the Simplified Warrior Diet?

In this version, the 20:4 breakdown stays the same — but during the 20-hours, people fast completely, and then eat whatever they want during the 4-hour window. As should be obvious, this is super-unhealthy: It encourages calorie restriction as well as binging on foods that may well have no nutritional value. In other words, people could end up eating too many calories and still not get the nutrients they optimally need. “Cramming a day’s worth of nutrition into four hours can be very difficult,” says Sassos, “and there’s also the issue of how much nutrition your body can absorb in one sitting. The biggest caveat with this approach, in my opinion, is that it can lead to a binge-restrict cycle and a negative relationship with food. And life happens: A social event or a work lunch may force you to break the fast, leaving you feeling defeated and prompting poor dietary choices since you already ‘fell of the wagon.’”

Are There Benefits to the Warrior Diet?

When it comes to intermittent fasting specifically, there have been a lot of reported upsides, including weight loss and improved blood pressure, blood sugar, and cholesterol, as well as reduced inflammation and improved brain health—but most of the research has been done on rats. Experts agree that more research on these benefits is needed on humans. Some studies on humans have found that as a weight-loss method, certain types of intermittent fasting are safe and effective, but not any more effective than other diets. None of these studies, however, focused on the extreme form of intermittent fasting that’s used in the Warrior Diet. (Other studies that are often cited to boost the supposed benefits of intermittent fasting were tiny with too few participants, were conducted on specific groups like trained athletes, or were conducted over a decade ago. Again, experts cite the need for additional research.) “Although there is quite a bit of research on the benefits of intermittent fasting — specifically the 16:8 method — there is nothing that supports the Warrior Diet specifically,” says Sassos.

The Downsides of the Warrior Diet:

From a nutritional stand point, the Warrior Diet isn’t an optimal choice. For one thing, a healthy diet includes a variety of nutrients, and it can be hard to achieve that during the limited time frame when one is allowed to eat. And when you don’t get enough nutrients in your diet, your immune system and your energy levels, among other things, take a hit. “Many people lose weight on intermittent fasting diets because they are simply eating less calories overall in their feeding window,” says Sassos. “And with a super restrictive time frame like 4 hours, it can be difficult to get 100% of your macronutrient and micronutrient needs in. If you’re going to try the Warrior Diet, for certain you should be taking a multivitamin to make sure you’re at least meeting basic vitamin and mineral quotas for the day. And try your best to get a wide variety of nutritious foods from all food groups during feeding time.”

While the Warrior Diet itself hasn’t been studied, research on various types of intermittent fasting has shown that it can bring on disordered eating in some people, as well as menstrual irregularities and mental-health issues such as depression. “While I do believe that sticking to a time to fast overnight can be beneficial, the Warrior Diet takes restricted timing to a whole new level and can have some pretty scary side effects, like low blood sugar, fatigue, and digestive issues,” says Sassos. You may end up constipated; and if your blood sugar is knocked askew, it can bring on brain fog and irritability, among other things.

Another downside: This type of restricted eating can be very hard to work into one’s everyday life, which may include family and social occasions, and just being a person in the world. And of course, it can be hard to stick to a strict diet when one’s hunger pangs are sending them a signal to eat!

The Role of Exercise in the Warrior Diet:

In the original book, Ori Hofmekler included workout recommendations — specifically, both strength and speed training. If you’re fasting or restricting calories, however, neither of those are wise recommendations. “As a personal fitness trainer, I’m very weary of active people — especially those who work out regularly – skipping meals so frequently,” says Sassos. “If you’re fasting or restricting calories, you may not have enough fuel in the engine to power through your workout, which can lead to you feeling faint or even passing out. And more importantly, it’s important to eat a balance of protein and carbohydrates post-workout to help repair muscle tissue. If you work out in the morning and don’t start your feeding window until later in the day, this can have a severely negative impact on your exercise recovery and won’t optimize your athletic performance.”

The Bottom Line on the Warrior Diet:

The original Warrior Diet’s emphasis on whole, unprocessed foods is good advice, but all in all, the best healthy eating plan is one that works with your lifestyle and that you can sustain in the long-term says Sassos. It’s also one that is easy to stick with, and simple to incorporate into your life.

“If you find yourself falling into a binge/restrict cycle and a negative relationship with food and your body, it’s time to consciously unsubscribe from this type of diet mentality,” says Sassos. “Healthy eating should be about abundance and all of the amazing nutritious foods you’re adding into your diet, as opposed to taking away and restricting yourself. And your body needs time to digest food and absorb nutrients, so cramming everything into a short feeding window may take a toll. Remember: There is no ‘one size fits all’ approach to nutrition — everyone’s body is different and unique. The Warrior Diet is certainly not for women who are pregnant or trying to get pregnant, people with a history of disordered eating, children, or people with a history of diabetes or hypoglycemia (low blood sugar).”

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