What Is the Mono Diet?

"Mono diet" (also known as the monotrophic diet) has been one of the most searched diets on the internet in recent years. If you've heard of it, you've probably read the claims that it can lead to quick and easy weight loss. But the claims are not rooted in any science, and there are plenty of science-backed reasons to avoid trying a mono diet.

The mono diet entered the mainstream in 2016 when the magician Penn Jillette published the book, "Presto! How I Made Over 100 Pounds Disappear and Other Magical Tales." In it, Jillette credits a two-week mono diet with kickstarting his weight loss journey. The idea was to interrupt his regular eating pattern with a restrictive mono diet and then restart with a healthier diet, though the book is more humorous than it is a reliable resource. He even mentions in interviews that you don't need all the nutrients within 2 weeks, which is a false statement.

For 14 days, Jillette claims he ate nothing but potatoes (about five a day). Later, he began eating fruits, vegetables, and some whole grains. Once Jillette's mono diet made headlines, people who were looking to lose weight wondered if they should try this method, too.

But according to health and nutrition experts, there is no healthy version of a mono diet, despite what you may have read in the media. Your body needs a variety of nutrient-rich foods to function properly. Learn more about the risks associated with mono diets and why health experts agree that they are neither safe nor sustainable methods for weight loss.

What Can You Eat?

When you follow a mono diet, you eat only one food for several days or weeks. There are different variations of the mono diet, including a banana mono diet, an egg mono diet, a potato mono diet, and even a chocolate mono diet. There are no official or formal rules for how to follow this type of diet; it's open to interpretation.

What You Need to Know

Some people follow a mono diet by sticking with one group of foods such as fruit, vegetables, or meats. Others do mono meals, eating a single food for each meal, but eventually rotating that single food with others. Either way, meal planning is simple (in fact, it's almost unnecessary), since mono diets call for eating just one food or a very limited number of foods. In spite of and in part due to their simplicity, mono diets are not recommended for weight loss.

Pros and Cons

Is the Mono Diet a Healthy Choice for You?

The U.S. Department of Agriculture 2020–2025 Dietary Guidelines for Americans recommends consuming a variety of nutrient-dense foods including all types of vegetables, legumes, fruits, whole grains, dairy products or lactose-free substitutes, fortified soy products, lean protein, eggs, seafood, nuts, and other healthy fats like oils. Federal guidelines also advise limiting foods and beverages with higher amounts of added sugar, saturated fat, and sodium, and limiting the consumption of alcohol.

Clearly, mono diets fall short of these standards, especially when the singular food of choice is high in saturated fat, sugars, or refined carbohydrates and no other foods are eaten. Even if you were to eat three different mono meals a day, you would only get three different kinds of food for that day.

The USDA suggests a daily intake of approximately 1,500 calories a day for weight loss and 2,000 calories a day for weight management, but these numbers can vary based on age, weight, sex, genetic background, ethnicity, and activity level. It's not feasible to get a suitable number of calories from a single food, and this unconventional eating plan does not meet expert guidelines for healthy nutrition.

For example, Jillette's all-potato diet meant he probably consumed only about 750 calories a day, which is far fewer than what's required for men of his height (6 feet, 6 inches), even with the goal of weight loss. At a minimum, you need 1,200 calories per day to stay healthy. Calculate your own daily calorie needs for weight loss with this tool.

Health Benefits

Short-Term Weight Loss

When you eat only one food—even if that food is high-calorie—your caloric intake plummets over the course of a day. You will probably experience quick water loss and decreased bloating as a result. You are also likely to lose muscle mass over time. However, these "weight loss" results are likely to be short-lived, and any weight lost is likely to be regained.

Additionally, proponents of mono diets say these programs help to curb cravings. But in reality, avoiding certain foods can lead to a desire for the foods you can't have. This can rebound and lead to overeating.

Health Risks

Dangerously Restrictive

There are significant health consequences when you don't eat a variety of foods to provide your body with enough nutrients. Severe restrictions leading to rapid weight loss can also cause gallstones, electrolyte imbalances, constipation, headaches, irritability, menstrual irregularities, hair loss, and dehydration. Experts caution that those following a mono diet will likely experience fatigue, decreased metabolism, malnourishment, and muscle loss.

Nutrition researchers also warn that cutting back on calories can lead to compensatory behaviors, such as binge eating. This may occur especially when the person has low self-efficacy to maintain the psychology associated with dietary restrictions.

In 5 studies involving overweight and obese study participants, severe calorie restriction helped curb binge eating especially when weight loss was greater than 10%. If weight loss was less than 10%, it decreased binge-eating episodes in the short-term, but binge-eating returned in the long-term. The best outcomes occurred when participants were medically supervised and were receiving supplements to meet their nutritional needs.

Doesn't Promote Healthy Habits

To both lose weight and maintain a healthy weight, it's important to determine the best foods for your nutritional needs and to learn how to manage portions. You also need to exercise, get enough sleep, and manage stress. And you need support, whether it's from peers or professionals. A mono diet does not support these healthy, sustainable habits.

Could Lead to Body Image Issues

Managing hunger can be challenging. In fact, studies have shown that severely restricting your caloric intake increases stress hampering weight loss goals. In a 2016 study, researchers found that young college students are likely to experience compensatory behavior and that women are likely to experience dissatisfaction with their bodies as a result of severe calorie restriction associated with some diets.

A Word From Verywell

Due to their restrictive nature and inadequate vital nutrients, mono diets are not recommended by health experts. While it may seem like a quick and simple approach to weight loss, denying your body of important macro and micronutrients is dangerous and can lead to a variety of health problems.

Setting up a healthy weight loss program may take time and effort, but it is a worthwhile investment. You're much more likely to feel better, enjoy a boost of body confidence, and have healthier outcomes when you follow a nutritious diet and exercise plan to lose weight.

Remember, following a long-term or short-term diet may not be necessary for you and many diets out there simply don’t work, especially long-term. While we do not endorse fad diet trends or unsustainable weight loss methods, we present the facts so you can make an informed decision that works best for your nutritional needs, genetic blueprint, budget, and goals.

If your goal is weight loss, remember that losing weight isn’t necessarily the same as being your healthiest self, and there are many other ways to pursue health. Exercise, sleep, stress management, mindful eating, and other healthful lifestyle factors also play a major role in your overall health. The best diet is always the one that is balanced and fits your lifestyle.