The mono diet is a simple eating pattern that involves eating just one food item or food group for all meals throughout the day.

Proponents claim that the mono diet can increase weight loss quickly, without requiring you to track your intake or plan your meals in advance.

However, others note that the diet is not based on any evidence and can be overly restrictive, unsustainable, and unhealthy.

This article reviews the benefits and side effects of the mono diet to determine whether you should give it a try.

  • Overall score: 0.58
  • Weight loss: 0.5
  • Healthy eating: 0
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  • Whole body health: 0.5
  • Nutrition quality: 1
  • Evidence-based: 1

BOTTOM LINE: Although some claim that the mono diet can promote rapid weight loss, it’s not backed by research and unhealthy, unsustainable, and likely to lead to nutritional deficiencies in the long term.

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Also known as the monotrophic diet, the mono diet is an eating pattern that involves eating just one food item or food group for several days or weeks at a time.

It made headlines in 2016 when magician Penn Jillette mentioned following the mono diet to kick-start his weight loss in his book “Presto! How I Made Over 100 Pounds Disappear and Other Magical Tales.”

Since then, it has become a fast favorite among dieters seeking a simple way to boost weight loss without all of the rules and restrictions of other eating plans.

Several variations of the mono diet have also risen in popularity, including the milk diet, carnivore diet, fruitarian diet, and egg diet.


The mono diet involves eating just one food item or food group for several days or weeks at a time.

There are several types of mono diets and many ways to follow the plan.

One of the most common variations involves eating a single food item for each meal, such as potatoes, apples, or eggs.

Others stick to ingredients within a specific food group instead, such as meat, fruits, or vegetables.

You can also choose to switch between “mono meals” by eating a different food item at each meal.

Although there are no specific guidelines regarding how long you should follow the diet, most use it to ramp up weight loss by following it for just 1 or 2 weeks at a time.

Other foods can then be gradually reintroduced, such as soups, salads, and smoothies, before transitioning into a healthy and balanced diet.

However, some people may also choose to follow certain variations of the diet, such as the fruitarian diet or carnivore diet, for longer periods of time without reintroducing other foods into their diet.


On the mono diet, you should stick to just one food item or food group for each meal. Most people follow the mono diet for a few weeks before transitioning back to a healthy, balanced diet.

Almost any food can be included on the mono diet.

Here are a few of the most common examples of foods included on the mono diet:

  • potatoes
  • apples
  • eggs
  • milk
  • bananas
  • pears
  • watermelon
  • chocolate
  • grapefruit

Some variations of the mono diet also involve consuming just one food group throughout the day.

Here are some examples of food groups that can fit into a mono diet:

  • meats
  • fruits
  • vegetables
  • legumes

Nearly any food can be consumed on the mono diet, including potatoes, apples, eggs, and bananas. Some variations involve sticking to one specific food group, such as meats, fruits, vegetables, or legumes.

For most people, eating just one food per day will likely lead to decreased intake and weight loss.

However, whether you’ll lose weight on the mono diet depends on which foods you’re consuming and how much of them.

For example, if you’re only eating low calorie foods like vegetables, you’re likely to consume fewer calories — or even too few calories — throughout the day, which may lead to weight loss.

Conversely, if you’re eating large amounts of high calorie foods like chocolate, you may gain weight on the diet (1, 2).

Keep in mind that there’s no research on whether mono diets can be effective for weight loss.

Additionally, mono diets are typically not sustainable in the long term and may be followed by weight regain once a normal diet is resumed.


Depending on what foods you’re consuming and in what amounts, mono diets may lead to short-term weight loss. However, mono diets may also lead to weight regain once a normal diet is resumed.

One of the biggest benefits of the mono diet is its simplicity.

Unlike other fad diets, there are no complicated guidelines to follow. However, this is because mono diets are extremely restrictive and cut out most healthy foods. Just because a diet is simple, doesn’t mean it’s healthy.

It also doesn’t require dieters to track nutrients, count calories, or measure portion sizes, which could be appealing to some people.

It may also be effective for short-term weight loss, depending on which foods you consume and in what amounts. Still, know that this has nothing to do with the mono diet in particular.

The weight loss achieved on a mono diet is simply due to the calorie restriction that comes from cutting out most foods. Any extreme diet is likely to lead to short-term weight loss. However, this weight loss is rarely maintained in the long term.

Although it’s unsustainable and may be difficult to follow for long periods of time, some people use it to kick-start weight loss before transitioning to other dietary patterns.


The mono diet is very simple and doesn’t have any complex rules or regulations. It may also increase short-term weight loss, depending on what you eat.

The mono diet may be associated with several potential downsides and side effects.

Increases risk of nutritional deficiencies

The mono diet involves eating just one food item or food group for several days or weeks at a time.

Even nutrient-rich foods may be lacking in specific vitamins or minerals, which can make it difficult to ensure that you’re getting all of the nutrients that your body needs.

It can also increase your risk of nutritional deficiencies, especially if you’re following the diet for prolonged periods of time.

For example, if you’re only eating bananas, it may be challenging to get enough protein, healthy fats, iron, calcium, and vitamins A and B12 in your diet (3).

Similarly, meat, fish, and poultry are lacking in important nutrients like vitamin C, fiber, and antioxidants (4, 5, 6).

A deficiency in these nutrients can lead to issues like impaired immune function, anemia, digestive conditions, bone loss, and chronic disease (7, 8, 9, 10, 11).

Promotes unhealthy eating habits

The mono diet promotes unhealthy and unsustainable eating habits by encouraging the consumption of a single food item or food group.

It also requires dieters to cut out all other foods, including healthy ingredients that are rich in essential vitamins and minerals.

Additionally, the diet doesn’t provide any recommendations for physical activity, which is essential for supporting both weight management and overall health (12, 13).

What’s more, some research suggests that following fad diets and yo-yo dieting may be associated with a higher risk of eating disorders and conditions like obesity and type 2 diabetes, among others (14).

Combining a well-rounded diet with a healthy lifestyle and regular physical activity is a better strategy to support weight loss, your overall health, and a healthy relationship with food.

Restrictive and unsustainable

The mono diet is one of the most restrictive fad diets, eliminating almost all foods and food groups apart from those that are included in your diet.

Because it’s nearly impossible to eat enough calories and meet your micronutrient needs through just one food or food group, the mono diet may leave you feeling tired, hungry, and weak (15, 16).

Consuming too few calories can also slow your metabolism and lead to muscle loss, making it more difficult to lose weight in the long run (17, 18).

Furthermore, some studies have found that restricting calories too much could even lead to bone loss and negatively affect fertility in women (19, 20, 21).

Additionally, it can be very difficult to eat at restaurants or enjoy certain social situations while following the mono diet.

Therefore, it may be challenging to follow the diet for more than a few days or weeks at a time.


The mono diet promotes unhealthy eating habits and may increase your risk of nutritional deficiencies. It’s also highly restrictive and unsustainable in the long run.

The mono diet is an eating plan that involves eating just one food item or food group for several days or weeks.

Although it may lead to short-term weight loss, it’s also unsustainable, promotes unhealthy eating habits, and can increase your risk of nutritional deficiencies.

For this reason, following a healthy, balanced diet that includes a variety of nutritious ingredients is a better option to promote long-term weight loss and overall health.