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The one meal a day diet is a popular diet plan that claims to help people lose weight through intermittent fasting. When following this diet, a person only eats one meal a day, usually dinner, and does not consume any other calories during the day.

Although this diet plan may help people find a fast weight loss solution, the risks may outweigh the benefits.

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The one meal a day diet requires that a person only eat during 1 hour of a 24 hour day.

The one meal a day diet is a weight loss plan that requires a person to eat only one meal per day. This is a type of intermittent fasting that involves alternating between extended periods of not eating or drinking anything with calories and periods of eating.

The one meal a day diet utilizes a type of intermittent fasting referred to as 23:1, meaning a person spends 23 hours of the day fasting, leaving just 1 hour a day to eat, drink and consume calories.

In the one meal a day diet, most people choose to not eat or drink anything with calories during the day. They break their fast when they eat dinner, then resume fasting until the following evening.

What do you eat on the one meal a day diet?

There are several variations of the one meal a day diet. Some variations suggest eating healthful, nutrient-rich foods, but most versions of the diet allow people to eat anything they want during their single meal.

People who follow the one meal a day diet believe there are numerous benefits to eating this way, including rapid weight loss.

Other purported benefits include:

  • the diet is easy to follow because a person does not count calories
  • there are no "cheat days" because there are no foods considered off-limits

There have been several studies conducted on the effects of intermittent fasting. However, most of the studies have been carried out on men, so less is known about the effects of intermittent fasting on women.

Because of women's hormonal cycles, it is likely that the effects of intermittent fasting may be different in women. Women also have different nutritional requirements than men, including more iron, which may not be fulfilled while fasting.

The studies done on intermittent fasting show the following benefits:

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Eating only one meal a day may cause weakness, exhaustion, and inability to focus.

While some research supports the benefits of intermittent fasting and the one meal a day diet, an extreme diet plan comes with several risks.

The daily risks include:

  • becoming extremely hungry
  • shakiness
  • weakness
  • irritability
  • inability to concentrate
  • fatigue

There are also serious risks for people with underlying medical conditions. People with diabetes or low blood sugar, known as hypoglycemia, need to eat meals regularly throughout the day to avoid any serious side effects.

One study in published in JAMA involving 100 people found that intermittent fasting raised LDL cholesterol (bad cholesterol). Higher levels of LDL cholesterol are linked to increased rates of heart disease and stroke.

The same study also found that the participants following an intermittent fasting diet did not experience any more weight loss than those who simply reduced the number of calories they ate each day.

Finally, people following the one meal a day diet may have an increased risk of binge eating.

Binge eating is a disordered pattern of eating where a person eats unusually large amounts of food in a short period, even after they are full. Some people that follow the one meal a day diet may even develop binge eating disorder.

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Weight loss support groups and regular exercise are safer and more reliable methods for losing weight.

While the one meal a day diet may be appealing to people looking for quick weight loss solutions, there are other, less extreme ways to lose weight safely and healthily.

Anyone interested in losing weight should consider one of the following safer alternative ways to shed some pounds. These include:

  • Exercising regularly: People who want to lose weight should get at least 150 minutes of cardiovascular exercise, such as running or aerobics, each week.
  • Keeping a food diary: A person trying to lose weight can gain insight into their food intake by keeping a journal of food eaten and when. Food journals are available for purchase online.
  • Getting support: People who are trying to lose weight find support from loved ones or fellow dieters valuable.
  • Eating a balanced, nutritious diet: People looking to lose weight should eat enough fruits and vegetables and limit consumption of high-calorie junk food.
  • Talking to a doctor: A doctor can check for any underlying medical conditions, such as thyroid problems, that may be causing a person to hold on to unwanted weight.

The best weight loss solutions are sustainable, long-term changes to a person's diet and lifestyle.

The one meal a day diet is a weight loss plan based on the principle of eating only one meal a day and fasting for the rest of the time. Although this diet may help some people lose weight, other people may be frustrated by going for long periods of time without food.

The one meal a day diet is not the best choice for everyone, as some individuals may be more at risk for some adverse side effects.

While there are some research-backed benefits to intermittent fasting, more research needs to be done to verify if this diet is safe and effective for weight loss, particularly in women.

People who want to lose weight should start by making small, sustainable changes to their diet and lifestyle. It is best to consult a doctor or dietitian on how to safely lose weight, particularly if a person has any underlying medical conditions.