Various diets claim to help you lose weight and improve your health. One of the more popular diet trends at the moment is eating only one meal per day, also known as OMAD. But is it healthy?

Q: Can I eat just once a day, preferably by 5 p.m.? How would it affect my overall health in the long term?

Many people swear by OMAD as an effective way to improve their health and lose weight. However, health practitioners tend to advise against OMAD because it’s extreme and likely to do more harm than good.

OMAD can be considered a type of intermittent fasting method because it restricts your total daily calorie intake to a single meal, while you fast for the rest of the day. This should create a calorie deficit, which is necessary to lose weight — while offering health benefits from fasting.

However, compared with other intermittent fasting methods, eating only one meal per day is extreme and can have undesirable and potentially dangerous side effects.

For starters, it’s difficult to fit your daily nutrient intake into a single meal. Not consuming an adequate amount of nutrients regularly can put you at risk of a nutritional deficiency, which has serious health risks.

Additionally, only consuming one meal per day can raise your risk of hypoglycemia (low blood sugar), especially among older adults and people with diabetes (1).

Plus, only eating one meal per day isn’t ideal for people with a history of an eating disorder. In fact, research suggests that only eating once per day may increase the risk of disordered eating habits like binge eating (2, 3).

Lastly, eating one meal per day may cause other side effects, including (4):

  • extreme hunger
  • fatigue
  • irritability
  • difficulty concentrating
  • nausea
  • dizziness
  • constipation

Notably, one study found that only eating one meal per day increased blood pressure and total and LDL (bad) cholesterol levels, compared with eating normally and following less extreme fasting methods (5).

If you’re looking to lose weight and improve your health, there are better and more sustainable diets, including a low carb, whole food diet, the Mediterranean diet, or a plant-based diet. If you’re looking to add fasting into your routine, try the 16/8 intermittent fasting method or 5:2 diet instead.