Eating one meal a day can work for some people but may cause nutrient gaps, low energy, and overeating. It is not suited to everyone, so check with a doctor.
Possible benefits
Some studies on time restricted eating show weight loss in the short term.
Risks
- Nutrient gaps.
- Low energy and mood swings.
- Overeating at the meal.
- Slower metabolism for some.
- Risk of disordered eating.
Research
A 2020 study in the journal Hypertension linked one meal a day to higher blood pressure.
Who should avoid
Pregnant women, people with diabetes, children and anyone with an eating disorder.
Check
Talk to a doctor first.
What it is
Eating one meal a day (OMAD) is a form of intermittent fasting with a 23 hour fast and a one hour eating window.
Possible benefits
Some people find it simple for weight control. Studies of time restricted eating show modest weight loss, mainly from reduced calorie intake.
Research
A 2022 study from the National Institute on Aging in Cell Metabolism found that men and women eating one meal a day had decreased body weight but higher fasting glucose, higher blood pressure and greater morning cortisol levels than those eating three meals. Another NIH study in 2007 reported similar findings with higher cholesterol. A 2020 review found no clear advantage of intermittent fasting over conventional calorie restriction for weight loss.
Risks
- Difficulty meeting nutrient needs, in particular protein, fiber, vitamins and minerals, in one sitting.
- Hunger, fatigue, headaches, irritability, poor concentration and trouble sleeping.
- Overeating or binge eating at the meal.
- Higher risk of gallstones with rapid weight loss.
- Loss of muscle mass.
- Low blood sugar in people with diabetes taking medication.
Who should avoid it
Pregnant or breastfeeding women, children and teens, people with a history of eating disorders, diabetes (without medical supervision), underweight individuals, and anyone on medication that must be taken with food.
If you try it
Choose nutrient dense foods, drink water, get enough protein (1.2 to 1.6 grams per kilogram), include vegetables and healthy fats, and consider a less extreme method like a 16:8 pattern. Talk to your doctor.
Balanced approach
The Dietary Guidelines for Americans emphasize regular, balanced eating, with an overall pattern rich in vegetables, fruits, whole grains and lean protein.
Research on one meal a day
Eating one meal a day is a form of intermittent fasting. A controlled study by Stote and colleagues, published in 2007 in the American Journal of Clinical Nutrition, found that healthy adults eating one meal a day for 8 weeks had higher blood pressure and higher total and LDL cholesterol than when eating three meals, though they also lost a little fat. A 2022 trial in the New England Journal of Medicine found that time restricted eating produced weight loss similar to simple calorie counting. A 2024 conference abstract from the American Heart Association linked 8 hour eating windows with higher cardiovascular death risk in an observational study, but the finding was preliminary.
Who should avoid it and how to try safely
People with diabetes on insulin or sulfonylureas, pregnant or breastfeeding women, children and teens, people with a history of eating disorders and those with certain medical conditions should avoid it. Fitting enough protein, fiber, vitamins and minerals into one sitting is difficult, and some people experience fatigue, headaches, irritability or binge eating. A moderate approach is eating balanced meals within a 10 to 12 hour window. Talk to a doctor or dietitian before major changes.
Based on data from the American Journal of Clinical Nutrition and the New England Journal of Medicine
