Society has an ongoing fascination with the constantly shifting trends in celebrity diets. The one meal a day (or OMAD) diet is one such trend, reportedly championed by the likes of Bruce Springsteen, Coldplay frontman Chris Martin, football pundit Gary Lineker and even Rishi Sunak, the prime minister. But does the science back up the claims?


OMAD is an extreme fasting diet. As the name suggests, it involves eating just one big meal a day, with fasting or very minimal eating in between. The key focus of this kind of diet is weight control and simplicity.

There are many celebrity anecdotes surrounding OMAD and from an evolutionary point of view, it can seem reasonable to suggest that human biology is better suited to less frequent meals. This theory is based on our ancestors often experiencing cycles of feasting and fasting rather than the relatively modern construct of three meals a day.

But while fasting itself isn’t new, the research on its health impacts is still in its infancy and there are very few studies on OMAD and the evidence supporting other more periodic types of fasting can’t necessarily be extrapolated into extreme fasting.

One trial exists on OMAD, where participants ate only one meal a day, or three meals per day, with their calorie intakes tailored to theoretically maintain their current weight.

When on one meal per day they reduced body weight and fat levels, and displayed features of “metabolic flexibility” (changes in measures of how fats and carbohydrates are metabolised). But participants also experienced a loss of muscle and bone mass. This highlights that a focus on weight loss alone can miss the potential downsides of this kind of diet.

Importantly, the results of this study can’t be applied to everyone. Only relatively healthy people were included and no one with obesity, cardiovascular disease, diabetes, mental disorders, eating disorders or other metabolic conditions was allowed to participate.

Furthermore, the trial was small and short, with just 11 participants following the diet for 11 days.

Read more:

What are the risks associated with the OMAD diet?

One of the claims made by supporters of OMAD and other fasting diets is that you can eat whatever you want for the one meal you are eating each day. But if all nutrients for good health are to be obtained in just one meal, it needs to be nutrient dense and balanced to ensure you get a sufficient intake of fibre, protein, vitamins and minerals.

More like this

Supplements may help avoid nutritional deficits but they lack the complexity of foods, which means other healthy essentials, such as bioactive compounds, may be missed. This means there may be longer-term consequences for bone, digestive and other elements of your health, despite the easy-to-measure and instantly gratifying weight loss.

Indeed, when meal frequency has been studied in larger groups (over 24,000 people) for longer periods (about 15 years), eating just one meal a day was linked to a higher risk of death from any cause, and from cardiovascular diseases.

Observational studies like this can’t show the cause of the relationship, but the results were found even when factors like age, gender, race, ethnicity, education, income, smoking, alcohol intake, physical activity, energy intake, food insecurity, snacking habits and health at the start of the study were taken into account.

Rishi Sunak
Prime minister Rishi Sunak reportedly follows the OMAD diet at least one day a week. © Getty

It’s also important to consider the other roles that food plays in our lives. Food is more than just calories and nutrition. It’s part of our culture, society, celebrations and enjoyment of life.

The social and emotional consequences of OMAD have not been documented but there is data showing that restrictive diets can have significant psychological consequences.

Reporting on celebrity trends is part of how pseudoscience and fake news spread in the health and beauty industry. There may be limited resources to fully fact-check the articles and few details mentioned of how stringently celebrities are truly following these diets. Plus, their true health, beyond their appearance, isn’t known.

Remember: any information is being shared selectively and facts can be omitted for the sake of the story. As long as stories on celebrity diets remain a good source of ‘clicks’, they’ll be fraught with clickbait – and extremes like OMAD give us just that.

The average person considering OMAD, or any other celebrity diet, does not have the same luxuries and supports that celebrities do: the nutritionists, the nannies and the other assorted assistants, for example.

So, we don’t all have the same capacity to deal with the potential side effects that come with extreme fasting, which can include nausea, dizziness, low energy, irritability and constipation. Celebrity lifestyles are enticing but this is precisely because they’re so unlike our own.

Celebrities give us many great things, like films, music, art and sports, but they’re not the most reliable source of nutrition information. Instead, official dietary guidelines, based on the complete body of nutrition science knowledge should be used for general advice, and qualified health professionals like dietitians should be consulted for your individual needs.

Read more:



Dr Emma Beckett is a food and nutrition scientist and registered nutritionist who works as a senior lecturer at the University of Newcastle, Australia and Nutrition Research Australia. Her research has been published in journals including Nature Communications and the American Journal Of Human Biology