Celebrities have been known to follow all sorts of weird dietary trends over the years. And one of the latest celebrity trends is the “one meal a day” (or “OMAD”) diet.
Many OMAD proponents claim that it helps them better control their weight and stay in shape.
OMAD is essentially a more extreme version of other types of lean diets such as intermittent fasting and timed eating. The main difference is that instead of only fasting on certain days or eating only during a specific time window, people who follow OMAD consume all of their daily calories in one big meal.
But while OMAD proponents say the diet improves many aspects of health, we actually know very little about the effects of just one meal a day on the body, let alone whether it’s safe.
Fasting and health
Evidence supporting the use of OMAD is limited. There are very few studies that have analyzed OMAD itself, and most have been done in animals.
Thus, most statements about OMAD are anecdotal. Or they are based on the assumption that if other forms of fasting can benefit health, so can OMAD.
Some evidence suggests that a form of intermittent fasting known as the “5:2 diet” (where a person typically eats five days a week and then 800 calories or less two days a week) may help people better manage their weight. However, it is no better than other dietary approaches.
Research has also shown that time-restricted eating (where you eat all your calories for the day for a set period of time) can help people manage their weight better. It has other health benefits as well, such as lowering blood pressure.
One review study also found that several different types of fasting (including intermittent fasting and two-day fasting) can improve some aspects of metabolism.
These include increasing blood sugar and cholesterol levels, reducing inflammation, and helping people improve their appetite. This, in turn, may help reduce the risk of obesity, type 2 diabetes, and cardiovascular disease.
Only one meal
To date, one study has examined the effects of OMAD on humans. In this study, participants were given the same number of calories every day for the duration of the study. For half of the study, participants consumed those calories in one meal before moving on to consuming their daily calories divided into three meals per day.
Each meal plan was followed for only 11 days—not much at all. One meal was between 17:00 and 19:00. Only 11 participants completed the study.
When participants ate only one meal a day, they saw greater reductions in body weight and fat mass. However, participants also experienced greater decreases in muscle mass and bone density when eating only one meal a day. This can lead to decreased muscle function and an increased risk of bone fractures if the diet is followed for a longer period.
Animal studies examining the effects of OMAD have produced conflicting results: Studies have shown that mice that ate one large meal a day actually gained more weight compared to those that ate multiple meals.
While these results may indicate that OMAD may be beneficial for some aspects of health, there is still a lot we don’t know about it.
It will be important for future research to explore the effect of OMAD on more participants and other groups of people (because only lean young people were included in this study). It will also be important that studies examine the effects of OMAD over a longer period of time, and that these tests be conducted under real-world conditions.
It would also be interesting to see if meal timing can further improve outcomes and if the nutritional profile of a meal makes a difference.
If someone only eats once a day, it will be very difficult for them to meet all of their nutritional needs, especially energy, protein, fiber, and essential vitamins and minerals. Lack of these important nutrients can lead to muscle loss, risk of constipation, and poor gut health.
And someone after Omad will have to make sure he’s getting a good serving of protein, plenty of vegetables, nuts and seeds, some fruit and whole grains in his single daily meal to meet those nutritional needs.
They will also need a good serving of dairy to make sure they meet their calcium and iodine needs, or supplements or substitutes if they are vegetarians.
We do not recommend this diet to children, any woman who is pregnant, hoping to become pregnant or breastfeeding, and certainly not to those at risk of developing an eating disorder.
It’s also important to note that while this diet may work for celebrities, they also have access to nutrition experts and high-quality diets and nutritional supplements when needed. And for most of us, this type of diet can be unsustainable and potentially harmful in the long run.
The report was prepared by Amanda Avery, Lecturer in Dietetics at the University of Nottingham.
Source: Science Alert
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