Eating Just One Meal a Day: Benefits, Side Effects?

I’ve got into the habit of eating just one meal a day.

As this is an unusual habit, I’ve done some in-depth research on the subject: is there any reason to believe that it could be bad for your health? Or on the contrary, that there are benefits, for health or weight loss?

My answers, with arguments!

♻️ Last update: March 15, 2025.
👩‍⚖️ Declaration of financial interests: none directly related to the subject. My complete declaration of financial interests is available in the legal notice section.
Written by Nelly Darbois, physiotherapist and scientific editor

Where does this tendency to eat just one meal a day come from?

In France alone, dozens of people Google every day for information on the benefits and risks of eating just one meal a day.

What makes me say that this is a “trend” is that this phenomenon is still only recently described in the scientific literature.

It is often associated with a more general type of diet known as intermittent fasting, which consists of alternating periods of fasting (when no calories are consumed) with periods of normal eating.

For example:

• eat 1 day out of 2, fast the other;
• Do not eat during a set period of time each day, for example between 8 p.m. on the previous day and 12 a.m. on the following day;
• the “one meal a day” or OMAD diet, also known as 23:1 becauseyou fast for 23 hours and take in all your calories in a one-hour period.

Do water and beverages count?

When we speak of a single meal a day, we mean meal by food intake, intake of solid food.

In general, people drink water, tea, herbal tea or coffee for the rest of the day.

❌ But not drinks like fruit juices, sodas or alcohol, which contain more calories.

❌What are the theoretical risks of eating just one meal a day?

Based on what we know about how the human body works, here are the potential risks of eating 1 meal rather than 3 to 4 meals a day.

• Long-termnutritional deficiency can cause fatigue, weakening of the immune system, muscle loss and brittle bones. Due to the difficulty of consuming all the necessary vitamins, minerals and macronutrients (proteins, lipids, carbohydrates) in a single meal – this risk can be avoided by controlling your diet.
• Digestive or sleep disorders due to eating a lot at once.
• Energy fluctuations (fatigue, loss of concentration, irritability, dizziness, etc.), due to long periods without calorie intake.
• Risk ofhyperphagia or dietary imbalance, even weight gain: extreme hunger accumulated during the day can lead to overconsumption of high-calorie, fatty or sweet foods.
• Reduced physical performance.
• Stress, anxiety, frustration, eating disorders, due to the pressure of “having” to eat only once.

All of these risks may be greater for more “fragile” people: pregnant women, breast-feeding mothers, children, teenagers, the elderly, or those suffering from chronic illnesses (diabetes, heart disease, etc.).

✅What are the potential benefits of eating all at once?

Now, let’s look at the potential benefits of eating just one meal a day, versus eating 3 or 4.

• Saves time: it takes less time to prepare (and think about) a single meal than several!
• Improved brain performance and even mood: starving your body puts you in a state of alertness that keeps you focused on your environment.
• Weight loss : eating only one meal can lead to eating less in quantity (although you can also compensate and “binge”).

Are there any scientific studies on the subject, and what do they say?

Although there are a few scientific studies on intermittent fasting, they are :

• in small numbers ;
• not very good quality;
• and above all, they don’t focus on eating just one meal a day, but on different types of intermittent fasting, including this one.

But let’s take a look at what we can learn from the most relevant studies.

To sum up in one sentence for those in a hurry: there’s nothing to suggest that eating one meal a day when you have no particular illness is dangerous for your long-term health. On the other hand, it’s not certain that it will help you lose or stabilize your weight over the long term.

In a synthesis (James 2024) including 12 studies on the effect of intermittent fasting on health (but not specifically eating only one meal a day), the research team concludes that this type of diet would be rather beneficial to improve :

• weight loss,
• blood lipid levels (linked to risk of atherosclerosis, hypertension and heart disease),
• glucose metabolism and insulin sensitivity (in relation to diabetes).

And would tend to reduce oxidative stress and inflammation.

This is seen mainly in blood tests, but not directly on people’s health.

In another synthesis of studies including more than 1,000 people practicing intermittent fasting (Elsworth 2023), the conclusions were as follows:

Intermittent fasting does not appear to reduce hunger, the feeling of satiety, the desire to eat or the planned quantities of food consumed, compared with conventional diets.

Is it better to eat your only meal in the morning, at noon or in the evening?

There’s already little data to say whether eating once a day is a safe practice. And even less to determine the best time.

Because of hormonal fluctuations, we generally have more appetite in the evening. That’s why, as far as I know, most people who eat once a day do so in the evening.

What do I do with just one meal a day?

Now that I’ve set out some facts about this way of eating, I’ll give you my own experience, as this often makes things more concrete.

At the age of 34, I had often not eaten between my last evening meal and the next day’s lunch.

I used to skip breakfast because I wasn’t particularly hungry at that time of day. I preferred to save myself for the other meals, except in special cases such as breakfast with the family.

And as time went by, I didn’t feel particularly hungry or hungry to eat at certain lunches either. Especially when I’m without my children (which doesn’t happen very often – only 2 lunches a week, and when they go on vacation to their grandparents’).

So I’ve got into the habit of skipping lunch as well as breakfast several times a week. In this case, I usually eat in 2 stages, a sort of mini-eating snack in the late afternoon, mostly fruit and vegetables, and a very large evening meal, which is when I really always feel like eating well.

This type of diet has had no impact on my weight gain or loss. On the other hand, I really do feel more alert during the day without eating, as well as saving a considerable amount of time.

I don’t do it every day, however, because meals with family and friends are always a great time to share.

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That’s all I wanted to say on the subject! Any questions or comments? See you in comments!