Eating only once a day has become popular for weight loss, but experts warn about its risks.
More and more people are adopting an extreme eating pattern: eating only once a day, concentrating their entire caloric intake in a single meal.
This habit, touted as a fast track to weight loss, improved energy, and a longer lifespan, has sparked the interest of those seeking effective methods to control their weight. However, specialists warn that this practice could have serious health consequences .
This type of diet involves fasting for approximately 23 hours, leaving a very limited window—usually 60 minutes—to consume all of the day’s nutrients. It’s an intensified form of intermittent fasting, a strategy often applied in more flexible versions such as the 16:8 schedule, where you can eat during eight hours of the day.
Does it work, and is it safe for your health? Although it seems simple—less planning, fewer meals, no constant calorie counting—science still doesn’t offer conclusive answers about its long-term effects.
What does the scientific evidence say?
So far, the available studies are limited, but they offer some clues. A study published under the title “Differential Effects of One Meal per Day in the Evening on Metabolic Health and Physical Performance in Lean Individuals” revealed that healthy people who ate just one meal a day for 11 days lost more weight and body fat than those who ate three times a day, despite consuming the same number of calories.
However, these same participants also reported increased hunger, fatigue, and difficulty maintaining the regimen, raising questions about its long-term viability.
Furthermore, the American Heart Association warns that reducing the eating window to less than eight hours could increase the risk of cardiovascular mortality, calling into question the safety of this type of extreme fasting.
The purported benefits include rapid weight loss, improved glucose control, and decreased inflammation, all effects observed in studies of prolonged fasting. However, experts agree: the quality of the evidence is still insufficient to recommend this practice as a general health strategy.
Possible risks and side effects
Limiting food consumption to a single meal a day makes it difficult to meet the body’s nutritional needs, which can lead to protein, vitamin, and mineral deficiencies, as well as causing symptoms such as dizziness, irritability, concentration problems, and fatigue.
From a psychological perspective, going so many hours without eating can increase the risk of binge eating, which can not only destabilize the metabolism but also cause digestive discomfort.
For people with conditions such as diabetes, chronic illness, a history of eating disorders, pregnancy, or those who engage in strenuous physical activity, this strategy can be especially risky and should be avoided without medical supervision.
Is it worth a try?
The current medical consensus is clear: eating only once a day is neither sustainable nor safe for most people. Although it may produce temporary weight loss results, the metabolic and nutritional risks are significant.
For those who wish to incorporate fasting into their lifestyle, specialists recommend more balanced methods, such as fasting for 12 to 16 hours, allowing adequate time to meet the body’s energy needs without compromising health.