If obese people eat only during a certain window each day without counting calories, they naturally eat about 425 fewer calories a day over a year, which helps them lose weight—even though no one told them to eat less.

If you eat only between noon and 8 p.m. without counting calories, you’ll lose about the same amount of weight over a year as someone who cuts their daily calories by 25%—the difference is so small it could just be due to chance.

If obese people only eat between noon and 8 p.m. every day—without counting calories—they tend to lose about 4.6 kg (over 10 pounds) in a year, just by changing when they eat, and not by eating less.

If you're overweight and eat only between 8 a.m. and 4 p.m. for a year, you’ll lose about 8 kg — but if you just eat fewer calories without worrying about when you eat, you’ll lose about 6.3 kg. The difference is so small that it doesn’t really matter which method you pick — cutting calories is what matters most.

People who are obese and eat only during an 8-hour window each day—without counting calories—stick to this routine 87% of the time for a full year, which suggests it’s a practical way to manage weight long-term.

If you're an adult with obesity and you eat only during certain hours of the day for a year, it won't make you more likely to have bad side effects than if you just eat fewer calories every day.