If you're an adult with obesity, eating only during a certain window each day for a year won't help you lose more waist size, weight, or fat—or improve your blood pressure and metabolism—any better than just eating fewer calories every day.

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.

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.

When obese women only eat during a short window each day (without counting calories), they lose less weight and gain more belly fat than when they eat fewer calories overall.

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 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.