Scientists tested intermittent fasting without eating less and found no metabolic benefit

"A new study from the German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE) and Charité -- Universitätsmedizin Berlin challenges a widely held belief about intermittent fasting. The research shows that time-restricted eating does not lead to measurable improvements in metabolic or cardiovascular health when calorie intake remains unchanged. However, the timing of meals did affect the body's internal clocks. These findings come from the ChronoFast study led by Prof. Olga Ramich and were published in Science Translational Medicine."

"Time-restricted eating (TRE) is a form of intermittent fasting that limits daily food intake to a window of no more than ten hours, followed by a fasting period of at least 14 hours. The approach has become popular as a simple strategy to support weight management and metabolic health. Animal studies show that TRE can protect rodents from diet-related obesity and metabolic problems. In humans, earlier studies have reported benefits such as improved insulin sensitivity, healthier blood sugar and cholesterol levels, and modest reductions in body weight and body fat. As a result, TRE has been widely viewed as a promising tool for preventing insulin resistance and diabetes."

Time-restricted eating (TRE) limits daily intake to an eating window of up to ten hours followed by at least 14 hours fasting. TRE without calorie reduction did not produce measurable improvements in metabolic or cardiovascular markers, including insulin sensitivity, blood glucose, cholesterol, body weight, or body fat when calorie intake remained unchanged. Meal timing consistently shifted internal circadian clocks and altered sleep patterns. Animal experiments showed metabolic protection in rodents, and some human trials reported modest metabolic and weight benefits, indicating that calorie reduction likely underlies observed health improvements.

Read at ScienceDaily