A new study from the German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE) and Charité – Universitätsmedizin Berlin shows that intermittent fasting (time-restricted eating) with an unchanged calorie intake does not lead to measurable improvements in metabolic or cardiovascular parameters while shifting the body's internal clocks. The findings of this study were published in the journal Science Translational Medicine (STM).

The scientists conducted a randomized crossover design involving a total of 31 women with overweight or obesity. Over two weeks each, the participants consumed their usual meals either early, between 8 a.m. and 4 p.m.(eTRE), or late, between 1 p.m. and 9 p.m. (lTRE). The calorie and nutrient composition remained nearly identical (isocaloric).

During four visits, blood samples were taken from participants in the laboratory. Scientists also conducted an oral glucose tolerance test to analyze carbohydrate and fat metabolism. Unlike previous studies, the new research found no clinically significant changes in insulin sensitivity, blood sugar levels, blood fat content, or inflammation markers with intermittent fasting.

Researchers added that cardiovascular health markers did not improve significantly.

“Our results suggest that the health benefits observed in earlier studies were likely due to unintended calorie reduction, rather than the shortened eating period itself,” explained study co-author, Prof. Olga Ramich. “Those who want to lose weight or improve their metabolism should pay attention not only to the clock, but also to their energy balance.”