A new study published in Science Translational Medicine suggests that intermittent fasting may not improve metabolic health unless it is accompanied by caloric restriction.
The study included 31 women who were overweight or had obesity. The trial had a crossover design in which each participant completed two interventions, each of which lasted two weeks. The first intervention involved a time-restricted eating schedule from 8 a.m. to 4 p.m., while the section intervention involved a time-restricted eating schedule from 1 p.m. to 9 p.m. Each intervention had identical meals with the same caloric and nutritional content. Before, during, and after the interventions, blood samples and other health measurements were taken. The goal of the study was to see whether time-restricted eating could improve insulin sensitivity and other metabolic health markers, as well as whether the timing of the restricted eating window would impact results.
The results showed that there were no clinically meaningful changes in metabolic measures such as insulin sensitivity, blood sugar, or inflammatory markers before and after the two-week intervention windows. However, the circadian rhythms of the participants did change based on when their eating window occurred. The later eating window caused the internal clocks of the participants to shift back by about 40 minutes compared to the early eating window.
These results conflicted with several earlier findings, which had suggested that intermittent fasting may improve markers of metabolic health. However, the authors of this study noted that the positive results of earlier studies may have been caused by unintentional caloric restriction rather than intermittent fasting alone. For this reason, people who want to improve their metabolism and cardiometabolic health should pay particular attention to their overall calorie consumption rather than relying solely on intermittent fasting to improve their health.
Sources: Science Translational Medicine, Science Daily
