A new randomized trial suggests that combining intermittent fasting with supervised exercise may deliver greater short-term weight and body fat loss in adults with obesity than standard care, although the approach did not reduce liver fat more than usual care over 12 weeks.
The study, led by researchers from the Joint University Institute for Sport and Health at the University of Granada and published in Nature Communications, followed 187 obese adults, about half of them women, who were assigned to standard care, intermittent fasting, supervised exercise, or the combined intervention. All participants received advice on the Mediterranean diet and physical activity, while those in the fasting groups limited eating to an eight-hour window each day.
Weight and body fat improved, but liver fat results were mixed
According to the research team, participants who fasted, with or without exercise, lost more weight than those who exercised only or received standard care. In both fasting groups, weight loss was about 2.2 kilograms greater than in the standard-care group. The combination of fasting and exercise also produced greater body fat loss than standard care and exercise alone, while the exercise groups improved cardiorespiratory fitness.
However, the primary goal of the study was to determine whether the strategies could reduce liver fat measured by MRI and improve cardiovascular health. Liver fat decreased in all four groups, but there were no statistically significant differences between the interventions and standard care, or among the three active interventions themselves.
Possible implications for obesity management
The researchers said the findings suggest the benefits of the intervention extend beyond weight alone, even if the effect on liver fat was not superior to standard care in the short term. Among participants with fatty liver at the start of the study, around 30% of those who combined fasting and exercise no longer met the criteria for the condition, compared with 6.5% in the standard-care group.
One year after the program ended, however, the differences in liver fat, weight and body composition were no longer detectable, underscoring the challenge of maintaining benefits over time. The authors said longer-term studies are needed to better understand how to sustain results, especially in people with higher levels of liver fat.
The study adds to ongoing UK and international interest in obesity care, where clinicians continue to look for practical strategies that can be combined with dietary guidance, physical activity and medication where needed. For readers seeking the original report, the study summary is available at News Medical.
While the trial was not a direct comparison with drug-based treatment, it reinforces a familiar message in obesity medicine: short-term progress can be meaningful, but long-term support is often essential if weight-loss gains are to be preserved.
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