Intermittent fasting plus exercise boosts fat loss and fitness in 12-week obesity trial
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A research team led by the Joint University Institute for Sport and Health (iMUDS) at the University of Granada, in collaboration with the Granada Institute for Biomedical Research and the Biomedical Research Network Center, has studied the effects of combining intermittent fasting and supervised exercise in people with obesity as part of the TEMPUS project.
The study, published in the journal Nature Communications, shows that combining intermittent fasting and supervised exercise promotes greater weight and body fat loss, in addition to improving cardiorespiratory fitness in people with obesity, although no greater reduction in accumulated liver fat was detected compared with standard care.
Four groups tested over 12 weeks
The trial included 187 adults with obesity, approximately half of whom were women. The participants were randomly assigned to four groups: standard care, intermittent fasting, supervised exercise and fasting combined with exercise. For 12 weeks, all groups received education on the Mediterranean diet and physical activity.
In addition, those who practiced intermittent fasting concentrated their meals within an eight-hour window each day. The exercise groups followed a supervised program that combined strength training and high-intensity aerobic exercise.
Weight loss outpaces liver fat changes
The primary objective was to determine whether these strategies led to a greater reduction in liver fat—measured by MRI—and an improvement in cardiovascular health. The results showed that liver fat decreased in all four groups. However, no statistically significant differences were found between the interventions and standard care, nor among the three interventions themselves.
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, on average, about 2.2 kilograms (4.9 pounds) greater than in the standard-care group. The combination of fasting and exercise also resulted in greater body fat loss than standard care and exercise alone. Meanwhile, the two groups that exercised improved their cardiorespiratory fitness, a marker of cardiovascular health.
Antonio Clavero Jimeno, co-lead author of the study and a predoctoral researcher at the University of Granada (UGR), notes that "these results allow us to assess the effects of the interventions beyond weight, also taking into account changes in liver fat deposits, as well as total body fat and physical fitness."
Liver fat signals and long-term limits
The study, which is part of Clavero Jimeno's doctoral dissertation, also examined the response to the interventions in men and women. Among men, the combination of fasting and exercise produced a greater reduction in liver fat than standard care. This additional difference was not observed among women.
Alba Camacho Cardeñosa, co-lead author of the study and a postdoctoral researcher at ibs.GRANADA, notes, however, that "for now, these analyses alone do not allow us to conclude that the intervention works differently depending on sex."
Furthermore, among participants with fatty liver at the start of the study, approximately 30% of those who combined fasting and exercise no longer met the criteria used to diagnose this condition, compared with 6.5% in the standard-of-care group.
One year after completing the program, no differences were found between the groups in changes in liver fat. Furthermore, the differences in weight and body composition observed at the end of the 12 weeks were no longer detectable. These results suggest that it is necessary to analyze longer-term interventions, especially in people with high levels of liver fat, as well as strategies to help maintain the benefits.
Publication details
Antonio Clavero-Jimeno et al., Effects of time-restricted eating and supervised exercise on intrahepatic fat and cardiometabolic health in adults with obesity: the TEMPUS randomized controlled trial, Nature Communications (2026). DOI: 10.1038/s41467-026-78625-3
Journal information: Nature Communications
Key medical concepts
Intermittent FastingWeight LossCardiorespiratory Fitness
Clinical categories
Weight managementEndocrinologyFitness & Physical activityHealthy livingDigestive health Provided by University of Granada Who's behind this story?
Swati Mestri
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