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A study led by the research team from the Department of Sports Science and Physical Education at The Chinese University of Hong Kong (CUHK) has revealled that combining flexible time-restricted eating with aerobic exercise significantly reduces fat mass in middle-aged women with overweight or obesity. On average, the proportion of fat mass reduction is more than double that achieved by diet or exercise alone, and the combined intervention also provides more effective improvements in insulin sensitivity and other metabolic indicators. This study demonstrates that intermittent fasting such as the 16:8 diet does not necessarily rely on a fixed daily eating window. As long as the principle of timing is observed and paired with exercise, both convenience and health benefits can be achieved. The findings have been published in the international journal Nature Communications.

Obesity is a major health challenge for middle-aged women. Due to ageing and physiological changes during menopause, women are prone to increased body fat, especially abdominal fat accumulation, and declining metabolic function, which elevates the risk of developing type 2 diabetes and cardiovascular diseases. Lifestyle intervention is key to weight management, but conventional calorie-restriction diets are often difficult to sustain long-term. In recent years, intermittent fasting has gained widespread attention for its simplicity, with time-restricted eating being a popular approach. However, previous studies often adopted a fixed eating window, which lacks flexibility in real-life settings and fails to reflect the diversity of daily life. Led by Professor Stephen Wong Heung-sang and PhD student Dai Zihan from the Department of Sports Science and Physical Education at CUHK, this study aimed to explore flexible time-restricted eating, allowing participants to set a daily eight-hour eating window, to be concluded by 8:00 p.m., and investigating its practical health benefits and feasibility in a free-living context when combined with aerobic exercise.

The research team conducted a 12-week randomised controlled trial from September 2023 to July 2024. They recruited 104 overweight or obese women aged 40 to 60 and randomly assigned them to four groups: a flexible time-restricted eating group, an aerobic exercise group, a combined intervention group (combined flexible time-restricted eating group and aerobic exercise) and a control group. The results showed that the combined intervention group achieved the most significant fat loss. After 12 weeks, they experienced an average reduction of 2.7 kg in fat mass (-10.2%), which was significantly greater than the reductions in the eating-only group (-4.6%) and the exercise-only group (-3.5%). Moreover, the study further confirmed that the combined group achieved greater improvements in body weight, body fat percentage, waist circumference and metabolic health markers such as insulin sensitivity (HOMA-IR, QUICKI), compared to the single-intervention groups (please refer to appendix).

Notably, adherence rates were high across all intervention groups (83-87%) and no serious adverse events were reported, indicating that combining flexible time-restricted eating with exercise is both safe and feasible in a real-life settings. Professor Wong noted that the combination would be more effective in reducing fat accumulation than either strategy alone. He added that allowing personalisation of the eating window would enhance the practicality of the regimen, providing an effective, easy-to-implement, sustainable lifestyle management strategy for middle-aged women facing weight management challenges.

Professor Wong is the study’s corresponding author and Dai Zihan is its first author. Co-authors include Professor Masashi Miyashita from Waseda University in Japan and Professor Eric Poon Tsz-chun, Professor Tian Xiaoyu, Professor Angus Yu Pak-hung and Professor Cindy Sit Hui-ping from CUHK.

The full research article is available at https://doi.org/10.1038/s41467-025-65678-z