High-intensity interval training (HIIT) may be the most effective form of exercise for reducing body fat while preserving muscle mass in older adults, according to new research led by academics at the University of the Sunshine Coast. While a range of exercise intensities were shown to promote some fat loss, HIIT stood out for its ability to protect lean muscle, a key factor in healthy ageing.
The study found that high-, moderate- and low-intensity exercise programmes all resulted in modest reductions in body fat. However, only HIIT allowed participants to lose fat without a corresponding loss of lean muscle. Lead author and exercise physiologist Dr Grace Rose said this distinction was necessary, as muscle preservation plays a central role in maintaining strength, mobility and independence later in life.
Researchers examined how different exercise intensities influenced body composition in healthy older adults. Moderate-intensity training successfully reduced fat mass but was also associated with a slight decline in lean muscle. In contrast, participants undertaking HIIT were able to achieve fat loss while maintaining muscle, suggesting that exercise intensity may be a critical factor when designing training programmes for ageing populations.
Both high- and moderate-intensity exercise were also found to improve fat distribution around the abdomen, an area closely linked with metabolic and cardiovascular disease risk. The effects of low-intensity exercise were less conclusive, and the research team noted that further analysis is required to fully understand how gentler forms of exercise influence body composition in older adults.
Dr Rose said the findings were particularly significant because changes in body composition are implicated in the progression of many chronic diseases associated with ageing. The study involved more than 120 healthy participants from the Greater Brisbane region, who completed three supervised gym-based exercise sessions per week over six months. Participants had an average age of 72 and a mean body mass index of 26 kg/m², which is considered normal for adults aged over 65.
Co-author Mia Schaumberg welcomed the publication of the research in the journal Maturitas, produced in collaboration with UniSC’s Healthy Ageing Research Cluster and the University of Queensland. She explained that HIIT in the study involved repeated short bursts of very demanding exercise, where breathing was heavy and conversation difficult, alternated with easier recovery periods. This higher level of muscular stress, she said, likely sends a stronger signal to the body to retain muscle tissue, making HIIT a promising strategy for healthy ageing.
More information: Grace Rose et al, Exercise intensity influences body composition: a 6-month comparison of high-intensity interval, moderate- and low-intensity training among healthy older adults, Maturitas. DOI: 10.1016/j.maturitas.2025.108763
Journal information: Maturitas Provided by University of the Sunshine Coast
