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High intensity interval training (HIIT) may be the optimal exercise for reducing body fat while maintaining muscle mass in older adults, according to new research led by UniSC academics.

“We found that high, medium and low intensity exercises all led to modest fat loss but only HIIT retained lean muscle,” said lead author and exercise physiologist Dr Grace Rose of the University of the Sunshine Coast.

The study examined how the intensity of different exercises could influence body composition in healthy older adults.

“While moderate training reduced fat mass, it also caused a small decline in lean muscle,” she said.

“Both high and moderate intensities improved the composition of weight carried around the middle. Further analysis is needed of the low intensity results.”

Dr Rose said the findings were particularly useful because body composition was implicated in the progression of many chronic diseases as people aged.

More than 120 healthy older adults from the Greater Brisbane region participated in the study, completing three exercise sessions a week in the gym for six months. 

Their average age was 72 years old and average body mass index was 26kg/m², categorised as normal for people aged over 65.

UniSC Associate Professor of Physiology and co-author Mia Schaumberg welcomed the timing of the paper published in the journal Maturitas, with collaborators including UniSC’s Healthy Ageing Research Cluster and The University of Queensland.

“With the festive season now behind most of us and New Year’s resolutions in full swing, this research can help inform people’s plans for healthy ageing in 2026,” she said.

“High intensity training in this study involved repeated short bursts, or intervals, of very hard exercise – where breathing is heavy and conversation is difficult – alternated with easier recovery periods.

“HIIT likely works better because it puts more stress on the muscles, giving the body a stronger signal to keep muscle tissue rather than lose it.”