Only one workout helped older adults lose fat without losing muscle

The research compared different exercise intensities in healthy older adults and found that all levels of exercise produced some fat loss. However, only HIIT helped participants preserve lean muscle.

“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.

Exercise Intensity and Body Composition

The study explored how exercise intensity affects body composition, an important factor in overall health as people age.

According to Dr. Rose, moderate intensity exercise also helped reduce body fat, but it came with a downside.

“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 noted that the findings are particularly important because changes in body composition are linked to the development and progression of many chronic diseases later in life.

Six Months of Supervised Exercise

The study included more than 120 healthy older adults from the Greater Brisbane region. Participants completed three gym based exercise sessions each week over a six month period.

On average, participants were 72 years old and had an average body mass index of 26kg/m², which is considered normal for adults over age 65.

The findings were published in the journal Maturitas. The project involved researchers from UniSC’s Healthy Ageing Research Cluster as well as The University of Queensland.

Why HIIT May Protect Muscle

UniSC Associate Professor of Physiology and study co-author Mia Schaumberg said the research arrives at a useful time, as many people focus on health and fitness goals at the start of a new year.

“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 aging in 2026,” she said.

In the study, HIIT consisted of repeated short intervals of very demanding exercise followed by easier recovery periods.

“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.”