A new study from the University of the Sunshine Coast (UniSC) suggests that high intensity interval training (HIIT) might be the only exercise that lets older adults lose fat without also losing muscle. Because apparently, you can't have nice things with moderate jogging.

Researchers compared different exercise intensities in healthy older adults and found that all levels of exercise produced some fat loss. But 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.

The study explored how exercise intensity affects body composition, which is a fancy way of saying what your body is made of. As people age, this becomes increasingly important because changes in body composition are linked to chronic diseases. Moderate intensity exercise, it turns out, has a downside: "While moderate training reduced fat mass, it also caused a small decline in lean muscle," Dr. Rose said. So you might lose some flab, but you'll also lose some of that precious muscle you've been hoarding.

The study included more than 120 healthy older adults from the Greater Brisbane region, who completed three gym based exercise sessions each week over six months. On average, participants were 72 years old and had an average body mass index of 26 kg/m², which is considered normal for adults over 65.

The findings were published in the journal Maturitas and involved researchers from UniSC's Healthy Ageing Research Cluster and The University of Queensland. UniSC Associate Professor Mia Schaumberg noted that the research arrives just in time for New Year's resolutions. "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.

For those unfamiliar, HIIT involves repeated short intervals of very demanding exercise followed by easier recovery periods - essentially, sprinting until you can't talk, then shuffling until you can do it again. "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," Dr. Rose explained. So the secret to staying buff in your golden years is to make your muscles think they're in a crisis. Got it.