HIIT Helps Older Adults Lose Fat and Keep Muscle, University Study Finds
- High-intensity interval training reduces body fat while preserving lean muscle in older adults, according to a six-month trial published in the journal Maturitas.
- The study assigned 123 healthy older adults from the Greater Brisbane region to supervised gym sessions three times a week for six months.
- However, moderate training caused a small decline in lean muscle alongside fat loss.
High-intensity interval training reduces body fat while preserving lean muscle in older adults, according to a six-month trial published in the journal Maturitas. Researchers at the University of the Sunshine Coast evaluated 123 healthy participants with an average age of 72 to determine how different exercise intensities affect body composition. While low, medium, and high-intensity workouts all produced modest fat loss, only the high-intensity interval training retained lean tissue. The findings provide new data on how workout intensity shapes physical health in adults over 65.
Three Workout Intensities Compared Across Six Months
The study assigned 123 healthy older adults from the Greater Brisbane region to supervised gym sessions three times a week for six months. Each session lasted 45 minutes, with participants divided into high-intensity intervals, moderate-intensity exercise, and a low-intensity comparison group. Researchers measured body composition at the start of the study, at three months, and at six months using a specialized scanning technique that tracks fat and lean tissue.
However, moderate training caused a small decline in lean muscle alongside fat loss. Participants performing high-intensity interval training reduced their fat mass without experiencing that same drop in lean tissue.
We found that high, medium and low intensity exercises all led to modest fat loss but only HIIT retained lean muscle.
Dr. Grace Rose, University of the Sunshine Coast
Workouts Reduce Visceral Fat While Preserving Lean Tissue
Beyond overall fat mass, the trial tracked visceral adipose tissue, which accumulates deep inside the abdomen around internal organs like the liver and intestines. Both high- and moderate-intensity workouts improved the composition of weight carried around the middle. Excess visceral fat is linked to insulin resistance, cardiovascular disease, and other metabolic issues.
Preserving lean tissue remains a priority as people age, since strong muscles support physical independence, balance, and everyday tasks like climbing stairs. While the scans measured lean tissue rather than direct muscle strength, the training method provided a stronger stimulus for the body to maintain its tissue.
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.
Mia Schaumberg, University of the Sunshine Coast
Broader Research Context on Aging and Fitness
Subsequent studies published in 2026 explore how workout intensity applies to different settings and populations. An eight-week trial published in Medicine & Science in Sports & Exercise found that 20 older adults utilizing home-based, non-weight-bearing arm and leg machines lost an average of 1.4 kilograms of fat mass. Another 16-week randomized trial published in The Journals of Gerontology, Series A compared interval training with continuous moderate exercise in older adults living with HIV, noting that adding resistance training helped both groups reduce fat and increase lean mass.
A broader scientific review published in August 2026 in the Journal of Clinical Medicine examined 25 reports covering 2,818 participants and found consistent cardiovascular improvements from interval training. The Centers for Disease Control and Prevention recommends that adults over 65 combine aerobic exercise, muscle strengthening, and balance activities, advising inactive individuals or those with medical conditions to build up their fitness gradually.