As people get older, losing fat without also losing muscle gets harder. A six-month study of healthy adults in their 70s suggests the intensity of exercise may matter: in this trial, only the hardest workouts trimmed fat while leaving lean mass intact.
Who Took Part and What They Did
Researchers at the University of the Sunshine Coast in Australia, working with the University of Queensland, recruited 123 healthy older adults from the Brisbane area. Their average age was 72, and their average body mass index was about 26, which the team described as normal for people over 65. The results were published in the journal Maturitas.
Participants were split into three groups. Each did three supervised gym sessions a week, 45 minutes at a time, for six months:
- High-intensity interval training (HIIT): short bursts of very hard effort, the kind where talking is difficult, alternated with easier recovery periods.
- Moderate-intensity training: steady exercise at a comfortable but challenging pace.
- Low-intensity training: a gentler comparison group.
Body composition was scanned at the start, at three months and at six months to estimate fat and lean tissue.
What the Researchers Found
- All three groups lost a modest amount of fat; the high- and moderate-intensity groups lost more than the low-intensity group.
- The moderate group lost a small amount of lean mass along with the fat.
- The HIIT group lost fat without that decline in lean mass.
- Both the HIIT and moderate groups improved visceral fat, the deep abdominal fat linked to chronic disease. The low-intensity results still need more analysis.
Co-author Mia Schaumberg suggested HIIT may protect muscle because it puts more stress on it, signaling the body to hold on to that tissue. That’s a proposed explanation, not something the study tested.
Why focus on body composition rather than weight? Lead author Grace Rose, an exercise physiologist, pointed out that the balance of fat and lean tissue is tied to how many chronic diseases progress with age. Losing weight that includes muscle can leave older adults weaker, so a workout that removes fat while sparing lean tissue is the more useful result. The university first announced the findings in January, and they drew fresh attention this month.
How It Fits With Other Research
The broader evidence is more mixed. A systematic review published in August in the Journal of Clinical Medicine pooled 25 reports covering about 2,818 participants. Its most consistent finding was better cardiorespiratory fitness, and it didn’t find HIIT reliably better than moderate exercise overall.
A 16-week trial in older adults with HIV, in The Journals of Gerontology, found that both HIIT and moderate exercise, each paired with resistance training, led to fat loss and lean mass gains, with no significant difference between them. And a small eight-week trial of 20 adults ages 61 to 74 doing home-based HIIT on a seated arm-and-leg machine reported about 1.4 kg (3 pounds) of fat loss, 96% adherence and no exercise-related injuries.
The Catch
- The scans measured lean mass, which includes water and other tissue, not muscle strength. Keeping lean mass isn’t the same as getting stronger.
- The researchers themselves noted the differences were relatively small and not clearly meaningful in clinical terms once measurement uncertainty is considered.
- Participants were healthy and closely supervised. Results may not apply to people with heart conditions, joint problems or limited mobility.
- The published summaries don’t give exact numbers for how much fat or lean mass each group gained or lost.
What This Means for You
The study doesn’t mean everyone over 65 should start sprinting. It does suggest that, for healthy older adults, adding some harder effort may be worth considering, and that easy-only exercise may leave some benefits on the table.
The CDC’s baseline for adults 65 and older is a good anchor: at least 150 minutes a week of moderate activity (or 75 minutes of vigorous activity), muscle-strengthening work on at least two days that hits all the major muscle groups, plus activities that improve balance. Strength training is its own part of that advice, and our look at how much strength training you really need covers the details.
If you’re inactive or have a medical condition, talk to your doctor first and build up gradually.
More on Contoh
- How Much Strength Training Do You Really Need? What the Research Says
- Taking the Stairs Is a Small Habit With a Big Research Footprint
- Do You Really Need 10,000 Steps a Day? What the Research Says
Sources
- ScienceDaily: Only one workout helped older adults lose fat and keep muscle
- University of the Sunshine Coast: Research finds exercise type to target body fat in seniors
- Medical News Today: HIIT may help older adults lose fat while preserving muscle
- CDC: Physical activity guidelines for older adults
This article is for general information, not medical advice.