A University of the Sunshine Coast study of 120+ adults averaging age 72 found that high-intensity interval training three times weekly for six months was the only exercise type to reduce body fat while preserving lean muscle mass. Moderate and low-intensity workouts also produced some fat loss, but moderate exercise caused a small decline in muscle. HIIT — short bursts of very hard effort alternated with recovery periods — appears to stress muscles enough to trigger a strong signal to retain tissue. Researchers say the findings are especially relevant for older adults, since body composition changes are closely linked to chronic disease risk and overall healthspan.
