When losing weight, the body doesn't only lose fat but also some muscle mass (lean body mass). Research indicates that between 20 and 40 percent of lost weight comes from lean body mass. With aging, preserving muscle becomes more important for maintaining strength, mobility, and independence.

A recent study suggests that high-intensity interval training (HIIT) may help older adults preserve muscle mass while reducing body fat.

HIIT Exercises May Help Preserve Muscle

Researchers followed 123 healthy adults with an average age of 72, who participated in supervised training sessions three times a week for six months.

Participants were divided into three groups:

- High-intensity interval training (HIIT).

- Continuous moderate-intensity aerobic exercise.

- Low-intensity exercise.

Results showed that both the HIIT and moderate-intensity groups lost fat and reduced visceral fat (belly fat). However, only the HIIT group maintained muscle mass while decreasing body fat percentage, whereas the other group lost a small amount of muscle along with fat.

The researchers noted that the differences between groups were limited and may not have a tangible impact on health or physical performance in daily life. Therefore, the study does not prove that HIIT is far superior to others, but it may offer a small additional benefit for improving body composition in healthy older adults.

Why Might These Exercises Help?

HIIT exercises alternate between short bursts of intense physical activity and recovery periods.

Lakshmi Kumar, an exercise physiologist, said that high effort prompts the body to recruit more fast-twitch muscle fibers compared to continuous moderate-intensity exercise.

She added that these fibers are responsible for generating strength and power, and stimulating them may help preserve muscle mass even on a low-calorie diet.

HIIT also increases calorie burning during and after exercise through what is known as excess post-exercise oxygen consumption (EPOC), but the contribution of this phenomenon to total calories burned remains limited.

Kumar explained that these exercises also improve the muscles' ability to produce energy and enhance the heart's efficiency in pumping blood and delivering oxygen to muscles.

Not the Only Solution

People gradually lose muscle mass with age due to a condition known as sarcopenia, which can impair strength, balance, mobility, and overall health. Preserving muscle helps support independence, strengthen bones, and improve blood sugar regulation.

But experts warn against relying solely on HIIT.

Kumar said that resistance training remains the most important factor for preserving muscle mass during weight loss, along with adequate protein intake, good sleep, and allowing sufficient recovery between intense workouts.

She added that it is best to combine HIIT with moderate-intensity aerobic exercises such as brisk walking, cycling, or light jogging, as these build aerobic fitness while HIIT improves high-intensity performance.

She emphasized that the optimal program for long-term health combines regular physical activity, resistance training, moderate-intensity aerobic exercise, HIIT sessions, along with proper nutrition and adequate recovery.

Is It Suitable for Everyone?

Experts warn that HIIT is not suitable for everyone, especially:

- People who have not exercised for a long time.

- Those recovering from injuries.

- Individuals with untreated heart conditions.

Kumar advises building fitness gradually through walking, cycling, or jogging before starting HIIT, and those with heart disease or uncontrolled metabolic disorders should consult a doctor before engaging in HIIT.

The study concludes that the best exercise program is one that can be adhered to long-term, rather than relying on a single type of exercise.