Body fat percentage refers to the ratio of fat mass and lean mass throughout a person’s body. It’s an indicator of health and in the case of sports, often of performance. For both athletes and the general population, understanding what constitutes a healthy body fat percentage and why this metric matters is helpful for achieving a balanced and healthy lifestyle.

So, here’s your complete guide to body fat percentage, including how it can affect your running performance and the pros and cons of this measurement.

So, what is a healthy body fat percentage? A lot of factors go into the answer to that question, including age, sex, race, sport, and life stages, like pregnancy.

According to Dr Farhan Malik,a board-certified sports medicine physician, the general population should aim for body fat percentages between 14 to 31 percent for women and 6 to 25 percent for men. Athletes, however, often have different and/or narrower ranges due to the demands of their sports.

The American College of Sports Medicine (ACSM) provides helpful charts for understanding body fat percentages and how they relate to health and performance.

Healthy Body Fat Percentage, According to the ACSM*

Men

• Age 20-29: 7.9–18.6%
• Age 30-39: 12.5–21.6%
• Age 40-49: 15.0–23.5%
• Age 50-59: 17.0–24.9%
• Age 60-69: 18.1–25.6%
• Age 70-79: 17.5–25.2%

Women

• Age 20-29: 15.2–23.5%
• Age 30-39: 15.5–24.8%
• Age 40-49: 16.8–27.4%
• Age 50-59: 19.1–30.0%
• Age 60-69: 20.1–30.8%
• Age 70-79: 18.8–30.0%

*This data combines the ranges for “excellent,” “good,” and “fair” according to the ACSM chart.

“Endurance athletes like marathon runners and cyclists tend to have very low body fat levels, often in the range of 6 to 13 percent for men and 14 to 20 percent for women,” says Malik. “This helps maximise aerobic capacity and power-to-weight ratio. Having minimal excess fat is advantageous for sports requiring sustained effort over long distances or times.”

Now that doesn’t mean you have to keep close tabs on your body fat percentage in order to see success in a sport like running. The ranges above simply represent averages across large populations of athletes — they’re not a requirement in any way, and the “ideal” body fat percentage for an athlete in any sport doesn’t exist. What’s best is highly individual.

Malik also points out that strength and power athletes like football players and weightlifters often aim for higher body fat levels of 15 to 25 percent for men and 25 to 35 percent for women. Again, nothing about these ranges are required — they’re just averages.

“Some additional fat cover can protect against injuries during collisions [in these sports], allow for greater caloric surpluses to build muscle mass, and provide energy reserves for short explosive bursts,” he explains. “Sports with weight classes may also influence target body composition.”

The takeaway is that body fat targets depend heavily on the demands of the sport, Malik says, so “the focus should be on optimising health and performance rather than sticking to generalised body fat percentage guidelines.”

Worth noting, the ACSM recommends a fat mass no lower than 3 percent for men and no lower than 10 percent for women, because both health and performance are likely to be negatively impacted at those points. Women may experience amenorrhea (absence of menstruation) and risk losing crucial bone mineral density, which can lead to osteoporosis. Men may experience low testosterone, which can lead to a number of symptoms and health issues.

Regardless of sex, too-low body fat can cause symptoms like constantly feeling cold, fatigued, and weak; a weakened immune system, leading to frequent illness; and brittle hair, skin, and nails.

“The key is to stay within a healthy range based on age, sex, and fitness goals,” says Malik. “The body requires some fat for vital physiological processes. However, excessive or insufficient amounts of body fat can increase the risk of chronic disease.”

To be more specific, too much body fat, particularly visceral fat around the abdomen, is associated with increased risks of chronic diseases like heart disease, diabetes, and certain cancers, Malik says. On the other hand, extremely low body fat can disrupt hormone levels, weaken immunity, and reduce muscle mass, also leading to poor health outcomes.

Muscle mass supports metabolic health in a number of ways, including increasing energy expenditure and improving insulin sensitivity. Muscle mass is also important for healthy aging.

Meanwhile, fat serves as an energy reserve and aids in hormone production, insulation, and organ protection.

Maintaining an optimal balance is especially important as we age, considering muscle loss and fat gain tend to accelerate over time. This shift can lead to decreased strength, mobility issues, and increased risks of metabolic diseases.

While any type of exercise can help you lose body fat if you’re in a calorie deficit (eating fewer calories than you burn), some research suggests that aerobic training leads to more weight and fat loss over long-term periods. But, resistance training is the most effective way to build muscle, and helps reduce lean mass loss — that is, helps maintain your muscle mass — during weight loss periods. That combination of fat loss and muscle gain is what leads to an improved body composition.

Malik emphasises that “certain types of exercises, such as high-intensity interval training (HIIT), are especially beneficial due to their ability to burn calories quickly and increase metabolic rate even after the workout ends.”

The big thing about HIIT is that it seems to produce equal or better results in less time, compared to steady-state exercise. This is an important factor in the busy lives people have today. A randomised controlled trial published in 2021 found HIIT to be as effective for fat loss as moderate-intensity steady-state exercise (such as going for a 45-minute run), but with shorter workout duration (the HIIT sessions lasted about 35 minutes).

While scientific literature can guide us to the most efficacious forms of exercise for losing body fat, the most critical factor long-term is adherence. You may have heard this before, but the best type of exercise is the type you can stick to forever.

Mohr stresses the importance of making sure the calorie deficit is “not so severe that you have low energy and aren’t getting enough nutrition.”

Lifestyle factors are also important, according to Mohr. Sleep, stress management, and hydration play a big part in managing body fat. Poor sleep, for example, can lead to hormonal imbalances that make it harder to lose fat, while chronic stress can increase levels of cortisol, a potential factor in fat storage.

• Body fat scales, which are often found in gyms
• Skinfold calipers, which you can buy and learn to use online
• More precise methods of measurement, like DEXA scans or BOD POD testing

Each tool has its own limitations, Mohr says, whether that is accuracy, cost, or availability. When in doubt, a mirror, progress photos, and/or a journal can be a cost-effective way to monitor progress.

The important thing is to measure under the same conditions consistently and to measure over longer periods of time, like weeks or months, to see true trends rather than daily fluctuations. Try to measure at the same time of day — ideally, before you’ve eaten breakfast or had any water — and in the same or similar clothing.

There’s one big caveat to consider here: Taking bodyweight and body fat percentage on a regular basis isn’t the right approach for everyone. Individuals with a history of eating disorders or (even an undiagnosed) complicated relationship with food and/or exercise should take caution with frequent weigh-ins. In fact, some research has suggested that frequently checking one’s weight, body shape, or fat mass can result in significant emotional distress among athletes. If you find yourself becoming obsessed with the numbers or images, stop tracking.

Final Thoughts
Understanding what a healthy body fat percentage is — and why it matters — can guide you toward better health and performance in your sport. While the ideal range varies depending on factors like age, sex, and athletic goals, the principles remain consistent with general health guidelines: prioritise a balanced approach to fat loss and muscle gain, stay active, eat a diet rich in nutrients, and manage stress and sleep.

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