[Spot! Health] Is Weight Control Possible with Exercise Alone?

As the autumn season of abundant harvest returns, more people are starting to exercise to control their weight. However, many are unsure about the appropriate intensity and duration of exercise needed for effective weight management. Obesity can lead to various diseases such as hypertension and dyslipidemia, so continuous management and effort are necessary for weight control.

Is it possible to control weight through exercise alone? Professor Son Ki-young of the Department of Family Medicine at Seoul Asan Medical Center said, "Reducing calorie intake is the key to weight management." One kilogram of body fat is roughly equivalent to about 7,700 kcal. Simply put, if the calories burned exceed the calories consumed by 7,700 kcal, it is expected that 1 kg of body fat will be lost. Since one bowl of rice typically contains about 300 kcal, reducing rice intake by half a bowl per meal also reduces side dishes, resulting in a daily calorie reduction of about 450 kcal. If calorie expenditure remains the same, one can expect to lose about 1 kg of body fat every 2 to 3 weeks. A person weighing around 70 kg burns only about 140 kcal per day by doing moderate exercise for 30 minutes. Therefore, trying to lose weight through exercise alone while maintaining the same food intake is very difficult.

The generally recommended amount of exercise is 150 minutes of moderate-intensity exercise or 75 minutes of high-intensity exercise per week. If moderate exercise is assigned 1 point per minute and high-intensity exercise 2 points per minute, achieving 150 points or more per week meets the recommended exercise amount. However, this recommendation is for preventing cardiovascular diseases and not specifically for weight loss. In other words, more exercise than these numbers is needed to reduce weight.

Professor Son explained, "For aerobic exercise, moderate intensity means being slightly out of breath but still able to talk with a companion, though singing would be difficult. High intensity means being so out of breath that talking with a companion is impossible." When defining exercise intensity objectively, heart rate is used. Moderate intensity is generally 64?76% of maximum heart rate, and high intensity is above 77%. Maximum heart rate is calculated as '220 minus your age.' For example, a 40-year-old doing moderate exercise would need to maintain a heart rate of at least (220-40) × 0.64 = 115 beats per minute to be exercising at moderate intensity or higher.

If you can calculate how many calories to reduce from intake and how many to burn through exercise, you can manage your weight more systematically. The unit MET (Metabolic Equivalent of Task) is used to calculate calorie expenditure according to exercise intensity.

Moderate exercise usually ranges from 3 to 6 METs, and high-intensity exercise is 6 METs or higher. For convenience, assuming moderate intensity as 4 METs and high intensity as 8 METs, a 70 kg person exercising 120 minutes of moderate intensity and 30 minutes of high intensity per week would burn about 840 kcal through exercise in a week. Assuming calorie intake remains constant, it would take at least two and a half months to lose 1 kg of body fat.

Exercising intensely over the weekend can also be effective. Just as sweating on a treadmill for 30 minutes five times a week is beneficial, vigorously doing the butterfly stroke for 75 minutes at the swimming pool on weekends is also effective. However, caution is needed as high-intensity exercise in a short period increases the risk of injury.

This content was produced with the assistance of AI translation services.