The standard advice on losing weight is simply to eat less. The body’s fat stores are, in fact, surplus energy that a person has accumulated by eating too many calories.

“So basically it’s not wrong to eat less, but starving down the body’s metabolism won’t bring lasting results,” according to Ingo Froboese, a professor at the Health Centre of the German Sport University in Cologne.

“Although the body loses weight within a few days, most of it is water.” Muscle-building and endurance training are a better way to lose weight. As Mr. Froboese explained, when a person goes on a diet, the body draws on its energy reserves to sustain itself. If calorie intake is increased again, the body remembers the shortage it has just withstood and stores additional reserves for future shortages — “the yo-yo effect occurs,” he said.

“A negative energy balance is the key to losing weight,” Mr. Froboese remarked. In other words, more calories must be burned than are taken in. This can be achieved with muscle-building training.

“Since muscles consume energy, muscle-building training — and consequently a higher proportion of muscle in the body — is one of the building blocks for a lasting increase in energy turnover,” he said.

For a long-term reduction of body weight, low-intensity endurance training of 30 to 60 minutes — depending on the person’s level of conditioning — is the most effective form of activity.