Yet another weight loss plan?

A new study, published in the Scandinavian Journal of Medicine & Science in Sports, suggests that minimal calories and maximal exercise can significantly reduce body fat in just four days — and the loss lasts for months. The catch, of course, is that those four days are pretty grueling.

Researchers in Spain and Sweden had 15 healthy but overweight Swedish men restrict their calories to about 360 a day, a reduction of approximately 1,800 calories. What calories they did ingest came in liquid form: Some men drank mostly sugary carbohydrates, others a high-protein drink. The men also exercised — a lot. Their days began with 45 minutes of cranking an arm-pedaling machine for an upper-body workout. Then, as a group, the men strolled for eight hours across the Swedish countryside, with only a 10-minute break every hour. They were allowed as much of a low-calorie, sports-type beverage as they wanted during their walks.

After four days, the men had each lost almost 11 pounds, with nearly half of that coming from body fat; the rest of the loss came primarily from muscle mass.

But given the doleful statistics on weight loss — most people regain everything they lose dieting and more — these results are startling. They also, at the moment, are inexplicable. “The only explanation we can offer” for the sustained loss, the researchers say, is that the men were inspired by their hypercompressed success to change their lifestyles. The men moved more and ate less than before.