By peoplestaff225
Updated July 30, 2014 02:41 PM

Harley Pasternak is a celebrity trainer and nutrition expert who has worked with stars from Halle Berry and Lady Gaga to Robert Pattinson and Robert Downey Jr. He’s also a New York Times best-selling author, with titles including The Body Reset Diet and The 5-Factor Diet. Tweet him @harleypasternak.

Can you lose 11 pounds in 4 days? Yes. Is it a good idea? No way. Recently, a study published in the Scandinavian Journal of Medicine & Science in Sports reported on a group of 15 healthy, but overweight, men who subjected themselves to an extreme weight-loss regimen.

For 4 days, they consumed only 360 daily calories in either a high protein drink or a sugary drink. The guys started the day with a 45-minute upper body cardio workout, followed by an 8-hour outdoor group walk. Each hour they could take a 10-minute break and consume an unlimited amount of a low-cal sports drink.

The results? Each participant lost about 11 pounds, half of it body fat and half muscle mass, regardless of whether he’d had the protein drink or the sugary drink. Aside from a few achy joints and blistered feet, none felt any ill effects. Nor did they experience extreme hunger. Better yet, a month later, the men had shed on average another 2 pounds of fat. A year later, they were still down 5 pounds, mostly in body fat.

Am I recommending you try this program yourself? Not in a million years! But it does suggest that just because you lose weight quickly doesn’t mean you can’t keep it off. It all depends on whether or not you change your habits. In this case, the guys made those changes stick.

This is hardly the first study to find that the more pounds lost quickly, the more likely that weight loss can be maintained. In other studies, being physically active, eating breakfast, eating on schedule and making lifestyle changes, along with a number of psychological motivators, were also crucial to success.

In a more recent study, women were put on programs designed to achieve fast, moderate, or slow weight loss. The groups predictably lost the most, the middle amount, and least weight, respectively. And at 6 and 18 months later, the women who lost weight quickly were almost 5 times as likely to have lost 10 percent of their original weight and and keep it off than women in the slow group.

What’s my read on these results? Successful long-term weight loss is all about permanently replacing unproductive habits with positive habits. How about the ASAP factor? I see my clients regularly lose 5 pounds in 5 days. And no, it’s not anywhere near as grueling as walking for 8 hours and drinking meals with a straw! Instead, I ask them to simply follow my moderate diet plan, engage in a few minutes of vigorous resistance exercise, walk at least 10,000 daily steps, get enough sleep and disconnect from their electronic devices for 1 hour a day. With the motivation fueled by their initial success and by adopting these habits as their daily routine, they go on to achieve their weight loss goals.

Like the men in the study, my clients ate less and moved more. They changed their lifestyle, but without any blisters or achy joints!