LOSING WEIGHT is never easy. But just imagine how much harder it would be if you were a chef. Food, and temptation, is all around you, all the time. And it's your job. They're paying you to taste, savor, sip, and taste some more.

Add in the long hours and limited down time, and it's easy to see why some chefs struggle with living a healthy lifestyle.

We asked three local chefs who are trying to change their eating habits, exercise habits and lifestyles to share their secrets to, so far, success.

_ Derek Davis, chef/owner, Derek's, Main Street, Manayunk. 6-feet 2 1/2 inches, 280 pounds.

"I'd come to work in the morning, and just start picking," said Davis. Davis found himself gaining weight over the past 10 years or so, but it wasn't until he packed 290 pounds that he finally said, "Basta!"

"I was also worried about my kids, and their weight and health. And I realized that I couldn't sit on my a-- and tell them to exercise if I didn't do it too."

Davis, 45, decided he needed professional help. He turned to a good friend, Lisa Hark, a registered dietician who happens to be a nutrition expert at the University of Pennsylvania and co-author of the book, Nutrition for Life (DK Adult, $30). Hark, who also hosted the TLC show "Honey We're Killing the Kids," agreed to help Davis change his ways.

"We approached it as a family project and involved the kids," said Davis.

Three months later, Davis has dropped 10 pounds and is exercising an average of three times a week. He's changed many of his eating habits, but in a way he can live with.

"I've tried to get Derek to focus on behavior modification, not a lot of don'ts," said Hark. "Chefs have definite challenges. They eat standing up all day - insidious calories they might not even be aware of. It's tough for them to find balance in their day because of the long hours they work. And they tend to eat late at night and go right to bed, which basically means whatever they eat turns to fat."

For the first time in years, Davis is eating breakfast, a critical part of jump-starting the body's metabolism. Although lactose intolerant as a kid, he's found that he can now enjoy whole grain cereal, fruit and skim milk to start the day.

"I've also cut back on the grazing, and I'm not drinking as much wine as I was. Instead of finishing a bottle of wine at dinner, we don't. Basically, it's not a diet - I'm trying to change the way I live. Mentally, I feel so much better."

Davis hopes to drop 70 more pounds, and he's in it for the long haul. "My wife Robyn really hung in there with me. She's always controlled her portions, eaten moderately and lived a healthy lifestyle. My children and I didn't. Eventually, I got tired of how run down I was feeling all the time. Now, I have more energy, and I'm happier."

_ Walter Staib, chef/owner, City Tavern, 2nd and Walnut streets, Old City. 5 feet, 8 inches, 235 pounds.

For Staib, 61, the issue was a simple one.

"I'm getting older, and I wanted to feel stronger and keep my energy level up. I started gaining weight, and I didn't like it."

Staib, who consults with restaurants and companies all over the world in menu and recipe development, got serious about changing his diet and exercise regime two years ago. "I needed some discipline," he said. So he signed on with a trainer at Main Line Health & Fitness on Haverford Road in Bryn Mawr.

"It's made all the difference. I can't cheat, and if I don't show up, I still have to pay. So I show up." Although his weight has stayed about the same, he's turned flab into hard muscle. "I can carry three cases of cookbooks now, instead of just one. And the kids who work for me can't keep up with my energy level. An 18-hour day is no problem."

Staib found that while he has to taste food all day long, at his restaurant, portion control is key. "And when I'm home and in town, I eat light. I'm in the middle of developing 30 recipes for Dietz & Watson right now, and that's tough. But on my own time, I'm careful."

Besides his twice weekly training at the gym, Staib has become a committed walker.

"I love to walk outside. The treadmill, for me, that's like a hamster on a wheel. Outside, I feel refreshed, my creative juices start to flow."

He typically walks from his home in Bryn Mawr to the Ardmore train station and back, a minimum of 90 minutes, almost every day. "It's good for my head. And the rest of me."

_ Matt Levin, executive chef, Lacroix at the Rittenhouse Hotel. 5 feet 10 inches, 260 pounds.

Levin, 34, never had a weight problem. He played lacrosse, stayed active and in good shape. But in the past seven years - "since we had kids" - he's packed on the pounds.

"I just decided enough is enough. I want to be able to play with my kids in 10 years, not be so unfit that I'm on the sidelines."

Spending 14 or 15 hours in the kitchen, devoting little or no time to exercise, and eating late-night dinners in front of the television were all part of the problem. Although the hours aren't going to change much, the rest of it Levin vowed to control. In a month's time, he's dropped 14 pounds, and hopes to lose another 60 or 70.

"In the beginning, I was ridiculously strict with myself. I wouldn't eat anything, just one meal a day, and protein shakes. But I know myself, and if I continued down that road, I couldn't sustain it."

He's become more mindful about what he eats, cut soda from his diet, focused on portion size and eliminated the late-night dinners, choosing instead to eat something light at the restaurant before he heads home to Bucks County.

And with the help of his friend and sous chef Mike Fiorello, Levin works out five or six days a week.

"I get bored easily, so having a workout partner really helps." Levin gets some cardio in every time he's at the gym, including strenuous games of racquetball on Thursdays. "We mix it up, which keeps things interesting."

His team in the kitchen is behind him 100 percent. "Everybody has my back. Even the wait staff and the servers will see me eating something and say, 'Is that on your diet? Is there sugar in that ice tea?' They're breaking my b---- - but it helps." *