My friend, Stefan, came to me with a problem.

He had been on a popular diet for about six months, and he looked pretty good. He had dropped 30 pounds and was well on his way to taking off the additional 20 that would bring him to his target weight. But he complained that he was feeling weak much of the time. Carrying heavy boxes or even full bags of groceries from the car to the house taxed his strength in a way it never had before.

Stefan wondered if perhaps there was some critical nutrient he wasn't getting enough of on the diet. Or, was age simply catching up with him?

I asked him a few questions, looked him over for a moment or two, and had him perform some simple physical movements.

"I have good news and bad news," I told him. "Bad news first: You've not only lost fat on this diet, you've lost some muscle. It's not good to lose muscle."

Stefan's worried frown revealed that this was not something he wanted to hear. He had lost all that weight in order to look good, feel healthy and be more energetic. Now here I was telling him that he was, in effect, wasting away as a result of his positive intentions.

"So what's the good news?" he asked forlornly.

"The good news is you can build your muscles back up and still lose all of the weight you want. You just have to re-orient your activities so that you lose fat, not muscle. Better yet, you need to do some things--and I'm talking exercise--that will make your muscles stronger and bigger even as you continue to take off fat."

Stefan didn't really want to hear about exercise. He had done well losing weight by dieting alone. I could see he was proud that he had been able to shed an average of five pounds a month while enduring no more exercise than an occasional short stroll around the block.

Nevertheless, the news that he was losing muscle was a sufficient shock to get him to agree to let me put him on an exercise program.

You see, many people are like my friend. They have the false idea that when you diet, your body consumes its stored fat--and only the fat.

The truth is, unless you're exercising or otherwise being physically quite active, your body on a diet may begin feeding on both fat and muscle. The more severe the diet and the quicker the weight loss. the more danger there is of serious muscle loss. This is turn can actually make it harder for you to lose weight as time goes by.

Let's take a somewhat extreme example to illustrate the problem.

It is said there are enough calories in four pounds of body fat to fuel a person for approximately one week. But if you fasted for a week, eating nothing and drinking only water, you would not lose anywhere near four pounds of fat. Your body would instead go into a physiological panic and begin breaking down muscle to meet its energy requirements. Not only that, the decrease in muscle mass would reduce your body's calorie needs, making it harder to lose weight in the future by dieting!

Your real goal in dieting for weight loss is to lose fat while building muscle. You can achieve this through the proper kind of exercise.

Working out with weights is a great way to maintain and build your muscles. You don't have to fancy yourself a bodybuilder or spend hours upon hours in the gym to gain the benefits of weight training. Nor do you need a lot of expensive equipment. You'll be amazed what a basic set of dumbbells, used for twenty or thirty minutes a day, three days a week, can do.

One tip: If you are trying to lose pounds, don't make the mistake of going overboard with the weight lifting in an attempt to quickly build the biggest muscles you can. You'll just end up with the opposite problem of my friend Stefan: lots of muscle, with more pounds! Go for fewer sets of a given exercise than the person who is deliberately building massive muscles. If the budding Mr. Universes would normally do four or five sets, you can stop at one or two.

I'm happy to report that Stefan today is in better shape than ever. He's not only reached his target weight, he has the strength and energy to enjoy his trim new body. True, the rate of his weight loss slowed down a bit as he added weight training to his life, but that's OK. He got where he wanted to go--and didn't leave his muscles behind in the process.