After all the years I have spent trying to look my best by consistent attention a healthy lifestyle with regular exercise and proper nutrition, it's pretty frustrating when I hear somebody attributing my looks at 50-plus totally to genetics! I've worked plenty hard over the past 30 years to improve my health and my body as well as my emotional well-being, and the older you get, the more difficult some of it can be. But when you understand that you control your health and fitness, when you make the commitment and put your priorities in order, you can do it and feel a wonderful sense of accomplishment. It is hard work, but it's worth it.

Of course, genetics does set some limits. Certainly, you can't change your body type. If you're a 5-foot-tall endomorph with a lot of excess fat cells, you aren't going to change yourself into a tall, thin ectomorph. You can change quite a lot, but you just can't change into somebody you aren't.

Because we live in such a fitness-conscious age, some women I talk to compliment me on how I look and how I stay in shape and immediately want to know how I do it so that they can improve their own looks and fitness level. But others have tried so many diets that failed, are so fed up with the up-and-down yo-yo experience of losing weight then gaining it back again, that they have just about given up hope. When they see somebody in great shape, it just makes them feel worse.

Actually, I understand how these women feel better than they might imagine. Sometimes when I get a compliment, I wonder what the person would have thought if she could have seen me in high school. I was about 35 pound overweight and was once described by a friend as "chunky." I had the same genetics I do now, but I didn't exercise at all and my eating habits were atrocious.

After I had my daughter, I did what so many women do who feel themselves to be too heavy --- I went on a terribly strict and ultimately unhealthy crash diet. The case of the late Karen Carpenter has shown us what the results of that mentality can be, but I was more fortunate and pulled out of it before I became seriously ill.

As a nutritionist and model, I obviously can't afford either of these extremes. So I have worked out a lifestyle program not only of weight loss, but of long-term weight control. This lifestyle approach can work for you, too.

The first thing to realize is that what we all need is a healthy lifestyle incorporating weight control rather than a specific program of weight loss. What's the difference? Weight-loss diets are concerned only with losing bodyweight, but weight-control programs address long-term eating and exercise habits as well as paring bodyfat when necessary, without sacrificing invaluable and shapely muscle mass.

Weight control involves two things: eating and exercise. You can't control your weight unless you eat properly, the right kinds of foods in the right amounts. Trying to keep your body trim, shapely and in good condition without the right kinds of exercise is futile.

When I was studying nutrition in college, I was constantly impressed with how complicated the body's metabolic systems are. But when you are talking about the practical aspects of weight and body control, you can take a much simpler approach:

• Think of protein as the material for building and maintaining the structure of your body.
• Think of carbohydrates as fuel.
• Think of fats as energy in such concentrated form that they have to be kept to a minimum in your diet, while you emphasize good fats such as omega 3 fatty acids.

Once you understand how to vary the amounts and proportions of these nutrients in your eating plan, you can decrease your bodyfat while maintaining crucial muscle tissue. To lose bodyfat, you need to reduce calories to the point where you are using up more energy than you are taking in from food. But too many dieters forget that their bodies require a certain amount of protein to maintain and repair their bodily tissues, and they cut protein while they are cutting calories.

Don't do it. Keep your protein levels constant whether you are trying to maintain or lose bodyweight. How much protein do you need? Well, the US government's recommended dietary allowance (RDA) is one gram of protein for every kilogram (2.2 pounds) of bodyweight. This may be okay for relatively sedentary people, but recent studies indicate this is not enough protein for those who exercise regularly or those trying to lose weight. There are several reasons for this:

• Exercise puts considerable stress on the muscles, and more protein is needed to rebuild and repair these tissues.
• The body always burns some amino acids as energy, and the more you exercise, the more protein is going to be metabolized for energy.
• When you diet, you want to lose the fat but spare the muscle. Women need muscle tissue for strength for everyday activities and for an active lifestyle. Muscle also provides shapely curves and burns calories even when you're at rest, which keeps your metabolism higher and helps you lose bodyfat and avoid regaining it. This is the advantage of a leaner body composition. It's not just how much you weigh that matters, but how much lean muscle you have compared to how much bodyfat.

Add to this the possibility that everyone needs more protein than the RDA but we just haven't been aware of it until now. How much protein do you really need? A rule of thumb for the average person who exercises regularly is one gram of protein for every pound of bodyweight. This also applies to those cutting calories to lose weight.

Okay, if you are keeping your protein constant, how do you cut calories to lose weight? Once you have reduced the fat in your diet, if you are going to maintain your muscle structure by keeping your protein intake steady, then the only calories left to cut are those you get from carbohydrates. I'm not advocating low-carbohydrate diets where the carbs are already super low. Active people need a certain amount of carbohydrates for energy. I eat plenty of carbs, even when I'm trying to lose weight.

The trick is not to cut your calories too drastically even when you are trying to lose weight. If your intake is 200 calories a day below your maintenance level, you will eventually lose a pound of fat in just over two weeks. And medical science tells us that individuals who are moderately overweight cannot lose more than about a half pound of pure fat a week without sacrificing some muscle in the process, meaning loss of body shape!

Then, of course, there is exercise. When you exercise you burn calories (mostly carbs, some fat, and a small amount of amino acids/protein). So if you exercise regularly, you can burn up extra calories during your workout and, in addition, you will have speeded up your basal metabolic rate so that you will continue to burn extra calories after you've stopped exercising.

The result is you will lose weight slightly faster than a half pound a week. Not much faster, just slightly faster. But you will also have stimulated your muscles so that they will maintain their structure or even grow, rather than atrophy as they will if you don't use them on a regular basis.

As a practical matter, weight control is simple. Cut fat intake, maintain protein, and vary your carbohydrate intake. But, again looking at this practically, putting this program into practice can be a lot more difficult than it looks. At least that's what I've found in my own experience.

Many valiant attempts at dieting fail simply because the dieter can't put up with the feelings of deprivation. Many people are overweight because they eat the wrong things - - high-sugar, high-fat, heavily processed food. When you consider that the caloric maintenance level for a sedentary woman may be as low as 1,300 calories a day, you can see that becoming and staying lean involves changing a lot of your eating habits as well as just cutting calories.

Deprivation diets are difficult because:

• You feel bad while you're on them, and
• You can't continue to eat that way after you've lost your weight, so you end up gaining back everything you've lost -- and usually some more besides.

To avoid this feeling of deprivation, I include as many natural, high-fiber foods in my diet as possible so that I feel full and satisfied after a meal. Foods like potatoes, brown rice, fresh vegetables and fruits, even pasta. Sure, I avoid high-calorie additions such as butter, sour cream, creamy dressings and so forth, but it's funny how quickly you get used to doing without them.

Our taste buds are especially sensitive to three things: fat, sugar and salt. Once you are used to high levels of these elements, natural food can seem almost tasteless. But cut down on your intake of fat, sugar and salt for a while and suddenly your taste buds begin to appreciate the sweetness of an apple, the richness of steaming-hot broccoli and the gusto of freshly cooked pasta.

It's like walking out of the glare of the noonday sun into a dimly lit art museum. It takes some adjustment before your eyes can appreciate the works of art that fill the galleries.

Incidentally, I'm not a fan of fruit juice. A large glass of orange juice contains most of the calories of five or six oranges with virtually none of the fiber. If you like fruit, eat whole fruit, but avoid juice if you are watching your weight.

Losing weight involves learning to eat correctly, not just cutting calories. If you don't improve your eating habits while you are on a diet, you will not be able to maintain your weight after you have reached your goal. So I recommend lifestyle changes with a two-stage approach:

• For the first two weeks, be very strict with yourself. Make sure you eat right and keep your calories reduced. Don't worry about feeling deprived -- you can stay on almost any program for two weeks.
• After the second week, begin to create your long-term maintenance program. Experiment and find which high-bulk, low-calorie foods give you the most satisfaction. If you find you miss certain foods very badly, go ahead and treat yourself -- in small amounts. You love ice cream? Reward yourself for how well you are doing and have a small dish. Is cheesecake your favorite? Have a small slice every once in a while. After all, you are trying to control your weight, not drive yourself crazy.

And make sure you exercise on a regular basis. You'll feel better, lose weight faster and you'll look a lot better, too. Once you have lost the weight, stay pretty much on the same sort of eating plan you have been developing during your weight-loss period. Maybe you will treat yourself to a few more rewards or be less strict with yourself when you go out to dinner, but remember this: What works to help you lose weight is exactly what works to help you keep the weight off.

The only other thing to add is a word about the psychology of dieting. You can deprive yourself mentally as well as physically. Studies have shown time after time that positive reinforcement -- reward -- is much better for motivating people than negative reinforcement -- punishment. If you look in the mirror and say, "You look fat, you look awful, you have to diet!" you are going to make yourself feel so miserable that the next thing you know, you'll be trying to improve your mood with food.

Instead, think positively. Think of how good you're going to look when you've been eating properly and cutting calories slightly for a few weeks or months. Reward yourself psychologically for having made the decision to change the way you eat and the way you look.

As your new lifestyle progresses, don't kick yourself because you aren't losing weight as fast as you would like. You have established a program of nutrition and exercise you can live with the rest of your life, so how you look this week is not as important as continuing to develop the habits that will stay with you for a lifetime.

Be realistic about your goals. You aren't going to turn into somebody else no matter how correctly you eat and exercise. But you'd be surprised how much small changes in your body can contribute to your feeling of well-being and self-esteem.

Remember too that nobody can go on a program like this without messing up once in a while. Just go back to your good eating habits right away and don't let one mistake discourage you.

Dieting for weight loss is essentially a temporary thing. Eating and exercising to improve your body is a lifestyle. The way I look now may be the product of 30 years learning and hard work, and I may have gotten good enough results that I've been on the cover of national fitness magazines, but I consider how I look now to be a temporary stage on the way to how I want to look in the future. As I grow older, I'd like to continue to improve my body just as I want to increase my knowledge, grow spiritually and be the best role model for my children and grandchildren that I can be.