These seemingly immortal fitness myths are by no means the only fallacies that people believe in. But they are the most common ones I come across in my line of work. It is hard to explain their longevity in spite of the fact that we are no longer living in the fitness information dark ages. But as one reader reminded me, it is important that fitness professionals continue to shoot down these myths because believing in these mistaken notions can be an obstacle to becoming fit.

Exercise and weight loss
Many people work out in the belief that they will get thin. It is true that exercise is a big help in shedding unwanted pounds but it is not the end all and be all in becoming slim (I use the word "slim" to mean normal weight for your particular build; I do not mean "skinny"). What people forget or don't want to hear is that if the calories coming in are greater than the calories going out, it is possible to exercise regularly and still be plump. It is a myth that exercise will "make" you thin. Since many local and foreign celebrities are doing kickboxing, yoga or Pilates, people are always asking me if these kinds of exercise will make them lose weight. My answer? It all depends on how much you are eating. It may seem hard to believe, but I have seen overweight kickboxing teachers. I have also seen plump Pilates and yoga instructors. There are many aerobics instructors who teach several classes a day but are still overweight. It's all a matter of how much is coming in compared to what is going out. If you believe that exercise alone will make you thin, you will be in for a rude surprise. If you do not make an effort to cut back on excess calories, you will be fit but fat.

Exercise and body shape
A myth that eventually disappoints many people is that through exercise you can have the body of your dreams. The truth is that exercise can make you fit, but it cannot give you the body of Cindy Crawford or Brad Pitt unless you also have similar genes. So even if you follow the exercise and diet program of your idol, your body will only change as far as your own genetic potential.

There are limits to what exercise can do to change your basic body shape. For example, you can only make your hips as small as your hip bones are wide. Aside from skeletal structure, exercise cannot change skin elasticity and cannot get rid of certain tenacious pockets of fat that are distributed according to your genetic inheritance. It is very possible to be of normal weight and have a high fitness level and still have a small pouch of fat somewhere in your body. Exercise cannot "fix" sagging abdominal skin, a common problem in women after childbirth.

Breast size is another example of the limits of what exercise can do. Since breasts are approximately half fat and half milk glands, you can reduce your breast size by losing body fat but you cannot make them bigger by doing chest exercises. However, the chest muscles can become bigger and, thus, make you look like you have fuller breasts.

It is important to have a realistic expectation of what exercise can do for your looks so you don't get disappointed and quit working out.

Protein and muscles
Many people (usually men) believe that the more protein they eat, the bigger their muscles will become. While it is true that someone who lifts heavy weights has a higher protein requirement than someone who is sedentary, it is not true that eating lots of protein will automatically give you bigger biceps. You see, muscles get bigger and stronger in response to the demand put on them (translation: how much you lift). Exactly how big they will get depends mostly on the male sex hormone testosterone and your genetic build (tall lanky people have a harder time building muscle mass compared to short stocky people). Since muscles are 25 percent protein and 75 percent water, an adequate supply of protein is essential for the muscle fibers to become thicker. However, protein is not the reason why the muscles get bigger, it is just the building material. A good analogy can be made with building a house. No matter how many truckloads of construction material (protein) are delivered to your construction site, your dream house will not materialize unless you have enough workers (weight lifting program). On the other hand, no matter how many workers you have, if you don't have enough construction material, you still cannot build the house. If you don't pump iron but stuff yourself with protein, you will just make your fat cells bigger. You can lift all you want, but if you don't have an adequate supply of protein, you still won't get your muscles as big as you would want them to be. What is an adequate supply? Current recommendations for people who lift weights are 1.2 to 2.0 grams of protein per kilogram of body weight a day. Keep in mind that protein does not come only from animal sources. It is also found in grains, beans, and vegetables.

Weight lifting and women
Most women do not want to look like a man. So I can understand why many women are scared to lift weights. They believe that they will get as muscular as their husbands or boyfriends. But this fear is based on a myth. There are a few exceptions, of course, but in general, women do not have the genetic potential to build big male muscles. So what about those gigantic muscles you see on female bodybuilders? Well, they are either one of the genetic exceptions I mentioned above or they are taking anabolic steroids.

I don't want to give the impression that women cannot make their muscles bigger with the appropriate program (more weight, less repetitions, many exercises and sets). They can, but no where near as big as a man of the same height and build.

Weight lifting and the elderly
It is too bad that the myth that only the young can lift weights continues to live on because middle-aged and elderly people are the ones who would benefit the most from resistance/strength training. Loss of muscle mass as people get older is one of the major reasons why it is so easy to gain weight after the age of 30 (lack of physical activity of any kind is the other). It is also the main reason why the elderly are so frail. The myth is hard to shake off because we continuously see advertisements for fitness products using young hard bodies. The reality is that soft flabby older bodies need resistance training the most. Not for vanity but for function and independence. If you want your body to remain "young", meaning being able to do the same activities as your younger years, you would be very wise to invest in a weight training program.