We have all heard of those new diets, Atkins, low carb, high protein etc. Some of us have tried them with good results. There's no doubt about that they work.

They all have one thing in common though - they give us the impression that we no longer have to think about, or bother about, calories.

Nothing could be more far from the truth, unfortunatly. Calories still do count! What these new diets basically do is that they make you feel more satisfied on fewer calories. There are no mystical ingredients or unknown secrets that can change the law of energy balance. In other words, nothing will ever change the fact that if your metabolic system doesn't consume more energy than you take in, you will gain weight. If your metabolic system consumes more energy than you take in, you will lose weight. Period. The universe is made that way.

What are calories then? Are they some small evil molecules hiding in the food, just waiting to invade your body and make your life a fatty hell? No, of coarse they're not.

A calorie is just a word that defines a certain amount of energy, nothing else.

One calorie is the energy it takes to heat one gram of water one degree celcius. Mostly on food packages, the amount of calories are presented as kcal, which means kilo calories i.e. 1000 calories. So, one kcal is the energy it takes to heat one kilo, or one liter, of water one degree celcius. When a fitness chart or table says you burn for example 250 calories per half hour when jogging, it means 250 kilocalories.

Since calories are energy units, they apply to all kinds of energy, not only food. For example lighting a 60W lightbulb obviously takes some energy. The energy it takes to light it for 1,5 hour equals the calories you'll get when eating 1 piece of cheesecake! If you could fill your car up with BigMacs, you could travel almost 0.5 mile on one BigMac!

Does this knowledge make us any happier? Perhaps not but it can give us an idea on how different excercises will burn calories. Calories are consumed by performing work, in physical meaning. The amount of calories consumed equals power multiplied with distance, power x distance.

What does it mean? It means that the higher the power applied to an exercise and the longer the distance this power is in effect, the more calories are burned.

You can easily see that this explains why low intensity training like walking can be very effective, provided the distance is of significant length. You can also see that if you apply more power i.e. higher intensity, you will burn more calories compared to walking slowly the same distance.

Many people avoid to start excercising because last time they made an attempt they started at a high intensity level. The result is horrorful memories of short-of- breath, nearly- fainting, close- to- death feelings. The assumption that high intensity is the only way to burn calories is probably the reason most of us never develop a habit of regular exercise.

Next time you decide to improve your fitness level, remember the formula power x distance. Start by walking in a pleasant pace in let say half an hour three times a week. Increase the time (distance) by a quarter of an hour for the next three weeks.

After four weeks you will feel better, look better and healthier and you will also discover that you have automatically increased your walking speed. Without even notice. What does that mean? It means that you have automatically increased the power factor in the formula wich in turn means more calories burned!

The next step in your training program is your own choise. You can either increase distance or pump up your walking speed. If you have the time, why not both?