Power to you
It's probably safe to say that people aren't consuming energy bars because they're delicious - they tend to be rather dry, although they make a good occasional snack with a cold glass of milk (without melamine, please!). And they're certainly not eating them because they want to lose weight; energy bars, which are also known as power bars, pack a lot of calories into a small amount of food.
Although they look similar, energy bars differ from granola bars, although a few of the ingredients are the same. Both usually contain nuts, dried fruit (such as raisins, apples and cranberries), sweeteners and carbohydrates such as oats and wheat but energy bars also have protein (in the form of dried milk, soy or yogurt) plus vitamins and fibre. Some producers also add other high-calorie food such as chocolate and peanut butter; others include caffeine, in case your brain is also in need of energy. Several companies are paying heed to those with dietary restrictions and are making nut- and wheat-free energy bars or adding artificial sweeteners rather than 'natural' ones such as sugar and honey.
While energy bars are usually highly nutritious, they shouldn't be used as a substitute for all your meals - they're meant to supplement your diet, not replace 'real' food. They tend to be extremely sweet, often containing more than 25 per cent sugar (one of the reasons they give you energy).
Consuming these bars won't give you the six-pack abs of the models on the boxes: for that, you also need to do a lot of work. Look for those that suit your energy needs: some have higher amounts of protein (to build muscle), others have more carbohydrates (for endurance). Because they are individually packaged, it's easy to toss one into a backpack to take on long hikes or bike rides - but don't forget a bottle of water, which not only makes the energy bar easier to eat but also helps to prevent dehydration.
Energy bars can be found in supermarkets but the best selection is available at health food and sporting goods shops.