Wouldn't everyone love to stop worrying about dieting? Just take a pill once a day and forget about it. The pounds just melt off. Well, nutritional science isn't quite there, yet. But it is making strides. However, anyone considering their use should be aware of both the risks and the potential benefits.

Pharmaceutical companies have taken two basic approaches to weight loss pills: those that stimulate and those that block. Stimulate what? Block what?

Appetite Suppression

In the first category are diet pills that work on the centers of the brain to stimulate the central nervous system. Several years ago these were variants of amphetamine, popularly known as 'speed'. The basic idea was to stimulate the dieter, which had the 'side effect' of suppressing appetite.

The idea is sound. Eat less and your odds of losing weight are higher. The basic equation of dieting, no matter what method is chosen, remains the same: more calories consumed than used leads to weight gain. Consume fewer calories than you burn and the body will naturally shed pounds.

But, as with any drug, there are real side effects. Speed can produce heart palpitations, insomnia, diarrhea and lowered sexual function. In extreme cases, it may produce psychotic episodes. Over time, even the ability to depress appetite generally fades. Once the effects of amphetamine became more widely recognized, its use was discontinued.

A more contemporary prescription diet pill in this category is phentermine. It works by stimulating the hypothalamus, a gland that controls certain neurotransmitters associated with appetite. But it also plays a role in the sleep cycle, so sleeplessness can result. Still it is generally safe for short term use and the side effects are much less severe. Over a few weeks time, the desired appetite suppression is likely to fade.

Fat Blockage

The second category of weight loss pill uses an entirely different approach to eating and digestion. Here, there's no attempt to regulate how much food is consumed, only how many calories are retained. Since every digested fat gram yields 9 calories, it is 'energy dense'. So, removing fat from the system can help reduce the number of available calories.

Orlistat (marketed under the brand name Xenical) is a prescription diet pill that does just that. It operates by altering the body's efficiency for absorbing fat, causing more of it to be eliminated in feces. The popular non-prescription drug, Alli, is the same drug at a lower dosage.

But, these too have side effects. Stools tend to be oily (a result of the added fat) and defecation is more likely to be spontaneous. That means it's possible to lose control of the bowels and eliminate at undesired moments.

Summary

For many, the side effects of diet pills are well worth the benefits they give. Many users have tried a number of diet plans and find they don't work well enough or require too much willpower. Others simply prefer to spend less time thinking about meal plans, carb to fat ratios or total calories consumed. A pill helps them diet with greater ease.

As with any approach to dieting, it's wise to consult with your physician first before selecting a weight loss pill.