Strange or extreme diets can be very dangerous, and they are often ineffective. If one seeks the sensible and popular ideal of being lean and athletic, then starvation diets are counterproductive. Diet pills There are many diet pills for sale, some which are associated with comprehensive dietary programs. Many such pills, including many of those containing vitamins and minerals, are not effective for losing weight. Some drugs enable short-term weight loss, usually with unpleasant and potentially dangerous side effects. The drugs include herbal products available at health food stores, as well as over-the-counter and prescribed medications provided by doctors and pharmacists.Typically these drugs fall into two classes: diuretics to induce water-weight loss and stimulants (such as ephedrine, and more recently synephrine, due to the former's ban as a weight loss supplement by the FDA, although ephedrine is still available as an asthma medication) to increase heart rate and reduce appetite.

Both classes of drugs can cause kidney and liver damage, and stimulants can cause sudden heart attacks, addiction, and both ephedrine and synephrine have been proven to cause ischemic stroke.

Yo-yo dieting
Yo-yo dieting is defined by alternating periods of feast and famine that the dieter deliberately undertakes. It is a particularly ineffective method of sustaining weight loss.

The human body responds to starvation by decreasing metabolism. When food is again available, it is stored immediately as fat. This survival mechanism, while a useful response to genuine food scarcity, leaves the yo-yo dieter feeling lethargic and fatigued.

Metabolism can be restored to a higher level with exercise and a sensible weight-loss diet. This diet is defined by the minimum safe daily caloric intake of 75 percent of the basal metabolic rate or 4200 kilojoules (1000 Calories), whichever is greater. (Those eating less should do so only under medical supervision. Parents and guardians should consult medical professionals before placing their children on any type of diet.)

Once an ideal weight is attained, a weight-maintenance diet is essential. This requires limiting excess caloric intake and making small changes in caloric intake in response to physical observations of one's weight and appearance.