How Do Fat-blocking Diet Pills Work?

Obesity poses a significant threat to health. Consequences of obesity include the development of type 2 diabetes, cardiovascular diseases, osteoporosis, osteoarthritis and cancer. Prevention of obesity involves a lifelong commitment to controlling calories, curbing food portions and making healthful food choices. Though not always effective, fat-blocking agents may help manage energy intake and encourage the adoption of behaviors that assist in long-term weight management.

Fat-Blockers and Digestion

Digestion is the process of reducing food to its simplest nutritional forms. Mechanical digestion refers to the chewing and mixing of food, while chemical digestion describes the action of digestive juices such as enzymes, which are biological proteins that hasten the digestive process, on nutrients. Fat-blocking agents are taken orally with a meal containing fat for the purpose of disrupting chemical digestion of dietary fat.

Fat-Blockers and Fat Absorption

Gastric and pancreatic lipases are specific groups of enzymes that digest lipid (fat) to its simplest forms (fatty acids and glycerol). Fat-blocking agents inhibit the activity of these enzymes. Lipid particles remain trapped in the intestines because their size prohibits their passage from the intestines into the body. This condition is referred to as fat malabsorption.
Drug-induced fat malabsorption necessitates lipid excretion in the feces. Loose or oily stools, urgent diarrhea and stomach and rectal pain may appear as consequences. Though undesirable, these side effects may prove beneficial in that they encourage the consumption of a reduced-fat diet while taking the drug. This behavior, if adopted permanently, may help manage weight even after the drug is discontinued.

Fat-Blockers and the Liver

Because the drug operates predominantly in the digestive tract and is excreted almost completely in the feces, systemic (whole body) drug activity is thought to be negligible. Nevertheless, a number of suspicious cases of liver injury in prescription drug users recently prompted the FDA to reiterate the importance of using lipase inhibitors as directed and reporting any adverse effects immediately.

Fat-Blockers and Weight Control

Calories enter a body upon absorption of nutrients from the small intestine. Inhibiting fat absorption reduces energy (caloric) intake and possibly body weight over time. The prescription fat-blocker Xenical, when taken with a balanced, reduced-calorie diet, inhibits fat absorption by about 30 percent. Despite media hype, the over-the-counter drug Alli, containing only a fraction of the dose of its clinical counterpart, is thought to be less effective.