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Weight Loss Pills Approved by the FDA

By Andrew Bennett ; Updated July 18, 2017

Searching for effective, safe weight loss pills is a daunting task. Dietary supplements are largely unregulated until after adverse side effects are reported. FDA approved weight loss pills are tested thoroughly and regulated; however, they often carry many of the same side effects as dietary supplements. FDA approved weight loss pills include Xenical, Alli, Meridia, and Phentermine. For best results, always use weight loss pills in conjunction with diet and exercise.


Xenical is another name for the FDA-approved drug orlistat, which is purported to aid in weight loss. This product claims that it is safer than other weight loss pills because it does not affect the central nervous system. Xenical works in the digestive system to decrease the absorption of dietary fat. By blocking the action of the enzyme lipase, which breaks down fats for digestion, Xenical impedes one-third of the fat from being absorbed. However, this can decrease the absorption of the fat-soluble Vitamins A, D, E and K. Reported side effects are oily stool, increased bowel movements, nausea, vomiting, rectal pain, loose stool, and discharge with gas. In August of 2009 the FDA reported that orlistat has been connected with some liver damage.


Alli has the unique claim of being the "only FDA-approved over-the-counter weight loss aid". Half the strength of Xenical, Alli works in conjunction with a low calorie diet and weight maintenance plan by blocking fat. It is stressed that meals not include over 30 percent fat because high dietary fat will increase the side effects experienced with use. These side effects are similar to those of Xenical, including both stomach and intestinal discomfort. Alli claims to have no effect on the liver or heart, backed by a safety record establish in 100 clinical studies on 30,000 patients.


Meridia is a potent appetite suppressant that is chemically similar to an amphetamine. Sibutramine, the chemical name for Meridia, is a serotonin-norepinephrine reuptake inhibitor. This means that it increases the activity of certain neurotransmitters that enhance satiety, making the user feel less hungry. Though in the same class of drugs as many anti-depressants, Meridia has shown no effect on symptoms of depression. A 12-month long Knoll clinical trial showed a 10 pound loss of weight in obese subjects with 10 milligrams a day of Meridia. This compared to a 3.5 pound loss in the placebo group. Side effects include increased heart rate and blood pressure, dizziness, restlessness, and decreased concentration.


Also similar in structure to amphetamines, Phentermine is another appetite suppresent. Phentermine stimulates the hypothalamus to release norepinephrine and other neurotransmitters to decrease appetite. Half of the notorious Fen-Phen combination, Phentermine was not banned by the FDA in 1997 along with its counterpart fenfluramine, which caused heart problems in many users. Phentermine also goes by the names Fastin, Ionamin, and Adipex-P. Side effects include nervousness, anxiety, dizziness, headache, insomnia, diarrhea, and constipation.

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