Over-the-counter Weight-loss Aids

According to the Consumer Research website, ingredients found in over-the-counter weight-loss pills are either unsafe or unproven. In most cases, you're better off changing the way you eat and exercising more in order to lose weight. The Mayo Clinic points out that most of the ingredients commonly used in weight-loss pills have not been properly studied, so there is insufficient evidence to know whether they work. Before starting any diet or exercise plan, consult your physician.

Alli

Alli is the only FDA-approved diet pill that can be bought over the counter. Alli is a milder version of orlistat (Xenical). Orlistat is sold only with a prescription. Both Alli and Xenical work by blocking part of the fat you consume. As fat cannot be absorbed, it passes through the intestine undigested, thus reducing the amount of calories you get from the foods you're eating.

Alli can cause some unpleasant side effects, including gas with oily discharge, diarrhea and uncontrollable bowel movements. To avoid these problems, you should adhere to a low-fat diet.

Exercise is also important to help with weight loss while taking Alli. According to the Mayo Clinic, people taking Alli over a year's time lost about 3 to 5 pounds more than people who used diet and exercise to lose weight.

Hoodia Study

Insufficient evidence and information exist to know whether most weight-loss supplements are effective or safe, reports the Mayo Clinic. Hoodia is an example. The only double-blind study that exists in humans was conducted by Phytopharm, a supplements' manufacturer. While the study was never peer-reviewed, results showed that people taking Hoodia ate less and experienced a reduction in fat mass, according to eMedTV.

The study doesn't say whether people also lost weight. Since no information is available on the safety of the product, talk to your doctor if you decide to try Hoodia, especially if you have a medical condition.

Other OTC diet pills that haven't been sufficiently studied include chromium, chitosan and bitter orange, according to the Mayo Clinic.

Conjugated Linoleic Acid

A few over-the-counter weight loss supplements might produce some weight loss, although studies sometimes provide conflicting results. A 2007 study published in the "American Journal of Clinical Nutrition" showed that conjugated linoleic acid, or CLA, produces a modest loss of body fat.

The study was a compilation of previous studies, and analyzed the positive and negative results found in several trials. However, an article in NaturalNews.com estimates the weight loss benefits of CLA supplements to be about 2 to 3 pounds a year and thus not important enough to be relevant.

Side Effects

Alli is the only over-the-counter weight-loss aid that clearly identifies possible side effects on the label. Most other supplements do not volunteer this information.

According to "Science News" magazine, most people don't report their problems with diet pills, so it's difficult to know their experiences. Side effects can range from insomnia and gastrointestinal problems to elevated blood pressure, stroke and death, according to "Science News."

Precautions

eMedTV recommends choosing products that contain a list of ingredients, so you can research each one on its own and see the benefits and warnings.

Don't rely on claims or recommendations from companies that sell weight-loss supplements; instead talk to your doctor about what options might be best for you. Avoid taking weight-loss aids if you have a serious medical condition, are pregnant, breastfeeding or are taking any prescription drug.