When it comes to weight loss aids, the gold standard -- if there is one -- is prescription drugs. That is because the FDA requires that drugs marketed for weight loss must produce weight loss that is greater than or equal to 5 percent of that lost by subjects taking a placebo for one year, or show that more than 35 percent of the subjects achieve greater than 5 percent weight loss and show that this is approximately twice the proportion (and significantly different from) the control/placebo group. In addition, lipid, glycaemia and blood pressure profiles must approve.
These requirements have limited the options available. Meridia was taken off the market in October 2010 after it was linked to increased cardiovascular risk, specifically of heart attacks and strokes. There is some question about whether these results outweigh the potential benefits of the lost weight. Also in the latter half of 2010 and January 2011, the drugs Qnexa, Lorqess and Contrave were not recommended for approval by a FDA advisory board because they produced unimpressive results that did not outweigh the risks. As two UK researchers point out in their review of substances used in weight loss drugs in the journal, Pharmacology, Biochemistry and Behavior: "As obesity is not itself a disease, poses no immediate threat to life and can be addressed without risk by diet, exercise and lifestyle changes, albeit ineffectually foremost in the long term, a high degree of safety is required of anti-obesity treatments."
So why not just rely on diet and exercise? In general, 5 percent to 10 percent is the magic number for clinically meaningful weight loss that lowers disease risk, and many of these drugs provide modest results when used with diet and exercise modifications. However, these drugs may not only help patients achieve weight loss faster, they may also provide the motivational boost to keep them on the path away from obesity. Doctors who treat obesity say that prescription weight loss drugs give their patients added motivation to change their behaviors long term.
Since the FDA regulates diet pills, their safety is under ongoing scrutiny. As new reports of possible risks are published, they take action. A case in point is Meridia. The FDA asked Abbott Laboratories to pull the drug in October 2010 after a New England Journal of Medicine study published in September 2010 showed that Meridia users had an increased risk of heart attack and stroke. Even though Abbott took issue with the study's methodology (Abbott says many of the study's participants shouldn't have been using the drug) and with its results (the company says that in 46 clinical trials and 6 million patient-years of use, Meridia hasn't shown excess cardiovascular risk), they complied with the request. The Meridia situation also shows that after long-term use in the population, issues -- such as increased disease risk -- may come to light. The bottom line: There may be some risk when taking these drugs, even though the FDA tries only to approve drugs that it deems effective and where the benefits outweigh the risks.
And while the peril in an approved drug might be less than with unapproved diet supplements, the side effects are many. The biggest decision is whether you want to live with them. Oily stools and fecal spotting and urgency are consequences that can change the way you live.
Alli and Xenical are the only two FDA-approved diet pills. Alli is the over-the-counter version of the prescription-only Xenical (it is 50 percent Xenical's strength). The active ingredient in both of these drugs is Orlistat, which is a gut lipase inhibitor, or fat blocker. It works by reducing the amount of fat our bodies absorb in the digestive system and eliminating it through bowel movements, which is why many of Orlistat's side effects are altered bowel activity. The suggested triggers for a patient to start using this drug are a history of failed weight loss attempts using the standard behavioral method of a smart diet and exercise regimen, and the loss of at least 2.5 kilograms or 5.5 pounds using diet and exercise in the month prior to the first prescription. In addition, it is suggested that those taking Orlistat reduce their calorie consumption by 500 to 1000, and the amount of fat they consume to 30 percent of their diet.
Orlistat's side effects include oily stool, fecal spotting and urgency, diarrhea, flatulence, chronic or recurrent pain in the upper abdomen, increased abdomen fullness and indigestion. In addition, Orlistat interferes with drugs and fat-soluble vitamins, such as A and D, which calls into question its ability to be used long term. Some critics question the usefulness of a diet drug that can be tolerated by most users only in conjunction with a low-fat diet. GlaxoSmithKline markets Alli as part of a complete weight-loss system that incorporates the drug, a user-support forum and an online program called myalliplan. Because of Alli's side effects (referred to as "treatment effects"), potential customers are warned to assess their level of commitment to a low-fat diet before they decide to use the drug. Those who do are encouraged to buy an Alli starter kit (*Est. $45 to $120, depending on the number of pills) which includes a bottle of capsules, a carrying case, six information booklets and a code to access myalliplan.
There was some negative reaction to approving an OTC weight loss drug. Public Citizen called Alli's approval "reckless," and ConsumerAffairs.com's health advisers counseled caution. Alli's gastrointestinal side effects are well publicized. However, according to a 2011 Obesity study, those unpleasant symptoms may help change a person's behavior so that long-term use is unnecessary. The report found that those who used the drug no longer felt that their only option to combating obesity was through a medical solution; they decreased their unhealthy eating habits and accepted any unpleasant consequences as a result of their eating behavior and the drug.
Users posting to Amazon.com and Drugstore.com may drive this point home. Many of the most positive reviews mention the drug's side effects. Several users say that the potential for oily spotting or other bowel issues helps them remember to keep the fat content of meals within the recommended limit of 15 grams. Others say they find the side effects inconvenient, embarrassing and even physically painful. These side effects are pretty uncomfortable for what can best be described as modest weight loss. According to Dr. Donald Hensrud, a preventive medicine and nutrition specialist at the Mayo Clinic in Rochester, Minn., the average weight loss after a year's use of prescription-strength Xenical is 6 pounds more than with diet and exercise alone. Because Alli is only half the strength of Xenical, Hensrud estimates that it could lead to an annual weight loss of 3 pounds more than what a user would get with diet and exercise.
This modest weight loss might not seem to be worth the side effects many users describe. But Alli is an over-the-counter weight-loss aid for which there is clinical data. Its known side effects have been documented. In 2006, Public Citizen petitioned the FDA to remove both Xenical and Alli from the market, saying these drugs could be harmful. While they haven't been removed from the market, in August of 2009, the FDA issued a statement saying it is reviewing safety information after getting 32 reports of serious liver injuries between 1999 and October 2008. Six were cases of liver failure, and 30 of the reports occurred outside the United States. The most commonly reported adverse events described in the 32 reports were jaundice (yellowing of the skin or whites of the eyes), weakness and abdominal pain; 27 of the cases resulted in hospitalization.