When it comes to weight loss aids, the gold standard -- if there is one -- is prescription drugs. That is because the FDA requires that prescription 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 improve.
These requirements have limited the options available because, as is often the case with diet aids, there are questions about whether these results outweigh the potential benefits of the lost weight. The FDA tends to be very conservative about approving weight-loss drugs, primarily because most experts agree that obesity can best and most safely be addressed through lifestyle changes.
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, research shows they may also provide a motivational boost. 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, the FDA will 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.
Orlistat, which is a gut lipase inhibitor, or fat blocker, is the active ingredient in the prescription-only product, Xenical. It's also the key ingredient in a somewhat controversial over-the-counter (OTC) product, Alli, which is 50 percent Xenical's strength. Orlistat 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 calories per day, 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.
Xenical, as noted, is prescription only, but GlaxoSmithKline offers the lower dosage version, Alli, without a doctor's prescription as part of a complete weight-loss system that incorporates the drug, a user-support forum and an online program called MyAlli.com (free subscription required). 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.
Alli's (and Orlistat's) gastrointestinal side effects are well publicized. However, according to a 2011 Obesity study, those unpleasant symptoms may be a positive motivation in some cases. 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 necessity of using the drug to change those behaviors.
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.
There was some negative reaction from consumer advocacy groups to the FDA approving an OTC weight loss drug. Public Citizen called Alli's approval "reckless.
These three weight loss drugs are the newest batch of prescription weight loss pills on the market (Qnexa and Belviq were approved in June 2012, Contrave in September 2014). All three of these drugs are restricted to treating very obese adults (over age 18), with the benchmark BMI (body mass index) depending upon health complications directly tied to excess weight.
Like all weight-loss supplements, total weight lost over diet and exercise alone was modest, and side effects may not be worth the risk. Because these three prescription medications are so new, most medical professionals are reluctant to prescribe them until the side effects of longer term use are known -- especially since post-approval clinical trials and data are still pending.
At this time, the guidelines for medical professionals for all three of these drugs are to evaluate the patient after 12 weeks; if they have not lost at least 3 to 5 percent of their baseline body weight, treatment should be discontinued as the long term risks (seizures, increased blood pressure and heart rate and other serious issues) will most likely outweigh the benefits. They may also interact with other medicines.