By Kathleen Goodwin, RD

Ever since the FDA approved them in 1959, appetite suppressants have been among the most popular prescription weight loss medications sold in the United States. Appetite suppressants work by suppressing appetite and increasing chemicals in the brain that promote satiety. The most widely prescribed appetite suppressant, Phentermine (better known as the “phen” part of the banned drug combination “phen-fen”), along with related medications—such as ionamin, fastin, adipex and tenuate—continues to pull in millions of dollars in pharmaceutical sales yearly.

Are appetite suppressants right for you?

While moderately effective, the decision to take appetite suppressants is serious and should be considered carefully. If you are “trying to lose those last 10 pounds”, these medications are not for you. However, if your BMI is 30 or above, the potential health risks from your excess weight are far greater than the potential side effects from these medications, which makes you a good candidate. Also, if you have a BMI of 27 or above with an accompanying obesity-related condition (e.g. diabetes, high blood pressure, etc.), appetite suppressants may be something to try. (Check your BMI here.)

What are the side-effects of appetite suppressants?

Side effects are important to consider when taking any prescription medication. Appetite suppressants are no exception. Chemically similar to amphetamines, appetite suppressants can likewise cause insomnia, nervousness, restlessness and rapid heart beat. As a result, this class of medications is contraindicated in people who have heart disease and high blood pressure. In addition, remember that these medications are also controlled substances, and while the risk is low-to-moderate, there is a risk that dependence will occur.

How much weight will you lose with appetite suppressants?

With obesity rates soaring, it is clear that our currently approved weight loss medications are no panacea. Research shows that on average, you should expect to lose no more than 5-10 percent of your current body weight while taking an appetite suppressant. That is, if you weight 200 pounds, expect to lose no more than a 10-20 pounds when you use these medications in conjunction with a healthy diet and exercise. Most studies also suggest that after six months of use, weight loss levels off and these medications may lose their effectiveness. Lost weight is often regained when you stop taking these medications, which is why it’s extremely important to learn and practice good eating and exercise habits while taking appetite suppressants.

Conclusion: limited use of appetite suppressants for weight loss

In short, if your health is at risk due to obesity, you may wish to ask your doctor about taking a prescription appetite suppressant medication. Taking prescription weight loss medication in conjunction with a healthy diet and exercise will likely moderately increase your weight loss as opposed to diet and exercise alone – in the short run. However, there is no substitute for a healthy diet and exercise program to keep your body healthy and trim. Nothing worth having comes easy and health is no exception!