“Just give me a pill, doc.” I hear it all the time from people who are frustrated with their weight and have heard about a neighbor, coworker or second cousin losing weight with the aid of a diet pill. Sounds great: Pop a pill and the extra pounds are gone. But upon closer inspection, the long-term side effects may not be worth the short-term weight loss. 

Here are my thoughts on three drugs that get a lot of press.

Phentermine

My patients frequently ask for phentermine—a popular weight loss medication available by prescription. It has recently been combined with topiramate in the new medication Qsymia. Phentermine is an amphetamine, and it helps people lose weight by suppressing appetite. It does not magically melt the weight off, and it does not help people learn healthful weight management habits. And here’s another reason it’s not effective for long-term weight maintenance: After about three months, your body will have developed a tolerance to it and it will no longer work—even if you stop the medication and restart it. 

Because it is an amphetamine, phentermine makes some people feel jittery or anxious. It can cause insomnia and in some instances a serious side effect called pulmonary hypertension. Pulmonary hypertension in its most severe form can lead to heart failure. Your body can develop a physical dependence to phentermine, which can cause depression and fatigue when you stop the medication. Studies show that because people's eating habits do not change when taking the medication, their weight loss does not last either. 

Xenical

So maybe another pill would work better? Let’s examine Xenical. Xenical works by blocking 30 percent of fat absorption in the gut. Side effects include fecal incontinence and oily spotting on underwear. Sound pleasant? Not so much. Also, Xenical does not differentiate between good fats and bad fats, so it can cause the body to block fats it actually needs. Essential fatty acids found in olive oil, nuts, avocados, fish and elsewhere that help to promote health and are actually essential to many processes in our bodies are blocked along with the fat from the cheeseburger and fries. 

Human chorionic gonadotropin

Another trendy medication out there works great as long as you combine it with a diet restricted to 500 to 800 calories a day. Human chorionic gonadotropin (HCG) is available as a shot, pill or sublingual drops. Guess what? Anyone who eats 500 to 800 calories a day will lose weight! Proponents will tell you that HCG enhances weight loss over placebo because it suppresses appetite and targets the deep fat stores in the body. To date, no credible scientific studies exist to substantiate this claim. 

So if we assume that HCG is no different than placebo, and we see that people are getting results, you may wonder “where is the danger in taking it?” While HCG poses no inherent risks, the real hazard lies in the extreme caloric restriction that’s part of the diet. When you reduce your calories to very low levels, your body acts as if it is starving. It then decreases the amount of energy that it spends to perform normal functions. It burns fewer calories and becomes more efficient at holding on to energy (fat) because it doesn’t know when it will get refueled. 

No magic bullet

When it comes to weight loss, pills are no substitute for eating healthily and exercising. Notice I said “eating healthily,” and not “dieting.” The word “diet” conjures feelings of deprivation and sacrifice for many people. Others think of a diet as something to do until their weight loss goal is achieved, and then they go back to their normal way of eating. They see diet pills as an easier answer to their weight problem, and if their doctor gives it to them it must be safe and effective, right? Wrong. All medications have side effects and long-term risks. Why assume those risks when you can lose weight and keep it off the healthy way?