Obesity Medication

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Facts on Obesity Medication

  • Obesity means accumulation of excess body fat. Obesity is considered a chronic (long-term) disease, similar to high blood pressure or diabetes.
  • As such, it usually requires long-term treatment to successfully lose weight and keep it off.
  • Obesity has many serious long-term consequences for your health, and it is the second leading cause of preventable deaths in the United States. (Tobacco is the first).
  • Obesity is an epidemic in the United States and in other developed countries.
  • Two-thirds of Americans are overweight. Nearly one-third are obese. Obesity is on the rise in our society because food is abundant and physical activity is typically an option rather than linked to our daily activities and jobs.

What Are the Health Risks of Obesity?

Obesity is defined as a body mass index (BMI) of 30 or higher. Body mass index is easily calculated from your weight and height (see body mass index calculator). What does BMI mean?

  • Generally, a BMI of 18.5 to 25 is considered healthy.
  • A BMI of 25 to 30 is considered overweight.
  • A BMI of 30 to 40 is considered obese.
  • A BMI of 40 and over is considered morbidly (severely) obese.

The health problems associated with obesity may contribute to poor quality of life, disability, and even premature death. Your body mass index is a good predictor of whether you will develop obesity-related health problems, such as the following:

Weight Loss: Top 10 Habits That Can Help You Lose Weight

What Is the Treatment of Obesity?


The safest and most effective way to lose weight is a combination of eating less and increasing physical activity.

  • While there are many different methods for decreasing the amount of food you eat, the successful ones all have one thing in common: reducing calorie intake.

Physical activity

Physical activity helps you lose weight by burning calories.

  • It also may help you keep weight off once you lose it.
  • Many obese people think they cannot exercise, but everyday physical activities such as walking, climbing stairs, doing chores, and dancing can help you lose weight if done daily for at least 30 minutes.

Behavior modification

This is another name for changing your attitude toward food and exercise.

  • These changes promote new habits and attitudes that help you lose weight.
  • Many people find they cannot lose weight or keep it off unless they change these attitudes.
  • Behavioral-modification techniques are easy to learn and practice.
  • Most involve increasing your awareness of situations in which you overeat so that you can stop overeating.
  • Support groups are one form of behavioral therapy.


Some obese people have difficulty losing weight through diet and exercise alone.

  • If that is the case with you, see your health care professional. He or she may be able to suggest some new strategies that you haven't tried.
  • In some, but not all cases, your health care professional may suggest additional treatments to help you lose weight. Medication is by far the most widely used of these treatments.


Surgery for obesity, called bariatric surgery, alters the stomach or the intestines so that the person digests less food or is satisfied with less food.

  • These operations have improved over the years and are now considered a safe and acceptable way to help obese people control their weight.
  • However, all operations have risks, and for that reason, surgery is recommended only for morbidly obese people (BMI greater than 40), or obese people (BMI greater than 35) if the person has serious obesity-related medical problems).
  • Like all treatment for obesity, surgery is successful only if the person is committed to lifestyle changes and has a desire for better health.


Many dietary supplements make promises about weight loss. In fact, few if any of these have been shown to definitely help with weight loss.

  • In general, people who have lost weight while taking these supplements also have eaten less and increased their physical activity.
  • However, some of these are being studied to see whether they are safe and effective.

How Can Medication Help You Lose Weight?

With one exception, the medications used to treat obesity work by suppressing the appetite.

  • Appetite suppressants decrease appetite by increasing levels of serotonin or catecholamines, such as norepinephrine. Serotonin and catecholamines are brain chemicals that affect mood and appetite.
  • The exception, Xenical, works by disrupting lipase, the enzyme in the intestines that controls absorption of fats. It prevents digestion of about 30% of the fats eaten. These undigested fats are not absorbed, but excreted, thus lowering the calorie intake.

These medications work best if used in conjunction with lifestyle changes such as eating less and increasing physical activity. Research studies conducted in people with obesity all show that people who eat less, increase physical activity, and take medication lose considerably more weight than people who use medication without making lifestyle changes.

Like all drugs, those used to treat obesity may have powerful side effects and other undesirable risks.

  • Prescription weight-loss medications should be used only under the care of a medical professional and only by people who are at high risk of obesity-related health problems.
  • This usually means people with a BMI of 30 or greater or those with a BMI of 27 or greater who have other risk factors such as high blood pressure or high cholesterol.
  • These medications should not be used for relatively minor or cosmetic weight loss.

Some physicians have experimented with combining weight-loss drugs.

  • Some have combined a weight-loss drug with another type of drug such as a selective serotonin-reuptake inhibitor (SSRI), a class of antidepressants that includes fluoxetine (Prozac) and sertraline (Zoloft).
  • This is called "off label" use because these combinations have not been approved by the U.S. Food and Drug Administration (FDA) for obesity.
  • Little information is available about the safety or effectiveness of these combinations.

Traditional weight-loss medications were approved for only a few weeks or months of use. The newer medications now in use may be used for longer periods. These drugs are still being studied to see whether they have any long-term side effects.

What Are the Risks and Benefits of Weight-Loss Medications?

The possible benefits of these drugs in the short term include weight loss, which may lower the risk of some obesity-related health problems. Whether these drugs actually improve a person's health over the long term is not known.

The risks include the side effects, which vary from drug to drug (see next section).

  • Side effects are especially a concern in patients who may be healthy other than their obesity.
  • Other concerns include the potential for abuse of the drugs (all except Xenical are controlled substances).
  • People taking these drugs often find that their weight loss tapers off after four to six months. This is usually attributed to development of tolerance, in other words that the medication has reached its limit of effectiveness. The drugs are being studied to see if tolerance really does occur.

To ensure your safety, before you start taking one of these drugs, be sure to let your health care professional know if you have any of the following medical conditions:

What Medications Are Used in the Treatment of Obesity?

These medications have been approved by the U.S. Food and Drug Administration (FDA) for the treatment of obesity. They are available in the United States only by prescription. Ask your health care professional about these medications.

Sibutramine (Meridia) is a prescription medication approved by the FDA in 1996. It may be recommended for people who are more than 30 pounds overweight. Unlike phentermine, sibutramine is a nonamphetamine appetite suppressant that may also have antidepressant properties.

  • This drug may increase blood pressure, so regular monitoring is essential.
  • It affects levels of two brain chemicals, serotonin and norepinephrine, which control mood and appetite.
  • In clinical trials, the average weight loss was 5%-10% of body weight, when combined with a reduced calorie diet. It may also help to maintain weight loss.
  • Sibutramine may cause serotonin syndrome, a rare but serious condition.
  • This medication should not be used in the following instances:
    • People younger than 16 years
    • Pregnant or breastfeeding women
    • People taking an MAO inhibitor medication or an SSRI for depression (such as Prozac, Zoloft, or Paxil)
    • Anyone taking other prescription or over-the-counter diet aids
    • People taking prescription pain relievers such as Demerol, Duragesic, or Talwin

Orlistat (Xenical, Alli) is a prescription medication approved by the FDA in 1999. Your doctor may prescribe it if you weigh more than 30% over healthy body weight or have a BMI greater than 30.

  • Orlistat works in the digestive system to block the digestion of about 30% of dietary fat that you eat. The undigested fat is then eliminated in bowel movements.
  • You must adhere to a reduced-calorie diet that contains no more than 30% fat. This medication will also block digestion of the fat-soluble vitamins A, D, E, and K, so a supplement should be taken.
  • The undigested fat will cause changes in your bowel movements. They will increase in frequency and number. You may be unable to control your bowel movements. They may also be oily in consistency. These effects will be more pronounced if your meals contain more than 30% fat.
  • Over one year, people treated with orlistat in addition to a reduced fat and calorie diet lost an average of 13.4 pounds. A comparison group that used diet only without orlistat lost an average of 5.8 pounds.
  • This medication should not be used in the following instances:
    • People with chronic problems absorbing food
    • Anyone with gallbladder problems
    • Pregnant or breastfeeding women
  • Lorcaserin (Belviq 10 mg one to two times daily) was just approved by the FDA in June 2012. It may be considered if your BMI is 30 or greater or if you have a BMI greater than 27 with weight-related conditions. Studies demonstrated that almost half of patients lost an average of 5% of their body weight when combined with diet and exercise (compared to 25% of patients with diet and exercise alone). Lorcaserin works by activating the serotonin 2C receptor in the brain, which helps you feel full after smaller portions. The most common side effects were headache, nausea, and dizziness.
  • Qsymia (combination of phentermine and topiramate) was just approved by the FDA in July 2012. It is only approved for those with a BMI greater than 27 with weight-related conditions. When combined with diet and exercise, studies have shown that half of the participants lost 10% of their body weight and four-fifths lost 5% (which equates to 12 pounds in a 227-pound person). Topiramate is associated with a high risk of birth defects such as cleft lip and palate. Phenteramine (an appetite suppressant) was one of the ingredients in fen-phen and is associated with an elevation in heart rate. Because of these potentially serious side effects, Qsymia is only available through mail order. Other side effects include tingling, dizziness, alterations in taste, insomnia, dry mouth, and constipation.


Phentermine (Adipex-P, Ionamin, Fastin) is a prescription stimulant medication approved by the FDA in 1959. It is an appetite suppressant. It is approved for short-term use (a few weeks) for weight loss in addition to calorie restriction, exercise, and behavioral modification.

  • It is the phen in the fen-phen combination that was taken off the market in 1997 because of serious safety concerns. It is currently found in the recently approved medication, Qsymia as discussed above.
  • The serious heart and lung conditions caused by the combination of phentermine and fenfluramine or dexfenfluramine cannot be completely ruled out with use of phentermine alone. Although phentermine remains on the U.S. market, it has been taken off the market in Europe because of safety concerns.
  • Phentermine works by increasing the amount of the catecholamine norepinephrine in the brain. This stimulates the nervous system, suppressing appetite and possibly increasing the number of calories burned.
  • Many people taking this drug complain of palpitations (rapid heart beat), nervousness, restlessness, insomnia, shakiness, or feeling anxious.
  • This drug may give a positive result for stimulants on a urine drug test.
  • This drug has the potential for abuse. Many health care professionals are reluctant to prescribe phentermine, especially now that safer drugs are available.
  • Phentermine should not be used in the following instances:
Weight Loss: Top 10 Habits That Can Help You Lose Weight

What Obesity Medications Should I Avoid?

Some medications are not recommended for weight loss because of safety concerns. Some are no longer available in the United States. Avoid them. Be sure to check any weight-loss products you acquire without a prescription, such as through mail-order pharmacies, to make sure they do not contain any of these products.


Two drugs known as fenfluramine (Pondimin) and dexfenfluramine (Redux) affect serotonin levels in the brain.

  • These drugs, which are closely related to each other, were used in drug combinations that became very popular in the 1990s for treatment of obesity.
  • The combination was commonly referred to as fen-phen.
  • These drugs were withdrawn from the market in 1997 after they were linked to heart-valve problems and primary pulmonary hypertension. Pulmonary hypertension affects the blood vessels in the lungs and is debilitating and often fatal.

Ephedrine (ephedra, ma-huang)

A ruling by the U.S. Food and Drug Administration (FDA) on Apr. 12, 2004, prohibits dietary supplements containing ephedrine alkaloids (ephedra).

Ephedra, also called ma-huang, is a naturally occurring substance derived from plants. Its principal active ingredient is ephedrine, which, when chemically synthesized, is regulated as a drug. In recent years, ephedra products have been extensively promoted to aid weight loss, enhance sports performance, and increase energy. However, the FDA has determined that ephedra presents an unreasonable risk of illness or injury. Ephedrine has been linked to significant adverse health effects, including high blood pressure, irregular heartbeat, heart attack, stroke, and death.


Phenylpropanolamine (PPA) is a stimulant that is closely related to ephedrine. PPA was previously an ingredient in appetite suppressants as well as over-the-counter cough and cold remedies.

  • The FDA has issued a warning regarding PPA use. As a result, manufacturers removed products containing PPA from the market in October 2000.
  • Studies have suggested that this product is associated with an increased risk of hemorrhagic (bleeding) stroke in women.
Reviewed on 11/21/2017

Medically reviewed by John A. Daller, MD; American Board of Surgery with subspecialty certification in surgical critical care


Allison, D.B., et al. "Controlled-release phentermine/topiramate in severely obese adults: a randomized controlled trial (EQUIP)." Obesity. 20.2 Feb. 2012: 330-42. Epub 2011 Nov3.

Fidler, M.C., et al. "A one-year randomized trial of lorcaserin for weight loss in obese and overweight adults: the BLOSSOM trial." J Clin Endocrinol Metab. 96.10 Oct. 2011: 3067-3077. Epub 2011 Jul27.

Gadde, K.M., et al. "Effects of low-dose, controlled-release, phentermine plus topiramate combination on weight and associated comorbidities in overweight and obese adults (CONQUER): a randomized, placebo-controlled, phase 3 trial." Lancet. 377.9774 Apr. 16, 2011: 1341-1352. Epub2011 Apr8.

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Medication in the Treatment of Obesity - Effective Medications

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