Medications used for weight loss

Medication may be helpful for weight loss when used in combination with diet, exercise, and lifestyle changes. However, it is important to understand the risks, benefits, and limitations of these medicines. They can cause side effects that may be bothersome, and in many cases the long-term safety data are limited. In addition, these medicines may not be covered by insurance and can be expensive. Although weight loss medicines may not help you reach your "dream" weight, they can contribute to reducing your risk of diabetes or heart disease.

Weight loss medicines may be recommended for people who have not been able to lose weight with diet and exercise who have a:

●Body mass index (BMI) of 30 or more (calculator 1 and calculator 2)

●BMI between 27 and 29.9 and have other medical problems, such as diabetes, high cholesterol, or high blood pressure

Some of the available weight loss medications are discussed below. Your doctor can talk to you about the different medications and your options based on your situation, medical history, and preferences. If you try a medicine for weight loss and it does not work or you are bothered by side effects, your doctor may suggest trying a different medicine or combination of medicines.

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GLP-1 receptor agonists — Glucagon-like peptide 1 (GLP-1) receptor agonists are medications given by injection under the skin in the abdomen, thigh, or upper arm. They are used in the treatment of diabetes; they work by increasing insulin release in response to a meal and slowing digestion. They may also have cardiovascular benefits in adults with type 2 diabetes.

In the United States, the GLP-1 receptor agonists liraglutide and semaglutide are also approved for the treatment of obesity in people without diabetes. Liraglutide (brand name: Saxenda) is injected once daily, while semaglutide (brand name: Wegovy) is injected once weekly. Both medications are started at a low dose then increased gradually to help minimize side effects such as nausea.

Liraglutide and semaglutide are very effective weight loss medications. In studies evaluating the use of these medications along with lifestyle changes, people lost up to 7 to 16 percent of their body weight when taken for one year or longer; semaglutide appears to induce greater weight loss than liraglutide.

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Side effects of GLP-1 receptor agonists are common, particularly at higher doses, and may include nausea, vomiting, or diarrhea. You may not be able to tolerate the recommended dose of the medication due to side effects, but your health care provider may recommend continuing to take it at a lower dose if you are losing weight.

GLP-1 receptor agonists should not be taken during pregnancy and if you have a history of pancreatitis or a personal or family history of medullary thyroid cancer or a disorder called multiple endocrine neoplasia. If you have diabetes and take other medications to help control your blood sugar, your provider will want to monitor your blood sugar closely and may reduce the dose of your other diabetes medications while you are taking the GLP-1 agonist. 

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Orlistat — Orlistat (brand name: Xenical) is a medicine that reduces the amount of fat your body absorbs from the foods you eat. A lower-dose version (brand name: Alli) is available without a prescription in many countries, including the United States. The recommended dose of the prescription version is one capsule three times per day, taken with a meal; you can skip a dose if you skip a meal or if the meal contains no fat.

After one year of treatment with orlistat combined with lifestyle changes, the average weight loss is approximately 8 to 10 percent of initial body weight. Cholesterol levels often improve and blood pressure sometimes falls. In people with diabetes, orlistat may help control blood sugar levels.

Side effects may include stomach cramps, gas, diarrhea, leakage of stool, or oily stools. These problems are more likely when you take orlistat with a high-fat meal (if more than 30 percent of calories in the meal are from fat). Side effects usually improve as you learn to avoid high-fat foods. Severe liver injury has been reported rarely in people taking orlistat, but it is not known if orlistat caused the liver problems.

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Phentermine — Phentermine (brand names: Adipex-P, Lomaira) is a medicine that reduces food intake by causing you to feel full more quickly after eating. Phentermine is classified as a controlled substance by the United States (US) Food and Drug Administration due to its potential for abuse, although the actual observed rate of abuse is extremely low; it is the most widely prescribed single agent weight loss drug in the US.

In trials ranging from 12 to 36 weeks, patients taking phentermine lost an average of approximately 15 to 17 pounds (7 to 8 kg). Phentermine may cause an increase in blood pressure and heart rate; your health care provider will monitor you for these side effects while you are taking the medication. In addition, phentermine may cause insomnia, dry mouth, constipation and nervousness. You should not take phentermine if you have heart disease, uncontrolled high blood pressure, hyperthyroidism, or a history of drug abuse.

Phentermine is taken once or twice daily, and is intended for short-term use (<12 weeks). If you do not lose at least 5 percent of your initial body weight after 12 weeks, you should stop the medication and talk with your health care provider about other options.

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Phentermine-topiramate — Phentermine and extended-release topiramate are available in combination as a single capsule (brand name: Qsymia). Topiramate is used for the prevention of migraine headaches and to treat seizures in people with epilepsy. People taking topiramate for these indications lose weight, but the way this works is uncertain. People taking this combination medication lose approximately 8 to 10 percent of their initial body weight after one year.

The dose of phentermine-topiramate is usually increased gradually, while weight loss is monitored. If you do not lose 5 percent of your initial body weight after 12 weeks on the highest dose, phentermine-topiramate should be discontinued gradually, as abrupt withdrawal of topiramate can cause seizures.

The most common side events are dry mouth, constipation, and a "pins and needles" sensation of the skin. There is also a risk of psychiatric (eg, depression, anxiety) and cognitive (eg, disturbance in attention) problems; this risk increases with larger doses of the medication. Although phentermine-topiramate improves blood pressure slightly, it is also associated with an increase in heart rate.

Phentermine-topiramate should not be used during pregnancy because of the risk of birth defects. People who could get pregnant should take a pregnancy test before starting this medication (and monthly thereafter) to ensure that they are not pregnant. It should also not be used in people with cardiovascular disease (high blood pressure or coronary heart disease).

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Bupropion-naltrexone — Bupropion is a medicine that is used to treat depression and to prevent weight gain in people who are trying to quit smoking. Naltrexone is a drug used to treat alcohol and drug dependence. People taking combination bupropion-naltrexone (brand name: Contrave) lost approximately 5 to 6 percent of their initial body weight after one year. Common side effects include nausea, headache, constipation, insomnia, vomiting, dizziness, and dry mouth. The dose of bupropion-naltrexone is increased gradually over four weeks. If you do not lose at least 5 percent of your initial body weight after 12 weeks, the medication should be discontinued because benefit is unlikely.

Bupropion-naltrexone should not be used in people with uncontrolled high blood pressure, a seizure disorder, or an eating disorder. It should also not be used by people who take (or have recently taken) certain other medications, including those containing bupropion, chronic opioids, or monamine oxidase inhibitors.

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DIETARY SUPPLEMENTS NOT RECOMMENDED

Dietary supplements are widely used by people who are trying to lose weight. However, doctors do not recommend their use because some are unsafe, and other supplements have not been studied carefully and there is no proof that they are safe or effective.

You may have heard of some of the following dietary supplements, which are often advertised for weight loss. 

None of these are recommended:

●Ephedra, a compound related to ephedrine, is no longer available in the United States due to safety concerns. Many nonprescription diet pills previously contained ephedra. Although some studies have shown that ephedra helps with weight loss, there can be serious side effects (psychiatric symptoms, palpitations, and stomach upset), including death.

●Two supplements from Brazil, Emagrece Sim (also known as the Brazilian diet pill) and Herbathin dietary supplement, have been shown to contain prescription drugs and should be avoided.

●Bitter orange (Citrus aurantium) can increase your heart rate and blood pressure and is not recommended.

●There are not enough data about safety and efficacy to recommend chitosan, chromium, green tea, Hoodia gordonii, hydroxycitric acid, or conjugated linoleic acid.

●Human chorionic gonadotropin (hCG) is a hormonal preparation, usually given by injection, that has been advertised as a weight loss aid when combined with a very-low-calorie diet. There have been several studies showing that hCG is no more effective than placebo; thus, it is not recommended.

WEIGHT LOSS PROCEDURESBariatric (weight loss) surgery may be an option in certain situations, if a person is not able to lose weight with lifestyle changes and medications. There are different types of bariatric surgery. More detailed information on weight loss procedures is available separately.

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