Many people choose weight loss as their new year resolution. In addition to the usual steps to achieving weight loss – setting specific and measurable goals, eating healthy, exercising, and other lifestyle changes – some people also use weight loss medicines or supplements. It is essential to discuss your plans to use these with your health care providers. Medicines and supplements may be helpful for weight loss for some people when used correctly. However, it is important to understand the risks and benefits before starting any weight loss medicine or supplement by talking with your health care provider.
Let’s take a closer look at both Food and Drug Administration (FDA)-approved weight loss medicines and non-FDA approved weight loss supplements.
Currently, there are six FDA-approved medicines for weight loss in people who are obese (body mass index (BMI) over 30) or overweight (BMI from 25.0 to 29.9) with co-morbidities (two or more diseases/medical conditions occurring at the same time). They are:
Liraglutide (Saxenda) and Semaglutide (Wegovy)
These injectable medicines mimic a hormone that can help curb appetite and calorie intake, making the person feel fuller sooner. Studies looking at these medicines show they can be effective in helping people lose weight and keep the weight off for 1-2 years. Lifestyle changes and exercise, in addition to the medicines, were part of weight loss plans.
Both liraglutide and semaglutide can be taken long-term. Common side effects include nausea, vomiting, diarrhea, heart rate increase, and low blood sugar when using insulin. Rare side effects include thyroid C-cell tumors and acute pancreatitis.
Naltrexone HCl and Bupropion (Contrave) Extended-Release
Naltrexone has been used for alcohol and opioid dependence, while bupropion has been used for depression and smoking cessation. This combination is thought to work in the brain to increase neuron activity at the appetite regulator center and the rewards system, promoting fullness and reducing food intake. Studies have shown that taking naltrexone-bupropion in addition to lifestyle changes is more effective than making lifestyle changes only.
This medicine is approved for long-term use. Common side effects include nausea, constipation, and headache. Taking it may increase blood pressure and heart rate. It is recommended to avoid high-fat meals while taking it. You should not take bupropion-naltrexone if you have seizures or take opioid pain medicines. Your provider may recommend you stop taking the medicine if you do not see measurable weight loss after 12 weeks.
Phentermine (Adipex-P, Lomaira) and Phentermine-Topiramate (Qsymia)
Phentermine is an amphetamine, which is a type of stimulant. Phentermine is thought to curb appetite to reduce food intake by changing how a neurotransmitter is released in the brain. Topiramate is a medicine sometimes used for seizure control or migraine headaches. Phentermine-topiramate contains a smaller dose of phentermine than phentermine alone. These medicines are thought to curb appetite and make one feel fuller by increasing neurotransmission activity in the brain.
Phentermine is approved for short-term use (less than 12 weeks) only, as successful studies have shown. Do not take this medicine in the evening or at night because it may cause sleeplessness (staying awake). Do not take if you have a history of heart disease, heart failure, uncontrolled high blood pressure, glaucoma, hyperthyroidism, or if you are pregnant or nursing.
Orlistat (Xenical) and Over-the-Counter Alli
Orlistat works by stopping your body from absorbing a portion of fat in the food that you eat. Xenical is sold as a prescription and can absorb about 30% of the fat you eat. Studies showed after one year of use with lifestyle changes, more patients were able to achieve weight loss than those who only did a diet alone.
Alli is sold as an over-the-counter supplement because it is a half dose of the prescribed medicine Xenical. Alli can absorb about 25% of the fat you eat.
The most common side effects of these medicines are oily stools, passing gas, and the inability to control bowel movements. These effects may increase when eating a high-fat diet. Liver injury has also been reported when taking orlistat. Because orlistat can affect the absorption of fat-soluble vitamins from food, all patients should take a daily multivitamin that contains vitamins A, D, E, K, and beta-carotene at least two hours before or after taking the medicine. Do not take orlistat if you’re pregnant.
Setmelanotide is an injectable medicine approved for adults and children six years and older with obesity due to specific medical conditions. Setmelanotide is thought to increase metabolism and help regulate appetite and fullness. Studies showed that some patients were able to achieve at least 10% weight loss after one year. In general, people feel less hungry when taking this medicine. Common side effects include injection site reactions, skin darkening, nausea, headache, abdominal pain, back pain, and spontaneous penile erection in men. Depression and suicidal thoughts have also occurred. Your provider may recommend you stop taking the medicine if you have not lost weight after taking it for 3-4 months.
Non-FDA Approved Supplements
Many supplements are advertised for their potential for weight loss. However, the FDA does not regulate supplements as drugs. As a result, supplements often lack quality medical trials to prove to be safe and beneficial. In addition, some supplements in the market were found to be tainted, meaning they contained ingredients that did not appear on the product label. For the most updated list, visit the FDA’s Tainted Weight Loss Products page. Nevertheless, some supplements are certified by third-party companies and are tested for listed ingredients and harmful levels of certain contaminants. Examples of certification companies include NSF, USP, BSCG, and ConsumerLab.
The following is a partial list of weight loss supplements and what we know about them:
- Chitosan– A polysaccharide extract that reduces how much fat and cholesterol the body absorbs. A newer study shows there is only a small effect on weight loss.
- Chromium picolinate– A form of the mineral, chromium. It is thought to enhance the effects of insulin, increase glucose metabolism, and increase muscle mass. A study done with varying doses of chromium picolinate (200 mcg – 1,000 mcg per day) found an average weight loss of 2.2 pounds. The safety of chromium picolinate is not fully understood.
- Conjugated linoleic acid– A fatty acid that may help reduce fat mass and increase fat-free mass in the body. However, studies show mixed weight loss results.
- Ephedra– Also known as ma huang, ephedra contains the stimulant ephedrine. Since 2004, the FDA has banned supplements with ephedra due to the risk of heart attack, stroke, psychiatric episodes, seizure, and death.
- Green tea– Made from the leaves of the Camellia sinensis plant, green tea, or its extract, is thought to increase energy consumption and burn fat. It has not shown to be effective for weight loss. Drinking green tea in moderation is usually safe. However, green tea extracts are more concentrated and can possibly cause liver injury when used alone or with other supplements.
- Hoodia Gordonii– A member of the milkweed family. One of its components, P57, is thought to curb appetite. Limited studies are available.
- Human chorionic gonadotropin (hCG)– hCG injection is mainly used for fertility treatment. An oral form of hCG, combined with a very-low-calorie diet, has been advertised for weight loss. People who follow the plan may see weight loss for a short term, possibly due to the low-calorie diet. However, the safety and benefit of hCG for weight loss is unknown. Side effects of hCG include irritability, restlessness, and blood clots.
- Hydroxycitric acid– Extracted from the rind of the fruit Garcinia Cambogia. It is thought to promote fullness and curb appetite. Weight loss results are mixed, and studies have not shown positive results.
Before you start any medicines or supplements for weight loss, make sure to talk with your health care providers to review for medical conditions and drug interactions. Tell your provider if you’re pregnant, nursing, or planning to become pregnant. Share a list of all of the medicines you take, both prescription and over-the-counter, supplements, and vitamins. While taking medicines and supplements, talk to your health care provider if you experience any side effects. If you experience life-threatening symptoms (e.g., loss of consciousness or trouble breathing), call 911 right away.
Similar to any other medicines and supplements, it is important to use and store weight loss medicines safely. Always read and follow the directions on the label as they are written. Do not take more than directed. Medicines should be closed tightly before being stored, away and out of sight.
Call your local poison center to speak with a poison expert if you think a weight loss product was taken in the wrong amount or by the wrong person. Do not wait for symptoms to call. Poison specialists can be reached 24 hours a day, seven days a week at 1-800-222-1222.
Clinical Toxicology Fellow