Weight loss pills are taken as tools to help overweight and obese individuals reach a healthy weight.
Obesity affects approximately 39 percent of adults in the US, making it a widespread concern. Several medical associations, including the American Medical Association (AMA), the American Association of Clinical Endocrinologists and the National Institutes of Health (NIH) have officially recognized obesity as a chronic disease.
The risk of complications from being overweight or obese are many, and include heart disease, stroke, type 2 diabetes and certain types of cancer (1).
When diet and exercise fail to help obese individuals achieve adequate results — especially those who have a serious medical problem related to obesity (such as high blood pressure or heart disease) — a prescription weight-loss pill may be a helpful option.
Doctors stress the importance of knowing the difference between weight loss supplements and prescription weight loss pills.
Although there are many diet supplements available over-the-counter, there is little research on these products and they are not regulated by the FDA. Some supplements even carry the potential for causing serious adverse effects.
Unlike supplements, prescription weight loss drugs have been approved by the FDA.
There are currently five weight loss medications that have been approved by the FDA for long-term use: bupropion-naltrexone (Contrave), liraglutide (Saxenda), lorcaserin (Belviq), orlistat (Xenical) and phentermine-topiramate (Qsymia).
1 Weight loss pills reduce appetite. Appetite suppressants are believed to work on two areas of the brain—the hypothalamus (the hunger center) to help reduce hunger and the mesolimbic reward system to help control cravings — which sabotage the efforts of those trying to lose weight.
The drug Contrave, is an example of an appetite suppressant. It contains two drugs: Naltrexone, which is an anti-addiction medication approved to treat alcohol and opioid dependence, and Bupropion, which is approved to treat depression and seasonal affective disorder and is an aid to smoking cessation treatment.
When these two drugs are used together, there is a synergistic weight loss effect.
Essentially, appetite suppressants act upon the body’s central nervous system, tricking the body into believing that it is not hungry. It may be particularly effective in people who have food addictions.
Three long-term (56 weeks) studies have shown that patients who add Contrave to their diet and exercise regimen lose approximately 2 to 4 times more weight than with diet and exercise alone.
In another study, patients who also participated in an intensive diet and exercise program and remained on Contrave for a full year, lost 25 pounds on average (2).
2 Weight loss pills block the absorption of fat. Normally, fat from a diet is broken down into smaller particles by enzymes in the digestive tract, so that it can be absorbed into the body. The weight loss pill Xenical, interferes with the work of enzymes, to stop about 30 percent of the fat from being digested.
This undigested fat passes out of the body naturally, so individuals absorb fewer calories from what they eat.
Xenical only works in the digestive system, so to get the best results, individuals need to do their part by eating a healthy diet and exercising.
In several trials lasting up to two years, Xenical was more effective than diet alone for weight reduction and maintenance of lost weight.
In a 2011 evaluation of the efficacy and safety of this drug in 80 obese patients, Xenical caused significant reduction in weight, body mass index (a measure of body fat based on height and weight) and waist circumference compared to placebo (3).
3 Weight loss pills trigger the feeling of being full. The weight loss medication, Belviq belongs to a class of medications called serotonin receptor agonists. Serotonin is an important chemical and neurotransmitter that is primarily known for its role in regulating mood. It also triggers feelings of satiety and satisfaction when eating.
Just as serotonin naturally turns on receptors to cause feelings of fullness, Belviq is believed to selectively turn on these “fullness receptors,” helping individuals feel full while eating less food (4).
The results of two major clinical trials showed that 47 percent of adults taking Belviq lost 5 percent or more of their body weight during the first year, compared with those using diet and exercise alone (22 percent).
4 Weight loss pills may help treat binge eating disorder. Binge eating disorder (BED) is an eating disorder characterized by recurrent episodes of eating large quantities of food. In their studies on the effects of the drug Qsymia on weight loss, researchers found that the drug may also help treat BED.
In a placebo-controlled study of obese individuals with BED, topiramate (one of the components of Qsymia) reduced binge-eating episodes compared to placebo, and induced binge eating remission in 58 percent of the patients (5).
5 Weight loss pills may benefit those with type 2 diabetes. Type 2 diabetes is a chronic condition that affects the way the body metabolizes sugar (glucose) — an important source of fuel for the body. Complications of this condition include heart and blood vessel disease, nerve damage and kidney damage.
In addition to causing weight loss, studies show that Belviq can lower blood sugar levels and possibly, blood pressure and LDL (“bad”) cholesterol levels. By lowering blood sugar levels, Belviq reduces the risk of diabetes among prediabetic patients, and for people with diabetes, it helps lower Hb-A1c levels.
For people with diabetes this is important as the higher the HbA1c, the greater the risk of developing diabetes-related complications (6).
6 Weight loss pills provide cardiovascular benefits, due to weight loss. On average, people taking prescription weight-loss medications lose about 5 to 10 percent of their starting weight over the course of one year (or about 10 to 20 pounds for someone weighing 200 pounds).
While this amount of weight loss seems small, studies show it is enough to make a big impact on improving heart health (7).
In a 2011 study evaluating the efficacy and safety of Xenical in obese patients, researchers noted a reduction in low-density lipoprotein, or LDL cholesterol (8).
Losing 5-10 percent of body weight has also been shown to decrease triglycerides by an average of 40 mg/dl, and blood pressure by 5 mmHg.
7 Weight loss from weight loss pills may improve obstructive sleep apnea, due to weight loss. Obstructive sleep apnea is a sleep disorder that causes breathing to repeatedly stop and start during sleep. It occurs when the throat muscles intermittently relax and block the airway during sleep.
People who are overweight are more likely to have fat deposits around the upper airway which may obstruct breathing.
It has been shown that losing just 10 percent of body weight may improve sleep apnea, and in some cases, losing a significant amount of weight can even cure the condition (9).
8 Weight loss pills can help reduce inflammation, due to weight loss. Fat cells, especially those around the abdominal area produce substances that can cause inflammation in blood vessels. This inflammation is linked to several health problems such as arthritis, heart disease, heart attack and stroke.
Losing 10 percent body weight can lower the amount of these substances and cut the chances of health complications.
Side effects vary by the type of medication and how it acts on the body.
The most common side effects include gastrointestinal issues (nausea, vomiting, diarrhea, oily stools, constipation, flatulence and stomach pain). Most side effects are mild and most often improve with regular use.
Other possible side effects include headache, low blood sugar, back pain, dry mouth and tiredness. Some medications can cause serious side effects, including:
1 Weight loss pills may cause suicidal thoughts. One of the ingredients in Contrave — bupropion — may increase the risk of suicidal thoughts in children, adolescents and young adults. Patients prescribed this drug should be monitored for suicidal thoughts and behaviors. It is not approved for use in children under the age of 18 (10).
Topiramate, an ingredient in Qsymia, may also cause suicidal thoughts or actions (11).
2 Weight loss pills may raise blood pressure. Hypertension (high blood pressure) has been reported in some prescribed Contrave. Regular monitoring of blood pressure is necessary, especially at the start of treatment.
3 Weight loss pills may cause mood changes and insomnia. Depression or mood problems, and trouble sleeping may occur when taking Qsymia.
4 Weight loss pills may cause concentration, memory and speech difficulties. Qsymia may affect how some think and cause confusion, problems with concentration, attention, memory or speech.
5 Weight loss pills may cause seizures. There is a risk of having a seizure when taking Contrave; those who have or have had seizures should not take this drug.
6 Weight loss pills can cause birth defects. Qsymia has been linked to certain birth defects such as cleft lip or cleft palate.
Prescription weight loss medications can also interact with certain other medications and may not be suitable for individuals with certain medical conditions.
Contrave, for example, may affect the way other medications work, especially opioid medicines or medicines to help stop taking opioids.
Recommended dosages vary depending on the specific drug prescribed.
Contrave should be taken by mouth in the morning and in the evening and should not be taken with high-fat meals. According to the manufacturer, this is because of a resulting significant increase in bupropion and naltrexone systemic exposure.
The dose of Contrave is slowly increased over time to help patients adjust to their medication. A total daily dosage of four Contrave tablets (two tablets taken twice per day) should be reached at the start of week four.
Saxenda is the only one of the five FDA-approved drugs that is injected rather than taken orally. It is injected under the skin in the abdomen, thigh or upper arm. The recommended dose is 3 mg daily (12).
The recommended dosage of Belviq is 10 mg taken orally twice daily.
The recommended dose of Xenical is one 120-mg capsule three times a day with each main meal containing fat (during or up to 1 hour after the meal). Xenical works by blocking fat, so if there is no fat in the meal, it will have no effect.
The average dose of Qsymia (phentermine-topiramate) is 7.5 mg of phentermine and 46 mg of topiramate once a day. Avoid taking this medicine in the evening to prevent insomnia.
Weight loss medications are meant to be taken long-term. Individuals who have lost enough weight to improve their health and are not experiencing serious side effects, will likely be advised to stay on the medication indefinitely.
If individuals do not lose at least 5 percent of their starting weight after 12 weeks on the full dose of their medication, their doctor will likely change their treatment plan or consider using a different weight-loss medication.
What is the best weight loss pill? There are several scientifically-back prescription weight loss pills available. Choosing the one that is best is a decision that needs to be made between you and your doctor. Your doctor will take into consideration your current health issues, health history and the medication’s side effects.
What is the best over-the-counter weight loss supplement? Dietary supplement manufacturers do not need FDA approval prior to marketing their products, therefore, their efficacy and safety are not always fully understood. Until further studies are performed on these supplements, healthcare providers generally hesitate to recommend them.
There is one exception, however. Alli is the only FDA-approved weight loss medication available over-the-counter. It is a milder form of the prescription Xenical.
Before taking any over-the-counter supplement for weight loss, it is best to talk with a doctor or other healthcare professional.
What weight loss pill is approved by the FDA? There are five medications that have been approved by the FDA for use: bupropion-naltrexone (Contrave), liraglutide (Saxenda), lorcaserin (Belviq), orlistat (Xenical) and phentermine-topiramate (Qsymia).
What is the safest weight loss pill? Although all five prescription weight loss pills come with the risk of side effects, most of them are mild and include diarrhea, gas, nausea, constipation, dry mouth and dizziness.
Belviq is among the best weight loss pills when it comes to safety. Individual results vary, however, and some carry the risk of more serious adverse effects.
The ingredient phentermine — a component of Qsymia — is not usually recommended for people who have high blood pressure or other heart conditions.
Topiramate, another component of Qsymia, has been linked to an increased risk of birth defects, so women who are planning to get pregnant should avoid this medication.
Who might benefit from weight loss pills? Adults who have not been able to achieve significant weight loss with diet and exercise and have a body mass index (BMI) of 30 or more (considered obese), or a BMI of 27 or more (considered overweight) who have weight-related health problems (such as high blood pressure or type 2 diabetes), might benefit from weight loss pills.
How much weight can I lose? Over one year, patients using weight loss drugs may lose roughly 5 percent to 10 percent of their initial weight when used as part of a diet and exercise plan.
Can children or teenagers take weight loss medications? The FDA has approved most weight-loss medications only for adults. The prescription medication Xenical is FDA-approved for children ages 12 and older.
What is the difference between weight loss supplements and prescription weight loss drugs? The manufacturers of dietary supplements are responsible for ensuring the safety of their product and making honest claims about possible benefits. However, the manufacturers’ claims are not subject to FDA review or approval before marketing.
When safety issues are suspected, however, FDA must investigate and, when warranted, take steps to have these products removed from the market.
Prescription weight loss pills are approved by the FDA. This means experts reviewed the results of laboratory, animal and human clinical testing done by manufacturers. If FDA grants an approval, it means the agency has determined that the benefits of the product outweigh the known risks for the intended use.
Are over-the-counter supplements effective for weight loss? Although some of the individual ingredients in over-the-counter supplements may aid in weight loss, the research is lacking and often inconsistent.
For example, a synthetic version of raspberry ketones (a substance found in raspberries which give it its smell) is sold as a weight loss supplement. Unfortunately, the one clinical trial performed on this supplement lasted only eight weeks, which is not long enough to know if the supplement will help with weight loss long term.
Also, the supplement included multiple ingredients, making it impossible to judge which ingredients helped the weight loss.
Medical experts also warn that a product is not necessarily safe simply because it is natural.
Can medications replace physical activity and healthy eating habits as a way to lose weight? No. Studies show that weight loss medications work best when combined with healthy eating habits and regular exercise.
What supplement will help me lose weight fast? The FDA repeatedly warns consumers against taking products that claim to be weight-loss “miracles” or make promises of a quick fix, for example, “lose 10 pounds in one week.” Weight loss takes time and there is no “magic pill” that will help burn or melt fat away.
How do these drugs help with weight loss? Most prescription weight-loss drugs work by decreasing appetite or increasing feelings of fullness, and some do both. The exception is Xenical, which works by interfering with absorption of fat.
How long does drug therapy last? How long you will need to take weight-loss medication depends on whether the drug helps you lose weight and whether you have any side effects. If you have lost enough weight to improve your health and are not having serious side effects, your doctor may suggest that you stay on the medication indefinitely.
If you do not lose at least 5 percent of your body weight after 12 weeks on the full dose of your medication, your doctor will probably change your treatment plan or consider using a different weight-loss medication.
After stopping weight-loss medication, many people gain back some of the weight they lost. However, adopting healthy lifestyle habits may help limit weight gain.
Will insurance cover the cost of weight-loss medication? Some, but not all, insurance plans cover medications that treat overweight and obesity. Contact your insurance provider to find out if your plan covers these medications.
What weight loss medications may be available in the future? Researchers are working to identify safer and more effective medications to help people who are overweight or obese. According to the National Institute of Diabetes and Digestive and Kidney Diseases, researchers are focusing on drugs that stimulate gut hormones that reduce appetite, shrink the blood vessels that feed fat cells in the body and target genes that affect body weight (13).
Weigh loss pills are prescribed to overweight and obese individuals — especially those who have a serious medical problem related to obesity (such as high blood pressure or heart disease) — to help them reach a healthy weight.
There are currently five weight loss drugs that are approved by the FDA: Contrave, Saxenda, Belviq, Xenical and Qsymia.
Most prescription weight-loss drugs work by decreasing appetite or increasing feelings of fullness, and some do both. The exception is Xenical, which works by interfering with absorption of fat.
Weight-loss drugs are not an easy answer to weight loss. Studies show that weight loss medications work best when combined with physical activity and healthy eating habits. These drugs are approved for long-term use.
Minor side effects may include gastrointestinal issues (nausea, vomiting, diarrhea, oily stools, constipation, flatulence and stomach pain) and dry mouth.
Some have been linked to serious safety concerns: Contrave may increase suicidal thoughts and Qsymia may cause birth defects.
Prescription weight loss medications can interact with certain other medications and may not be suitable for individuals with certain medical conditions.