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Obesity and Weight Loss Resource Center

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on June 17, 2021.

Maintaining a healthy weight is important to avoid life-threatening medical conditions and to prolong an active lifestyle. Obesity is a condition in which a person has an abnormally high and unhealthy proportion of body fat.

Staying at a healthy weight or losing weight requires a combination of regular exercise, healthy eating with portion and calorie control, and drinking low calorie fluids such as water.

You and your physician may decide that a weight loss medication is an appropriate tool in some treatment plans. Surgical weight loss, such as gastric bypass surgery, may also be the appropriate action, based upon weight and current health risks.

Excess weight is a recognized risk factor for many health problems. Complications can include:

Worldwide there are more than 650 million obese people according to the World Health Organization (WHO). In the U.S. alone, more than 42% of all adults are affected by obesity, per the CDC. Obesity-related diseases, such as heart disease, stroke, type 2 diabetes and certain cancers are among the leading causes of preventable death.

The terms “overweight” and “obese” have specific definitions in healthcare. Overweight and obese are both terms for a range of weight that are greater than what is considered healthy for a given height.1

For adults, overweight and obesity ranges are determined by using weight and height to calculate a number called the body mass index (BMI).3 BMI is used because it correlates with the amount of body fat, but it is only a screening tool and cannot assess health status and risks. BMI is also important because the use of many weight loss drugs are based on a whether a person has reached a certain BMI value.

  • An adult who has a BMI between 25 and 29.9 kg/m2 is considered overweight.
  • An adult who has a BMI of 30 kg/m2 or higher is considered obese.
  • An adult who has a BMI over 40 kg/m2 is considered severe obesity (or Class 3).

Learn More: How to Determine Your Obesity Risk Using a BMI Calculation

Other factors besides BMI are considered in determining if someone is at risk for weight-related diseases. In addition to BMI, an individual's waist circumference and other disease or lifestyle attributes, such as high blood pressure, lack of exercise, or family history are predictors of obesity-related diseases.2

What Causes Weight Gain or Obesity?

  • Food intake, portion size and calorie content: Excessive food and calorie intake, more than the body needs for energy, can be turned into fat. Foods that are high in fat and sugar can contribute to obesity. If you do not burn more calories than you burn, you will put on weight.
  • Lifestyle: A sedentary lifestyle, without adequate exercise and proper nutrition, can lead to a higher risk of becoming overweight or obese. Electronics, like computers and phones, can contribute to a sedentary lifestyle. Incorporating exercise into a daily routine can help lower the risk of weight problems. Excessive food intake, unhealthy food choices and a sedentary lifestyle ranks as one of the largest contributors to weight gain. Calories from sugar-ladened soft drinks or excessive alcohol contribute to weight issues.
  • Genetics: Genetics and family may play a role in determining your chances of being overweight or obese. Weight history can also play a role - overweight children or adolescents are more likely to be overweight in adulthood. Families also tend to share eating habits and food choices, which can contribute to weight gain.
  • Metabolic Rate: A metabolic rate, or metabolism, can differ among people with roughly the same height and weight. Someone with a low metabolic rate burns food more slowly than someone with a high metabolic rate. Someone with a low metabolic rate requires less calories to maintain a set weight than someone with a high metabolic rate.
  • Medical conditions: Some medical conditions can cause weight problems, such as Cushing's syndrome, or people with arthritis or pain, which can lead to reduced activity.
  • Drugs: Certain drugs can lead to weight gain, including:
  • Pregnancy: Many women gain weight that remains after a pregnancy. A woman should not diet or use weight-loss medications when pregnant as it can be unsafe for the developing fetus. Women should consult with their obstetrician if they are concerned about weight gain in pregnancy.
  • Other factors: Social and economic factors, age and hormonal changes, quitting smoking, lack of sleep, and stress can also contribute to weight gain.

Learn More: Which Drugs Cause Weight Gain?

Benefits to Weight Loss

Weight loss in individuals who are overweight or obese may reduce many health risks. Studies have found that weight loss with some medications may improve several health risks, such as:

  • high blood pressure, heart disease and stroke
  • high blood lipids (cholesterol, triglycerides)
  • type 2 diabetes and insulin resistance (the body’s inability to utilize blood sugar)
  • sleep apnea
  • risk of certain cancers

Latest Weight Loss Drug Approvals

Anorexiants are FDA-approved drugs that work in the brain to help suppress appetite and boost weight loss. Anorexiants are used as therapy for people who are overweight or obese with other risk factors, such as heart disease, high blood pressure, or diabetes. These drugs will not treat other underlying health conditions such as high blood pressure, diabetes, or heart disease. 

Some weight loss drugs mimic natural hormones in the body and do not work in the brain to suppress appetite. All weight loss drugs should be used together with diet and exercise to promote a healthful and longer-lasting weight loss.

To view the latest weight loss drug approvals plus warnings, dosing, drug interactions, and side effects view the Drugs.com Anorexiant Drug Class.

Learn more: The Latest Weight-Loss Treatments 

Saxenda (liraglutide) injection was approved for chronic weight management. It can be used to help you lose weight and keep it off over the long-term.

  • Saxenda is for obese patients, or for overweight patients with at least one weight-related condition such as hypertension, type 2 diabetes, or high cholesterol.
  • This drug is like a hormone (a GLP-1 agonist) that helps to regulate your appetite; it is not a stimulant drug or a controlled substance. It is injected subcutaneously (under the skin) once daily at any time of day, without regard to the timing of meals.
  • In one clinical trial, the average weight loss was 4.5% compared to treatment with a placebo (inactive pill) after one year.
  • Saxenda is not used to manage type 1 or type 2 diabetes.

Contrave (bupropion and naltrexone) was FDA-approved for chronic weight management when added to diet and physical activity. It is also used for obese patients, or for overweight patients with at least one weight-related condition such as hypertension, type 2 diabetes, or high cholesterol.

  • Contrave is an oral extended-release form of two previously approved drugs, naltrexone and bupropion. It is normally given as a total daily dosage of two Contrave tablets given orally twice a day, after initial dose escalation. It is not classified as a controlled substance by the DEA.
  • Bupropion is an antidepressant medicine that also decreases your appetite. Naltrexone is usually given to block the effects of narcotics or alcohol in people with addiction problems, but it may also curb hunger and food cravings.
  • In clinical trials, 36% to 48% of patients lost at least 5 percent of body weight compared to placebo (an inactive treatment).

Qsymia (phentermine and topiramate extended-release): phentermine is an oral capsule appetite suppressant similar to an amphetamine, and topiramate is classified as an anticonvulsant, but has other uses. It is a C-IV controlled substance.

  • Like many other weight loss drugs, Qsymia is used for obese patients, or for overweight patients with at least one weight-related condition such as hypertension, type 2 diabetes, or high cholesterol.
  • Take Qsymia once daily in the morning with or without food. Avoid taking Qsymia in the evening due to the possibility of insomnia.
  • Your doctor will evaluate weight loss after 12 to 24 weeks of treatment with Qsymia. If you have not lost at least 3% to 5% of baseline body weight, Qsymia may not be effective for you. Do not stop treatment unless directed by your doctor as you will need to slowly stop the medicine.

Wegovy (semaglutide) is a once-weekly subcutaneous injection. It is not a controlled substance.

  • Like Saxenda, it is classified as a glucagon-like peptide-1 (GLP-1) receptor agonist. Wegovy was first approved in June 2021.
  • It is used in addition to diet and exercise for long-term weight management in adults who are overweight (BMI ≥27 kg/m2) or obese (BMI ≥30 kg/m2)

In 2020, the FDA requested the withdrawal of lorcaserin (Belviq, Belviq XR) from the U.S. market as the risk of cancer (including pancreatic, lung and colorectal) outweighed any benefit from the drug.

See Also

Sources

  1. Centers for Disease Control and Prevention. Defining Adult Overweight and Obesity. Accessed June 17, 2021 at https://www.cdc.gov/obesity/adult/defining.html
  2. Drugs.com. Obesity. Accessed June 17, 2021 at https://www.drugs.com/health-guide/obesity.html
  3. Centers for Disease Control and Prevention (CDC). Assessing Your Weight. Accessed June 17, 2021 at https://www.cdc.gov/healthyweight/assessing/
  4. Obesity in adults: a clinical practice guideline. CMAJ 2020 August 4;192:E875-91. doi: 10.1503/cmaj.191707 Accessed June 17, 2021.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.