Do Any Weight Loss Pills Really Work?

There are a number of different types of medications used for weight loss.

Weight loss pills are medications used to treat people who are overweight or obese. These kinds of medications are used along with healthy eating, physical activity, and behavior modification. 

Patients who are candidates for weight loss drug therapy include those individuals with a body mass index (BMI) 30 kg/m2 or greater, or a BMI of 27 to 29.9 kg/m2 with weight-related comorbidities, who have been unable to achieve doctor-prescribed weight-loss goals with lifestyle modifications. 

There are a number of different types of medications used for weight loss. 

Drugs that alter fat digestion include:

• Orlistat (Alli [available over-the-counter OTC], Xenical) alters fat digestion by inhibiting pancreatic lipases, and fat is eliminated in feces. It can inhibit the absorption of approximately 25 to 30 percent of calories ingested as fat. In addition to weight loss, orlistat may help with blood sugar regulation, lowering fats, and maintaining blood pressure. It is considered relatively safe; however, gastrointestinal side effects are often intolerable for patients. 
  • Side effects of orlistat include:
    • Gastrointestinal cramps
    • Gas (flatulence)
    • Fecal incontinence
    • Oily spotting 
    • Gas with discharge 
    • Lowered absorption of fat-soluble vitamins (A, D, E, K) and beta-carotene 
    • A multivitamin is often recommended when taking orlistat for this reason
    • Acute kidney injury 
    • Severe liver injury (rare)

GLP-1 receptor agonists used for weight loss include:

• Liraglutide (Saxenda, Victoza) has positive effects on blood sugar, in addition to helping with weight loss. It is the preferred medication for use in patients with type 2 diabetes, especially those with heart problems, though it may also be used in patients who are not diabetic. It is not fully understood how GLP-1 receptor agonists cause weight loss. Its positive effects on blood sugar may play a role. These drugs seem to suppress appetite. They also slow the movement of food through the stomach which may cause people to feel full more quickly when eating, thus resulting in eating less. GLP-1 receptor agonists are usually used in combination with metformin or another oral diabetes medication for patients with type 2 diabetes, especially when weight loss is an important consideration. Weight loss is common with GLP-1 receptor agonists.
  • Side effects of liraglutide include:
    • Nausea
    • Vomiting
    • Diarrhea
    • Low blood sugar
    • Loss of appetite
    • Pancreatitis
    • Gallbladder disease
    • Kidney impairment

Combination drugs used for weight loss include:

• Phentermine-topiramate (extended-release) (Qsymia) is used in men and postmenopausal women with obesity who do not have high blood pressure (hypertension) or coronary heart disease. The combination of phentermine and topiramate has been shown to boost weight loss in the first year of use. Topiramate increases the risk of birth defects and should be used with caution in women of childbearing potential.
  • Side effects of phentermine-topiramate include:
    • Dry mouth 
    • Constipation 
    • Numbness and tingling
    • Depression
    • Anxiety
    • Disturbance in attention
    • Increased heart rate 
• Naltrexone-bupropion (sustained-release) (Contrave) produces similar weight loss as orlistat, but it has more side effects. It is generally not recommended for first-line drug therapy and maybe prescribed for obese people who smoke and who are seeking drug therapy for smoking cessation and obesity. 
  • Side effects of naltrexone-bupropion include:
    • Nausea 
    • Headache 
    • Constipation 
    • Insomnia
    • Vomiting
    • Dizziness
    • Dry mouth

Sympathomimetic drugs used for weight loss include:

• Phentermine (Adipex-P, Lomaira), benzphetamine, phendimetrazine, and diethylpropion are only approved for short-term (12 weeks) use because they have more side effects and have the potential for abuse. For this reason, these drugs are not recommended for use in patients with coronary heart disease, uncontrolled high blood pressure (hypertension), hyperthyroidism, or in patients with a history of drug abuse.
  • Side effects of sympathomimetic drugs include:
    • Increased heart rate
    • Increased blood pressure 
    • Insomnia
    • Dry mouth
    • Constipation
    • Nervousness

All weight-loss medications are designed for use along with healthy eating, physical activity, and healthy lifestyle changes. All the drugs discussed above have been proven to reduce weight when taken as directed and combined with diet, exercise, and behavior modifications. 

The choice of medication depends on the patient’s overall health, the presence of any other underlying conditions, patient preferences, adverse side effects of each particular drug, and insurance coverage and cost.

Over-the-counter dietary supplements marketed for weight loss are generally not recommended due to low-quality evidence or lack of evidence of their effectiveness, and the concern for potential adverse side effects. Talk to your doctor before taking any over-the-counter (OTC) supplement for weight loss.

Bariatric surgery (weight loss surgery) may be an alternative option for those who do not have success with medications and who meet certain surgical criteria.