OVERVIEW

What is drug-induced obesity?

Obesity refers to excessive fat accumulation and/or abnormal distribution in the body, leading to weight gain. Obesity caused by medication use is called drug-induced obesity, which falls under secondary obesity.

Who is prone to drug-induced obesity?

This condition can occur at any age. Generally, anyone using medications that may cause weight gain is at risk.

SYMPTOMS

How is drug-induced obesity diagnosed?

During or after the use of relevant medications, weight increases to meet the diagnostic criteria for obesity. Meeting one of the following two conditions can diagnose obesity:

• Body mass index (BMI) ≥ 28.0 kg/m², where BMI = weight (kg) / height² (m);

• Waist circumference ≥ 90 cm for men or ≥ 85 cm for women.

Can drug-induced obesity lead to serious consequences?

The occurrence of many severe chronic diseases is associated with this condition, including:

• Cardiovascular diseases: such as heart disease and stroke, currently the leading cause of death worldwide;
  
  
• Diabetes: has become a global epidemic. Diabetes can also increase the risk of death;
  
  
• Musculoskeletal disorders: particularly osteoarthritis;
  
  
• Certain cancers: such as endometrial cancer, breast cancer, and colon cancer.

CAUSES

Which common medications can lead to drug-induced obesity?

Many medications can cause weight gain and contribute to this condition, including:

• Antipsychotics: Clozapine, Olanzapine, etc.;

• Antidepressants: Amitriptyline, Clomipramine, etc.;

• Antiepileptic drugs: Carbamazepine, etc.;

• Hypoglycemic agents: Pioglitazone, etc.;

• Antihistamines: Cyproheptadine, etc.;

• Corticosteroids: Prednisone, etc.;

• Progestin-based contraceptives may also contribute to weight gain.

Compared to adults, Olanzapine may induce particularly severe weight gain and hyperlipidemia in adolescents.

DIAGNOSIS

What tests are needed for the diagnosis of drug-induced obesity?

Height, weight, waist circumference, blood glucose, blood pressure, blood lipids, etc., should be measured.

Why are these tests performed for the diagnosis of drug-induced obesity? What is their purpose?

• Height and weight: Used to calculate whether the body mass index meets the criteria for obesity.

• Waist circumference: Used to assess whether it meets the diagnostic criteria for abdominal obesity.

• Blood pressure: Used to evaluate whether hypertension is present.

• Blood glucose and lipids: Used to assess whether diabetes and hyperlipidemia are present.

Which diseases is drug-induced obesity easily confused with?

This condition is easily confused with simple obesity, hypothalamic obesity, hypothyroidism, growth hormone deficiency, and other diseases that cause obesity. Differentiation can be made based on medical history and relevant tests.

TREATMENT

Which department should I visit for drug-induced obesity?

Endocrinology.

How should drug-induced obesity be treated?

• First, lifestyle modifications:

  • Develop a personalized diet plan based on height and weight, limit total calorie intake, avoid sugary foods or drinks, and refrain from eating before bedtime or overeating.

  • Increase physical activity, engaging in at least 30 minutes of moderate-intensity exercise (requiring some effort, with increased heart rate and breathing but not to the point of breathlessness) daily, at least 5 days a week.

  • If necessary, discontinue or switch medications that contribute to obesity.

• Second, medication-assisted weight loss may be considered under the following conditions:

  • Strong appetite, difficulty resisting hunger before meals, and large meal portions.

  • Comorbidities such as hyperglycemia, hypertension, dyslipidemia, or fatty liver.

  • Joint pain under weight-bearing conditions.

  • Obesity-related breathing difficulties or obstructive sleep apnea syndrome.

  • Failure to achieve a 5% weight reduction or continued weight gain after 3–6 months of dietary control and increased physical activity, regardless of the presence of the above complications.

  • Available medications in China include phentermine hydrochloride, amfepramone hydrochloride, and orlistat. Certain antidiabetic drugs like metformin and liraglutide may also be used for weight loss in patients with comorbid diabetes.

• Third, surgical treatment may be considered for severe obesity. Additionally, maintaining a positive mood is crucial for managing this condition.

What precautions should be taken when using medication for drug-induced obesity?

During medication use, the following should be noted:

• All weight-loss medications must be used under medical supervision, and patients should be fully informed about potential side effects and risks before use. Regular follow-ups are required to monitor possible risks.

• Do not expect medications to permanently resolve obesity—they are only supplementary to strict dietary management and consistent exercise.

• Weight-loss drugs are contraindicated during pregnancy. Women of childbearing age must use reliable contraception while taking these medications.

Common adverse effects of medications include:

• Phentermine hydrochloride and amfepramone hydrochloride: May cause dry mouth, insomnia, dizziness, mild blood pressure elevation, and/or increased heart rate. Blood pressure and heart rate should be monitored during treatment.

• Orlistat:

  • May lead to oily discharge, flatulence, fecal urgency, or incontinence, but these effects tend to diminish over time.

  • Orlistat interferes with the absorption of fat-soluble vitamins (A, D, E, and K), so supplementation is recommended (taken at least 2 hours before or after orlistat).

  • Orlistat may also cause liver damage. Patients should monitor for symptoms like nausea, vomiting, loss of appetite, pale stools, or yellowing of the skin and urine, and seek medical attention immediately if these occur.

Is follow-up necessary after treatment for drug-induced obesity? How should it be done?

Yes, follow-up is required.

• If no weight-loss medications are used, monitor weight, waist circumference, and blood pressure monthly.

• If weight-loss medications are used, monitor weight, blood pressure, heart rate, and adverse effects weekly for the first 4 weeks, then monthly thereafter.

• For antidiabetic drugs like metformin and liraglutide, blood glucose levels should also be monitored.

DIET & LIFESTYLE

What should patients with drug-induced obesity pay attention to in their diet?

As mentioned earlier, patients with this condition need to strengthen dietary control, determine total calorie intake under medical guidance based on height and weight, avoid sugary foods or beverages, refrain from eating before bedtime and overeating, and consume more vegetables.

Is drug-induced obesity hereditary?

This condition is caused by medication and is not hereditary.

PREVENTION

Can drug-induced obesity be prevented?

It cannot be completely prevented, but the risk of weight gain can be minimized.

• First, avoid the misuse of medications that may cause weight gain;

• Second, if weight-gain-inducing drugs must be used, pay attention to diet control, moderate exercise, and monitor weight and waist circumference during treatment. Seek medical advice early if an upward trend is observed.