What are the medical causes of weight gain?

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From the Guidelines

Weight gain can be caused by various medical conditions and medications, and it is crucial to identify and address these underlying causes to improve morbidity, mortality, and quality of life. When considering medical causes for weight gain, it is essential to evaluate both conditions and medications that may contribute to this issue. Common medical causes include hypothyroidism, Cushing's syndrome, polycystic ovary syndrome (PCOS), and insulin resistance or diabetes.

Medications Associated with Weight Gain

Certain medications are known to cause weight gain, including:

  • Antipsychotics (like olanzapine and quetiapine) 1
  • Antidepressants (particularly SSRIs like paroxetine and tricyclics like amitriptyline) 1
  • Mood stabilizers (such as lithium and valproate)
  • Corticosteroids (prednisone) 1
  • Some diabetes medications (insulin, sulfonylureas) 1
  • Hormonal contraceptives and beta-blockers (propranolol, metoprolol) 1 These conditions and medications typically cause weight gain by affecting metabolism, increasing appetite, causing fluid retention, or altering how the body stores fat.

Management Strategies

Healthcare providers should carefully review a patient's concomitant medications and, whenever possible, minimize or provide alternatives for medications that promote weight gain 1. When prescribing medications that promote weight gain, clinicians should counsel patients on the risk of weight gain, discuss lifestyle modifications, and monitor weight trajectory 1. Additionally, medications like metformin and topiramate can be considered as adjunctive therapy to counteract the effects of some weight gain-promoting agents 1.

From the FDA Drug Label

ADVERSE REACTIONS ... weight gain ... increased appetite, weight increased The following adverse reactions have been reported with prednisone or other corticosteroids: ... increased appetite and weight gain

Medical causes for weight gain include:

  • Olanzapine (PO): weight gain, increased appetite
  • Prednisone (PO): increased appetite and weight gain, cushingoid state, negative nitrogen balance caused by protein catabolism, fluid retention 2 3

From the Research

Medical Causes of Weight Gain

There are several medical causes of weight gain, including:

  • Hypothyroidism, a condition where the thyroid gland does not produce enough thyroid hormones, which can slow down metabolism and lead to weight gain 4
  • Cushing's syndrome, a condition caused by having too much cortisol in the body, which can lead to weight gain, particularly in the midsection of the body 5, 6
  • Other endocrine disorders, such as polycystic ovary syndrome (PCOS) or growth hormone deficiency, which can also affect weight regulation

Thyroid-Related Weight Gain

Thyroid-related weight gain can occur due to:

  • Hypothyroidism, which can cause a decrease in metabolism, leading to weight gain 4, 7
  • Central hypothyroidism, a condition where the pituitary gland does not produce enough thyroid-stimulating hormone (TSH), which can also lead to weight gain 5, 6
  • Thyroid hormone replacement therapy, which can sometimes cause weight gain if the dosage is too high or if the patient has other underlying medical conditions 7

Other Medical Conditions

Other medical conditions that can cause weight gain include:

  • Cushing's syndrome, which can cause weight gain due to excess cortisol in the body 5, 6
  • Certain medications, such as steroids or certain antidepressants, which can increase appetite or slow down metabolism, leading to weight gain
  • Sleep apnea or other sleep disorders, which can disrupt hormones that regulate hunger and fullness, leading to weight gain

Note: There is no direct evidence in the provided studies to support the claim that the other medical conditions listed above are causes of weight gain. However, it is well-established in the medical literature that these conditions can contribute to weight gain.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

The Hypothalamic-Pituitary-Thyroid Axis in Cushing Syndrome Before and After Curative Surgery.

The Journal of clinical endocrinology and metabolism, 2021

Research

Cushing's Syndrome Effects on the Thyroid.

International journal of molecular sciences, 2021

Research

Optimal Thyroid Hormone Replacement.

Endocrine reviews, 2022

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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