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4 Clinical Insights About Mirtazapine and Weight Gain

Last Updated: March 2, 2024

Reviewed by Dr. Ash Bhatt

Living with depression causes significant challenges, impacting mental and physical well-being.

Mirtazapine stands as a valuable solution in managing this debilitating disorder, offering relief for many individuals. Yet, the efficacy of mirtazapine is accompanied by a notable side effect: weight gain.

While the medication proves instrumental in alleviating the burdens of depression, its impact on appetite, metabolism, and subsequent weight changes requires thoughtful consideration. This article will provide insights into the relationship between mirtazapine and weight gain while offering evidence-based strategies for managing this particular aspect of treatment.

What is Mirtazapine?

Trade name: Remeron®

Generic name: Mirtazapine

Mirtazapine, also known by its trade name Remeron, is a medication primarily prescribed for treating major depressive disorder. It belongs to the class of antidepressants known as tetracyclic antidepressants (TeCAs). Mirtazapine works by adjusting neurotransmitter levels in the brain, targeting specific receptors to enhance serotonin and norepinephrine release, improving mood and relieving depressive symptoms.

This drug is also prescribed for off-label clinical uses for individuals experiencing insomnia or anxiety symptoms alongside depression. Mirtazapine is typically administered orally, and its dosage is individualized based on the patient’s response and tolerability.

4 Clinical Reasons to Understand the Relation between Mirtazapine and Weight Gain

  • Appetite Stimulation

Evidence shows Mirtazapine plays a significant role in appetite stimulation, resulting in an elevated consumption of calories.

This medication actively impacts histamine receptors within the central nervous system (CNS). By acting on these receptors, Mirtazapine triggers an increase in the sensation of hunger. The heightened hunger response can manifest as a persistent craving for food, especially sweets.

This heightened appetite is one of the primary factors contributing to weight gain in certain individuals undergoing Mirtazapine treatment. Notably, histamine receptor activation is linked to the stimulation of the orexigenic pathway, which regulates the sensation of hunger.

  • Metabolic Effects of Mirtazapine and Weight Gain

Mirtazapine has a relevant influence on metabolic processes, exerting a notable impact on how the body manages energy storage. This influence is a potential contributor to weight gain in individuals undergoing treatment.

This metabolic shift is notably characterized by a preference for carbohydrate substrates in energy metabolism, driven by the medication’s targeted actions on neurotransmitter systems and hormonal regulation. Remeron causes this shift following the next biological events:

Neurotransmitter modulation

Mirtazapine influences vital neurotransmitter systems, such as serotonin receptors (5-HT2 and 5-HT3), alpha-2 adrenergic receptors, and histamine receptors within the central nervous system.

Alpha-2 adrenergic receptor antagonism

Mirtazapine specifically targets alpha-2 adrenergic receptors. As an antagonist, it interferes with their normal functioning. A shift in this functioning is the starting point of the correlation between Mirtazapine and weight gain.

Impact on norepinephrine release

Alpha-2 adrenergic receptors typically regulate the release of norepinephrine, a neurotransmitter crucial for maintaining metabolic rate and energy expenditure.

Hindrance of norepinephrine release

Mirtazapine’s antagonism of alpha-2 adrenergic receptors impedes the release of norepinephrine. This interference disrupts the usual balance of neurotransmitters involved in metabolic regulation.

Metabolic slowdown

With reduced norepinephrine release, there is a subsequent metabolic slowdown. Norepinephrine is instrumental in supporting the body’s natural calorie-burning processes.

Impact on caloric expenditure

The metabolic slowdown reduces the body’s natural ability to burn calories efficiently. This altered metabolic state creates an environment conducive to weight gain.

Mirtazapine’s metabolic effects drive a shift towards carbohydrate substrate preference in energy metabolism. This shift manifests as an increased reliance on carbohydrates for energy, promoting their storage as fat in the body, which explains Mirtazapine and weight gain as a side effect.

  • Fat Distribution Changes

Mirtazapine has been linked to the development of insulin resistance, a condition where cells become less responsive to the effects of insulin.

Insulin, a hormone crucial for regulating blood sugar and lipid metabolism, usually aids in storing fat. However, in the presence of insulin resistance, this process becomes inefficient, contributing to altered fat distribution.

Mirtazapine-induced insulin resistance may promote obesity, characterized by increased fat accumulation in the abdominal area. Changes in fat deposition from subcutaneous (under the skin) to visceral (around organs) could also be considered. Also, Mirtazapine use has an impact on the function of adipocytes, the cells responsible for storing fat.

  • Leptin Signaling, Mirtazapine and Weight Gain

Mirtazapine may interfere with the functioning of leptin receptors in the hypothalamus, the brain region responsible for regulating appetite and satiety. This interference can lead to diminished sensitivity to leptin, reducing the effectiveness of the hormone in signaling fullness.

Mirtazapine-induced changes in leptin signaling may contribute to the development of leptin resistance.

Leptin resistance occurs when the brain becomes less responsive to the hormone’s signals, rendering it less effective in controlling appetite and weight. Mirtazapine-induced leptin resistance may render high leptin levels ineffective in controlling weight gain. Despite elevated leptin levels, the brain’s reduced sensitivity to signals fails to curb excessive food intake and prevent Mirtazapine and weight gain.

How Much Weight Can You Gain During Mirtazapine Treatment?

Remeron can rapidly and cumulatively induce weight gain, influenced by various factors, including individual characteristics.

The extent of body mass increase can range from a few pounds to approximately 30 lbs. A study featured in the Journal of Clinical Psychiatry revealed that participants gained an average of 8 lbs over a 6-week period. Fortunately, discontinuing Remeron typically facilitates the relatively easy loss of the acquired fat mass.

How to Avoid and Manage Weight Gain while Taking Mirtazapine?

To proactively address Remeron-induced weight gain, consult with your doctor. Before starting Mirtazapine treatment, assess potential risks through comprehensive testing and disclose existing health conditions and medications.

  • To avoid Mirtazapine and weight gain, don’t self-treat. Instead, focus on a healthy diet, consulting with a dietician or nutritionist for effective weight management strategies.
  • Incorporate regular exercise to not only counteract drug-induced weight gain but also promote physical and mental health.
  • Monitor weight gain consistently, evaluating the impact of specific doses and durations to make informed adjustments.
  • Remeron and moderate alcohol intake aren’t associated with weight gain; excessive alcohol consumption, particularly with antidepressants like Remeron, may amplify weight-related risks and trigger additional side effects.

Don’t Waste Time, Seek Professional Help

Regular consultations and a responsible approach with a doctor can prevent Mirtazapine and weight gain.

For those facing weight issues from Remeron misuse, seeking prompt, professional help, including substance abuse treatment and therapies, is crucial for recovery.

People Also Ask

What is the average weight gain on Mirtazapine?

The average weight gain on Mirtazapine is around 3.3 to 9.9 lbs (1.5 to 4.5 kg). Individual responses vary, and dosage, duration, and lifestyle influence outcomes.

How do you avoid weight gain on Mirtazapine?

To mitigate weight gain on Mirtazapine, prioritize a balanced diet, exercise regularly and consult your doctor for personalized strategies. Monitoring weight and discussing concerns promptly enhance proactive management.

Is it harder to lose weight on Mirtazapine?

Yes, weight loss can be challenging during treatment. Mirzatapine and weight gain correlate due to increased appetite and metabolic effects. Adopting a healthy lifestyle, including diet, exercise, and consulting with a healthcare professional can help manage weight effectively.

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Page Sources

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Published on: November 25th, 2019

Updated on: March 2nd, 2024

María José Petit-Rodríguez

About Author

María José Petit-Rodríguez

Medically Reviewed by

Dr. Ash Bhatt

Throughout his professional life, Dr. Bhatt has been conferred with diplomate status by the American Board of Psychiatry and Neurology, certifying him in both adult and child/adolescent psychiatry. His experiences in emergency rooms, frequently encountering patients with simultaneous health and addiction issues, directed his attention to these specific fields.

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