Medical Condition-Related Weight Gain

From hormonal imbalances to certain medications, medical reasons for weight gain are more common than you may realise. Understanding these causes is the first step toward developing an effective treatment plan. Read on for more on medical condition-related to weight gain.

 

Medically reviewed by Danny Chu, HCPC-Registered Physician Associate (PA38670).

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What Medical Conditions Can Cause Weight Gain?

A range of underlying health conditions can lead to weight gain. The most frequent include hormonal conditions such as:

  • Polycystic ovary syndrome (PCOS)/Polyendocrine metabolic ovarian syndrome (PMOS)
  • Cushing's syndrome 
  • Menopause
  • Mental health conditions like depression or anxiety
  • Metabolic disorders such as hypothyroidism and diabetes
  • Certain medications  

Hormonal Conditions Associated With Weight Gain

Polycystic Ovary Syndrome (PCOS)

Update May 2026: Polycystic ovary syndrome (PCOS) has been officially renamed polyendocrine metabolic ovarian syndrome (PMOS) to better reflect its nature as a lifelong hormonal and metabolic disorder. The transition to PMOS will be fully implemented by 2028. 

 

PCOS, increasingly referred to as PMOS, is a common condition affecting women of reproductive age. It causes irregular periods, missed menstrual cycles and elevated androgen levels, which can lead to acne and oily skin. 

 

Insulin resistance makes it harder for the body to regulate blood sugar and increases the tendency to store body fat, particularly around the abdomen. This combination of hormonal and metabolic factors can make it significantly harder to lose weight. 

 

Insulin resistance in PCOS is also closely linked to metabolic syndrome. This cluster of conditions includes high blood pressure, elevated blood sugar and excess abdominal fat, together increasing the risk of heart disease and type 2 diabetes. 

Read more on hormonal imbalance & weight gain

Cushing's Syndrome 

Cushing’s syndrome, also called Endogenous pathologic hypercortisolism, results from prolonged excess cortisol production. It often occurs due to a tumour on the pituitary or adrenal gland.

 

Excessive cortisol production is associated with abdominal fat accumulation, leading to a distinctive pattern of weight gain around the midsection, a rounded face and purple stretch marks. Treatment options include surgery, radiation, or medication to lower cortisol levels. 

Menopause

Menopause typically occurs between the ages of 45 and 55 and brings significant hormonal changes. Lower oestrogen levels alter how the body distributes fat, increasing abdominal fat even without an increase in overall body weight. 


Age-related changes in metabolism and body composition may make weight management more challenging during this life stage. Hot flushes can disrupt sleep, which further affects appetite regulation and weight management. Poor sleep is also a risk factor for sleep apnea, a condition more common in people with excess weight. 

Weight gain during menopause may affect more than just physical health. Studies suggest that increases in body weight and body mass index (BMI) can be associated with anxiety, depression and reduced quality of life.  

Menopause weight gain: Causes & solutions

Medications & Medical Weight Gain

Several medications are associated with weight gain as a side effect. The most commonly implicated include:

Antidepressants and antipsychotics:

These can increase appetite and alter metabolism, with weight gain depending on the medication and the individual.

Corticosteroids:

Used to treat inflammation, corticosteroids increase appetite and promote fat storage, particularly with long-term use.

Diabetes medications:

Some insulin-based treatments can cause weight gain by promoting the storage of energy as fat.

The ways medications can cause sudden weight gain vary. Some medications increase appetite directly; others cause fluid retention, and certain drugs slow metabolism.

 

It is important never to stop a prescribed medication due to weight concerns without first discussing suitable alternatives with a healthcare professional. A medical professional can help weigh up the potential risks and benefits and adjust the treatment plan accordingly to return to a healthy weight.   

Depression & Other Mental Health Conditions

The Stress Hunger Loop How Stress Can Influence Appetite Weight and Energy

Depression and other mental health conditions can contribute to weight gain through several overlapping pathways. Behavioural factors can include:

  • Emotional eating
  • Reduced physical activity and exercise 
  • Unhealthy food choices  

At a physiological level, depression has been associated with changes in cortisol regulation, which may contribute to abdominal fat accumulation and disrupt appetite regulation.

Insomnia that is frequently associated with depression further disrupts hunger hormones, increasing the likelihood of overeating. Certain antidepressants can also contribute to weight gain as a side effect, compounding these challenges.

Unmanaged weight gain in people with depression can significantly impair long-term physical functioning, making integrated management of both conditions important.

Explore the link between cortisol & sudden weight gain

Fluid Retention & Sudden Weight Gain

Fluid retention (oedema) occurs when excess fluid builds up in the body’s tissues, causing swelling in the hands, feet, and ankles, and can lead to sudden weight gain in a short period. It is often a sign of an underlying systemic disease that prevents the body from processing fluid normally.

Main medical causes include:

Heart disease:

Heart failure reduces the heart's ability to pump blood efficiently, leading to fluid accumulation in the body.

Liver disease:

Liver conditions such as cirrhosis can cause fluid to pool in the abdomen (ascites) and limbs.

Kidney disease:

Impaired kidneys cannot adequately filter and excrete fluid.

A high-salt diet can also worsen fluid retention. If sudden weight gain occurs alongside swelling, shortness of breath, or high blood pressure, get medical attention without delay.

Metabolic Disorders

Hypothyroidism

The thyroid gland regulates metabolism with hormones that control how the body uses energy. With an underactive thyroid (hypothyroidism), hormone levels fall and slow the metabolism, which can lead to weight gain.

 

Other symptoms include fatigue, constipation, and cold intolerance.  

 

Hypothyroidism is more common in women than in men and is confirmed through a blood test. With the right treatment, you can often stabilise your metabolic function and weight.

Diabetes

Both type 1 and type 2 diabetes are associated with changes in body weight. According to government data, nearly 90% of adults in the UK with type 2 diabetes are overweight, and the condition is linked to increased appetite and reduced physical activity. 

 

Insulin, used to manage blood sugar in both types of diabetes, promotes energy storage in fat cells and can lead to weight gain. Lifestyle factors, alongside healthy eating and medical management, are very important in managing diabetes.  Research suggests that losing 5–7% of body weight may reduce the risk of developing type 2 diabetes in those with risk factors.    

When You Should Get Medical Advice About Weight Gain

A Womans Feet On A Scale

You should speak to a doctor if you experience:

  • Sudden weight gain with no obvious lifestyle reasons
  • Unexplained changes in body weight over a short period
  • Weight gain that begins after starting a new medication
  • Other symptoms such as swelling, fatigue, changes in mood, irregular periods or cold intolerance

Early investigation allows for an accurate diagnosis and a suitable treatment plan to be developed before complications arise.

Find more reliable, evidence-based content on medical condition-related weight gain and other health concerns, reviewed by our HPCP-registered medical professionals. 

Disclaimer: The information on this page is intended for general educational purposes only. This should not be considered a substitute for personalised medical advice.

At Envigore, we approach conversations around weight loss with empathy, clinical understanding and a commitment to evidence-based information. 

We encourage readers to review the medical journals and resources cited throughout this medical causes for weight gain page to support informed understanding.

  1. PCOS officially renamed to Polyendocrine Metabolic Ovarian Syndrome (PMOS) | Endometriosis UK. (n.d.). https://www.endometriosis-uk.org/pcos-officially-renamed-polyendocrine-metabolic-ovarian-syndrome-pmos

  2. Teede HJ, Misso ML, Costello MF, Dokras A, Laven J, Moran L, Piltonen T, Norman RJ; International PCOS Network. Recommendations from the international evidence-based guideline for the assessment and management of polycystic ovary syndrome. Fertil Steril. 2018 Aug;110(3):364-379. doi: 10.1016/j.fertnstert.2018.05.004. Epub 2018 Jul 19. PMID: 30033227; PMCID: PMC6939856. 

  3. Lynnette K Nieman, Cushing’s syndrome: update on signs, symptoms and biochemical screening, European Journal of Endocrinology, Volume 173, Issue 4, Oct 2015, Pages M33–M38, https://doi.org/10.1530/EJE-15-0464

  4. Davis, S. R., Castelo-Branco, C., Chedraui, P., Lumsden, M. A., Nappi, R. E., … Shah, D. (2012). Understanding weight gain at menopause. Climacteric, 15(5), 419–429. https://doi.org/10.3109/13697137.2012.707385

  5. Domecq JP, Prutsky G, Leppin A, Sonbol MB, Altayar O, Undavalli C, Wang Z, Elraiyah T, Brito JP, Mauck KF, Lababidi MH, Prokop LJ, Asi N, Wei J, Fidahussein S, Montori VM, Murad MH. Clinical review: Drugs commonly associated with weight change: a systematic review and meta-analysis. J Clin Endocrinol Metab. 2015 Feb;100(2):363-70. doi: 10.1210/jc.2014-3421. Epub 2015 Jan 15. PMID: 25590213; PMCID: PMC5393509. 

  6. Luppino FS, de Wit LM, Bouvy PF, et al. Overweight, Obesity, and Depression: A Systematic Review and Meta-analysis of Longitudinal Studies. Arch Gen Psychiatry. 2010;67(3):220–229. doi:10.1001/archgenpsychiatry.2010.2 

  7. Cho S, Atwood JE. Peripheral edema. Am J Med. 2002 Nov;113(7):580-6. doi: 10.1016/s0002-9343(02)01322-0. PMID: 12459405. 

  8. Pearce, EN. Thyroid hormone and obesity. Current Opinion in Endocrinology & Diabetes and Obesity 19(5):p 408-413, October 2012. | DOI: 10.1097/MED.0b013e328355cd6c 

  9. Knowler WC, Barrett-Connor E, Fowler SE, Hamman RF, Lachin JM, Walker EA, Nathan DM; Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. 2002 Feb 7;346(6):393-403. doi: 10.1056/NEJMoa012512. PMID: 11832527; PMCID: PMC1370926. 

  10. Gatineau, M., Hancock, C., Holman, N., Outhwaite, H., Oldridge, L., Christie, A., & Ells, L. (2014). Adult obesity and type 2 diabetes. Public Health England. https://assets.publishing.service.gov.uk/media/5a7f069140f0b6230268d059/Adult_obesity_and_type_2_diabetes_.pdf

About Your Clinical Team

This content was medically reviewed and approved by Danny Gian Hou Chu, a HCPC-Registered Physician Associate (PA38670), who oversees all prescribing decisions at Envigore.

All prescriptions are dispensed by Right Medicine Pharmacy, a GPhC-Registered Pharmacy (No. 9012382).

Nutritional guidance and lifestyle support are provided by Veronica Giudice, a HCPC-Registered Dietitian (DT26570) and British Dietetic Association member.

Last medically reviewed: June 2026