Depression
Videos
Overview
Depression is a common and serious medical condition that affects mood, thinking, sleep, appetite and energy. Depression and obesity are closely linked in both directions: a large meta-analysis found that people with obesity had about a 55% higher risk of developing depression, and people with depression had about a 58% higher risk of developing obesity (Luppino et al., Archives of General Psychiatry, 2010). Shared biology, including inflammation and stress hormones, along with weight stigma, reduced activity and emotional eating, help explain this two-way relationship.
Depression is also common among people seeking bariatric surgery; a large review estimated that about one in five bariatric candidates has current depression (Dawes et al., JAMA, 2016). Treating depression improves quality of life and supports success with weight-loss treatment. Many patients experience improvement in depressive symptoms after bariatric surgery, but ongoing mental health support remains important, because some patients face new emotional challenges after surgery (Dawes et al., JAMA, 2016) (Castaneda et al., Obesity Surgery, 2019).
Causes
- Biological factors: genetics, brain chemistry and hormonal changes
- Chronic inflammation, which is elevated in obesity
- Chronic stress and life events
- Weight stigma and discrimination
- Chronic illness and pain, including obesity-related conditions
- Poor sleep and sleep apnea
- Medications and substance use
Risk Factors
- Personal or family history of depression
- Obesity, especially severe obesity (Luppino et al., Archives of General Psychiatry, 2010)
- Trauma and chronic stress
- Chronic medical conditions
- Social isolation
- Alcohol or substance use
Who It Affects
Depression affects people of all ages and backgrounds and is more common in women. It is particularly common among people with severe obesity and among patients considering weight-loss surgery.
Complications
- Emotional eating and weight gain; see emotional eating
- Reduced physical activity
- Difficulty following treatment plans
- Substance use, including alcohol
- Worsening of chronic diseases
- Self-harm and suicide in severe cases
Symptoms
- Persistent sadness or emptiness
- Loss of interest or pleasure in activities
- Changes in appetite and weight
- Sleeping too much or too little
- Fatigue and low energy
- Feelings of worthlessness or guilt
- Difficulty concentrating
- Thoughts of death or suicide
Diagnosis
- Screening questionnaires such as the PHQ-9
- Clinical evaluation by a physician or mental health professional
- Exclusion of medical causes such as thyroid disease, vitamin deficiencies and medication effects
- Psychological evaluation before bariatric surgery, which is standard practice and helps identify patients who would benefit from added support (Sogg et al., ASMBS Recommendations for the Presurgical Psychosocial Evaluation, Surgery for Obesity and Related Diseases, 2016)
Differential Diagnosis
- Hypothyroidism
- Vitamin B12 or vitamin D deficiency
- Sleep apnea
- Bipolar disorder
- Grief and adjustment disorders
- Medication side effects
Lifestyle Modifications
- Stay physically active; exercise has antidepressant effects.
- Keep a regular sleep schedule.
- Maintain social connections and join support groups.
- Limit alcohol, especially after bariatric surgery.
- Eat regular, balanced meals.
Treatment Options
- Psychotherapy, including cognitive behavioral therapy
- Antidepressant medications, chosen with attention to weight effects; some medications may need dose adjustment after bariatric surgery because absorption changes
- Treatment of contributing conditions such as sleep apnea
- Weight-loss treatment, which can improve mood and self-esteem for many patients; see medical weight loss and bariatric surgery
- Ongoing mental health follow-up after surgery; see the mental health, body image and alcohol guide
When to See a Doctor
See a doctor or mental health professional if you have felt down, hopeless or lost interest in things for more than two weeks, or if mood problems are affecting your eating, work or relationships.
When to Seek Treatment
If you have thoughts of harming yourself, call or text 988 (the Suicide and Crisis Lifeline) or go to the nearest emergency department right away.
Long-Term Outlook
Ongoing attention to mental health, including after bariatric surgery, helps patients sustain both emotional well-being and long-term weight loss (Castaneda et al., Obesity Surgery, 2019).
Related Reading and Videos
Read more in our articles Mental Preparation for Bariatric Surgery: A Complete Patient Guide and GLP-1 Medications and Your Brain: Addiction, Dementia, and Neuroprotection. Watch 10% of Deaths After Bariatric Surgery: The Mental Side Nobody Warns You About and The 7 Psychology Tricks That Finally Break Emotional Eating — Even When Nothing Else Has Worked on our video library. Related conditions include Anxiety.
Prognosis
Depression is highly treatable. Most people improve with therapy, medication or both, and treating depression supports better outcomes with weight-loss treatment.
Why Choose Dr. de la Cruz-Muñoz
Dr. de la Cruz-Muñoz's program recognizes that mental health and weight are deeply connected. Patients receive psychological evaluation before surgery, access to support groups and behavioral health resources, and follow-up that continues long after the operation.
Dr. de la Cruz-Muñoz has co-authored research on depression, stress biomarkers and weight loss in young, ethnically diverse bariatric surgery patients (Messiah et al., Bariatric Surgical Practice and Patient Care, 2020).
Dr. de la Cruz-Muñoz has been performing bariatric surgery for over 25 years and has completed more than 9,000 bariatric operations — a volume few surgeons reach.
Featured Procedures
FAQ
Long-term risks include reoperation (about 5–22%, higher after gastric bypass), procedure-specific issues such as marginal ulcers or internal hernia after bypass and reflux after sleeve, nutritional deficiencies requiring lifelong supplements, and mental-health considerations (Arterburn et al., JAMA, 2020; Courcoulas et al., BMJ, 2023). These are real but manageable with lifelong vitamin monitoring and structured multidisciplinary follow-up.
Bariatric surgery does not automatically cause depression or anxiety, but these conditions can persist, worsen, or develop after surgery. Pre-existing depression, anxiety, trauma, eating disorders, relationship stress, and major body changes may increase risk. Therapy, medication management, support groups, and regular follow-up can help.
Yes. Depression and anxiety often improve within the first year, but some patients experience mood dips between years 1–3, especially if weight expectations aren’t met or excess skin becomes distressing. Alcohol‑use disorder risk also increases, particularly after gastric bypass, so monitoring is essential.
Some fatigue in the first few weeks is expected while calorie intake is very low. But exhaustion that lasts for months, or that appears later and worsens, is not something to simply wait out. It usually points to a measurable cause such as a nutrient deficiency, low protein and muscle, blood-sugar crashes, residual sleep apnea, or depression, all of which can be identified and treated (Mechanick et al., Obesity, 2020).
