Morbid Obesity

What is morbid obesity?

Morbid obesity (medically: class III obesity) is a Body Mass Index of 40 or higher. In concrete terms, for someone of 1.70 metres this means a weight of 116 kilograms or more; for 1.80 metres it is 130 kilograms or more.

The term 'morbid' (disease-related) refers to the demonstrably increased risk of serious conditions. It is a medical diagnosis, not a judgement of the person. Some sources also use 'severe obesity' or 'clinically severe obesity'.

An extension: at a BMI between 35 and 40 with a serious accompanying disease (such as poorly controlled type 2 diabetes, hypertension, sleep apnoea, or weight-dependent osteoarthritis), a person is clinically treated as if morbid obesity were present.

How is it diagnosed?

The diagnosis is based on BMI plus additional measurements. BMI alone is a crude measure; waist circumference, body composition and metabolic health are also taken into account in the assessment.

• BMI calculation: weight (kg) divided by height (m) squared. BMI ≥40 = morbid obesity.
• Measuring waist circumference: at ≥102 cm for men, ≥88 cm for women there is central fat with increased metabolic risk.
• Blood tests: glucose, HbA1c, lipid panel, liver and kidney function, thyroid, vitamin D.
• Blood pressure measurement (often with a large cuff — small cuffs give falsely high readings in obesity).
• Sleep apnoea screening (Epworth questionnaire, or a sleep study if suspected).
• Comorbidity assessment: cardiovascular, mental health, joints, fertility.

Health risks

The health impact of morbid obesity is substantial but largely reversible with serious weight reduction.

• Type 2 diabetes: 5-7 times higher risk; already present in many.
• Cardiovascular: heart attack, stroke, heart failure — 2-4 times higher risk.
• Sleep apnoea: present in more than 50% of people with morbid obesity; shortens life if untreated.
• Cancer: 30-40% higher risk of colon, endometrial, breast, kidney, oesophageal and pancreatic cancer.
• Fatty liver disease (MASLD/MASH): can lead to liver cirrhosis within 10-15 years.
• Osteoarthritis: especially knees and hips; weight loss sometimes gives full recovery without surgery.
• Mental health: 2-3 times higher risk of depression and anxiety disorders.
• Life expectancy: morbid obesity shortens life expectancy by 5-10 years.

Causes — more than eating and exercise

Morbid obesity is a chronic, multifactorial disease. The simplified idea of 'just eat less and move more' underestimates the biological, hormonal and environmental factors involved.

Genetics explains around 40-70% of individual risk. People with certain gene variants (FTO, MC4R) have increased appetite and a lower satiety response — the same calorie intake produces more weight gain in them.

Hormonal factors: insulin resistance, leptin resistance (the satiety hormone no longer works), raised ghrelin (hunger hormone), and — in women — hormone fluctuations around puberty, pregnancy and menopause.

Medication effects: antidepressants (SSRIs, mirtazapine), antipsychotics, corticosteroids, beta blockers and insulin can themselves cause 5-15 kilos of weight gain.

Social and behavioural: stress, lack of sleep, the food environment, socio-economic factors and eating disorders (binge eating) all play a role.

The practical implication: morbid obesity is not a matter of 'willpower'. Effective treatment requires medical-biological and lifestyle interventions at the same time.

Reimbursed care in the Netherlands

In the Netherlands, with morbid obesity you are entitled to reimbursed care from basic health insurance. The route goes through your GP.

• Combined Lifestyle Intervention (GLI): 2-year multidisciplinary programme — lifestyle coach, dietitian, physiotherapist. Fully reimbursed after GP referral.
• Wegovy (semaglutide): reimbursed at BMI ≥40 (or ≥35 with comorbidity), after a prior GLI or equivalent lifestyle programme of ≥12 months without sufficient effect.
• Mounjaro (tirzepatide): partly reimbursed from 2026 with conditions comparable to Wegovy (check current status, conditions change).
• Bariatric surgery: reimbursed at BMI ≥40, or ≥35 with comorbidity, after conservative programmes. Lead time typically 9-18 months.
• Psychological support: for eating disorders or mental comorbidity, via your GP to mental health services (GGZ).

GLP-1 medication as a treatment option

GLP-1 receptor agonists are a game changer in the treatment of morbid obesity. Their effectiveness approaches that of bariatric surgery, with considerably lower risks and reversibility.

Trial results: Wegovy (semaglutide) gives on average 15-17% weight loss over 68 weeks. Mounjaro (tirzepatide) reaches 20-22% in the same period. In people with morbid obesity we see comparable or even greater absolute reductions in kilograms.

Benefits specific to morbid obesity: significant improvement in blood pressure, lipid profile, glucose regulation and sleep apnoea. Many patients can taper diabetes or blood pressure medication.

Practical consideration: GLP-1 is long-term (often lifelong) use. Stopping typically results in 60-70% weight regain within 12-18 months. This is not a 'course of treatment' — as with surgery, it is a lifelong adjustment.

At Go Leaner: patients with BMI ≥40 can be treated via an off-label or reimbursed route. A BIG-registered doctor assesses suitability and contraindications (such as MTC in the family or a history of pancreatitis), and draws up an individual plan.

Bariatric surgery

Bariatric surgery is a surgical reduction or rerouting of the gastrointestinal tract. The most commonly performed procedures in the Netherlands are the sleeve gastrectomy (80%) and the gastric bypass (15%).

Sleeve: 70-80% of the stomach is removed, leaving a banana-shaped tube. This results in greatly reduced stomach capacity and lower ghrelin production. Weight loss typically 25-30% of starting weight.

Bypass: a small stomach pouch connected to the small intestine in a Y-shape, with part of the intestine bypassed. This results in restriction and reduced absorption. Weight loss 30-35% of starting weight.

For whom: BMI ≥40 or ≥35 with serious comorbidity, after insufficient effect from conservative treatment. Reimbursed via basic health insurance after a pre-bariatric programme of 6-9 months in a specialised centre.

Risks and consequences: lifelong vitamin supplementation, regular blood tests, risk of dumping syndrome, gallstones, anaemia. Surgical mortality is low (<0.5%) but revision or complications occur in 10-15%.

Comparison: medication vs surgery

In morbid obesity, the choice between GLP-1 medication and bariatric surgery is an individual decision. Both have their place.

• Weight loss: surgery 25-35%, GLP-1 15-22%. The lead of surgery is narrowing with the arrival of retatrutide (expected 24%+ in 2026/2027).
• Reversibility: GLP-1 is reversible (stopping is possible). Sleeve is not reversible; bypass is technically reversible but rarely reversed.
• Risk: surgery carries short-term risk (anaesthesia, leakage, embolism). GLP-1 has a manageable side-effect profile.
• Lead time: GLP-1 starts within weeks of intake. Surgery has a 9-18 month preliminary programme.
• Lifelong adjustment: with both. With surgery, supplements are mandatory; with GLP-1, continued medication.
• Costs: surgery reimbursed when indicated; GLP-1 reimbursed when criteria are met, otherwise at your own expense.

Step-by-step plan: from GP to treatment

Step 1 — GP consultation: discuss your BMI, comorbidities and treatment wishes. Request blood tests and a sleep apnoea screening if not already done.

Step 2 — Referral: your GP can refer you to GLI (primary care), an endocrinologist/internist (medication), or a bariatric centre (surgery).

Step 3 — Preliminary programme: for surgery, a 6-9 month multidisciplinary preliminary programme. For medication, it is sometimes possible to start directly at a specialised clinic such as Go Leaner.

Step 4 — Treatment: medication is titrated up over 16-20 weeks to the maintenance dose. Surgery follows after approval by the multidisciplinary team meeting (MDO).

Step 5 — Lifelong follow-up: annual check-ups, blood tests, progress reviews, weight-maintenance protocol.

Mental health

Morbid obesity and mental health are closely linked. Depression, anxiety disorders and eating disorders (binge eating disorder) are 2-3 times more common.

Stigma and discrimination are real: what is called 'fat shaming' frequently occurs in healthcare, at work and in social settings. This increases stress and makes healthy behaviour harder.

For treatment this means: psychological support before, during and after weight loss is proven effective. In eating disorders, referral to specialist mental health care is indicated.

With rapid weight loss — through medication or surgery — identity issues, changes in relationships or even an increased suicide risk can occur. Psychological guidance should be a standard part of the programme.