Weight regain after treatment or surgery

Is it common?

Yes. Obesity is a chronic disease that tends to recur¹, and some of the weight lost can be regained after a support programme, a medicine or surgery. After surgery, weight loss is generally better maintained, but not for everyone: more than ten years after the operation, most people maintain substantial weight loss, while others regain part of the weight they lost^{2, 3}.

When should you seek advice?

If your weight is going back up and this worries you, you can seek advice without waiting for any particular threshold. The earlier weight regain is addressed, the more options there are.

Why does weight go back up?

There are often several causes, and willpower is not the issue. The assessment looks for them with you, without judgement, for example:

• a biological adaptation: after weight loss, the body tends to defend its previous weight, and hunger may increase;
• changes in daily life (diet, sleep, activity) or a medicine that can contribute to weight gain;
• a difficult period, whether personal, professional or health-related;
• changes in eating behaviour, or alcohol use;
• after surgery, an anatomical change, investigated with specialist tests.

What can be done?

Depending on the causes identified, the assessment may lead to:

• more intensive support: medical, dietary, psychological and physical activity. This is the first step, whatever comes next;
• medication, which can be discussed: see Medication;
• a specialist anatomical assessment (endoscopy or imaging), if you have had surgery;
• in certain situations, revisional surgery, discussed by the multidisciplinary team and with you. It is never automatic; it is more complex than a first operation and is carried out in a specialist referral centre⁴.

Medication and surgery can also be combined within the same care pathway: see Medication and surgery: complementary approaches.

If you have never had an operation, weight regain after several treatments that were properly carried out is one of the situations where an assessment with a view to surgery can be useful. The choice depends on the causes identified and on what you want.

Frequently asked questions

I have regained weight and I don’t dare come back: what should I do?

Come back. Weight regain is part of how the disease can evolve; the team is there for exactly this, without judgement, even if your follow-up stopped a long time ago.

What next?

Whether you had your operation at the Centre, elsewhere in Switzerland, abroad or not at all, you can request an appointment to review your situation. If you had your operation elsewhere, your original centre remains the first choice where possible; the Centre can also give you a second opinion. Your request is received by the Centre’s appointments team, who will organise the next steps with you. If you have had an operation, please mention it in your request (see You have already had surgery).

Medical review of the French version: Dr Pierre Fournier

Scientific sources and references

Sources accessed on 12 October 2026. Reimbursement rules and information on medicines change over time.

1. Gerber PA, Collet TH, Favre L, et al. Swiss obesity clinical practice guidance. Swiss Med Wkly. 2026;156:5415. View source
2. Kraljevic M, Süsstrunk J, Wölnerhanssen BK, et al. Long-term outcomes of laparoscopic Roux-en-Y gastric bypass vs laparoscopic sleeve gastrectomy for obesity: the SM-BOSS randomized clinical trial. JAMA Surg. 2025;160(4):369-377. doi:10.1001/jamasurg.2024.7052. View source
3. Adams TD, Davidson LE, Litwin SE, et al. Weight and metabolic outcomes 12 years after gastric bypass. N Engl J Med. 2017;377(12):1143-1155. View source
4. Swiss Society for the Study of Morbid Obesity and Metabolic Disorders (SMOB). Directives pour le traitement chirurgical de l’obésité, in force from 1 July 2023 (in French). View source