J Health Behav Med Hist 2026-4.
Without a behavioural expert, a weight-loss drug will not work
Robert C. van de Graaf, MD, director
MEDTCC Institute for Health, Behaviour, Medicine and its History, The Netherlands
Anne Roefs, PhD. Professor of Psychology and Neuroscience of Abnormal Eating.
Faculty of Psychology & Neuroscience, Maastricht University, The Netherlands
In the debate on weight-loss medication, a development has been normalised that is deeply troubling: an organ that is central to obesity is being treated on a large scale by physicians who are not trained to do so. The fact that millions of people may need to use this medication for life makes this painfully clear. Not as a medical success, but as evidence that a complex and vulnerable organ is structurally being treated under the wrong leadership.
The substantial relapse after discontinuation of medication and the prospect of lifelong use are not accidental side effects. They reveal what happens when an organ is manipulated without being truly understood or restored. This is not a failure of patients, nor proof that the medication does not work, but a systemic failure in how we approach obesity.
Obesity does not primarily arise in adipose tissue, the pancreas, or the gastrointestinal tract. It develops in what we might call the behavioural organ: the integrated system in which motivation, reward, stress regulation, impulse control, habit formation, and environmental influences jointly steer behaviour. This organ determines not only what someone eats, but also how they respond to stress, temptation, social pressure, and recovery after relapse. It is learnable and adaptive, but also vulnerable to dysregulation. It is precisely this organ that is now being influenced on a large scale by medication. That is not inherently wrong. It becomes problematic when this intervention is detached from behavioural-medical governance. An organ that organises behaviour cannot be sustainably restored without diagnosis, guidance, and long-term retraining.
In medicine, a fundamental principle applies: the lead clinician is specialised in the organ being treated. A cardiologist does not perform brain surgery; that responsibility lies with a neurosurgeon. An occupational physician does not remove a bowel tumour; that is done by a specialised surgeon. This principle is not a formality, but a basic condition for quality of care and patient safety.
In obesity care, this principle is being abandoned.
Internists, surgeons, cosmetic physicians, and increasingly newly qualified doctors prescribe medication that profoundly interferes with the behavioural organ. This increasingly happens outside regular healthcare, via commercial platforms offering ‘medical weight loss’ as a service. Physicians often act with sincere intentions and follow guidelines or continuing education. But behavioural-medical expertise cannot be replaced by a course, a protocol, or a guideline primarily developed from the perspective of other organs, such as adipose tissue.
Behavioural medicine is a specialty. It requires knowledge of behavioural diagnostics, learning processes, stress and reward systems, contextual influences, relapse mechanisms, and long-term behaviour change. Without this expertise, the complications of the behavioural organ largely remain invisible: loss of self-regulation, dependency thinking, avoidance behaviour, declining resilience, a shift of responsibility from person to product, and dysregulation of stress and reward responses. These are not abstract concepts, but real, long-term consequences that undermine functioning, work, relationships, and health.
The well-known yo-yo effect after stopping weight-loss medication is the most visible signal of this. Weight returns not because individuals fail, but because the behavioural organ has not been restored. That millions of people may require lifelong medication is therefore not proof of effectiveness, but proof that the behavioural organ has structurally remained out of view.
The conclusion is therefore unavoidable: physicians without behavioural-medical specialisation cannot be the lead clinicians in problems of a dysregulated behavioural organ. As with any complex condition, clinical governance belongs with the specialist. Other physicians can support or contribute, but not lead.
If the idea of lifelong weight-loss medication teaches us anything, it is this: obesity does not require ever more powerful drugs, but better governance. Governance that does justice to both the vulnerability and the capacity for recovery of the behavioural organ. And that begins with recognising it as a fully recognized centre of treatment.
Translation from: Zonder een gedragsdeskundige gaat een afslankmedicijn niet werken (Trouw)