Japan Obesity Society Warns Against Misuse of Diabetes Drug Mounjaro for Weight Loss

The Japan Society for the Study of Obesity has issued a statement cautioning against the misuse of Mounjaro, a drug approved for the treatment of diabetes, warning that it should not be used for rapid weight loss or extreme dietary restriction.

Mounjaro, which helps regulate blood sugar levels, has also been found to cause significant weight loss as a side effect, making it attractive to people seeking to shed pounds quickly rather than manage a medical condition.

According to media reports, including coverage from Yomiuri Shimbun and NHK, an increasing number of young people and foreign tourists in Japan have obtained the drug specifically for its slimming effects, despite it not being officially approved as a weight-loss treatment.

One account described a user who continued taking the drug even after experiencing hair loss, illustrating the lengths to which some individuals are reportedly going in pursuit of rapid weight reduction.

NHK reported that this trend of misuse has resulted in several cases requiring emergency transport by ambulance, as patients experienced adverse reactions linked to losing weight too quickly.

Medical experts have long cautioned that sudden, extreme weight loss can place significant strain on the body, potentially triggering complications such as nutritional deficiencies, muscle loss and cardiovascular issues.

In its statement, the obesity society emphasised that Mounjaro is a prescription drug intended for patients with diabetes under medical supervision, not a general-purpose slimming aid for the public.

The society is urging healthcare providers and the public alike to ensure the drug is used appropriately, recommending that anyone considering it for weight management consult a qualified doctor first and avoid attempting drastic, unsupervised weight loss.

This development reflects a broader concern in Japan regarding the off-label use of diabetes and obesity medications for cosmetic purposes, a trend partly fuelled by social media and growing international interest in weight-loss drugs. Off-label use means taking a medicine for a purpose it was not officially approved for.

Authorities and medical bodies are expected to continue monitoring the situation, as the popularity of such drugs for non-medical weight loss shows little sign of slowing, both within Japan and internationally.