These drugs are often grouped under the label GLP-1 medicines because they mimic hormones released after eating, helping people feel fuller and less hungry. At a time when more than 1 billion people worldwide are living with obesity, these medicines are widely viewed as among the biggest advances in obesity treatment. For decades, researchers and clinicians have warned about yo-yo dieting, the repeated pattern of losing weight, regaining it and trying again. PlayFor healthcare professionals, GLP-1 treatment may be best understood as a window of opportunity. This brings attention to a part of obesity treatment that can be crowded out by excitement about new drugs: sustained behaviour change.