Some new medications in development are also trying to solve for a persistent side effect of existing drugs: Patients who lose fat also tend to lose muscle. This can be particularly dangerous for older adults because it makes them more likely to fall and can worsen osteoporosis.

Novo Nordisk’s new weight-loss drug helped patients lose even more weight on average than its current Wegovy blockbuster treatment, an early-stage trial showed, as the drugmaker races to develop the next generation of obesity medicines.