With GLP-1 drugs such as Ozempic, losing weight has become faster than ever for many people. But speed has brought a problem that doesn't show on the scales - it shows in the mirror. Aesthetic doctors are getting more and more questions about loose skin on the belly, arms, thighs and knees.

"The skin may not retract at the same pace at which the body's volume is shrinking," explains Dr Beatriz Beltrán, a specialist in aesthetic medicine, nutrition and anti-ageing medicine. How loose it ends up depends on several things: age, the quality of the skin before the weight loss, how many kilos were lost, how long the excess weight lasted, and how much collagen and elastin the body is able to produce.

In other words, the injection fixes the number on the scales, but the skin has its own pace. How many of those starting treatment know this before the first dose?

To begin with, the doctor recommends cosmetics with a few proven ingredients: retinoids, which stimulate collagen production; peptides for repair; antioxidants such as vitamins C and E, which protect the skin from oxidative stress; and hyaluronic acid and ceramides for hydration. They improve firmness, but they don't work miracles when the sagging is pronounced.

Movement matters just as much. "Strength training reduces the unwanted effects of losing a lot of weight," says trainer Cris Díaz. Preserved muscle mass also lowers the risk of the yo-yo effect - the lost kilos coming back.

When the sagging is pronounced, creams are not enough and professional treatments come into play. Beltrán lists three options: injectable biostimulators, such as poly-L-lactic acid, which push fibroblasts to produce new collagen; monopolar radiofrequency, which generates deep heat and activates skin renewal; and tightening lasers, such as Fotona TightSculpting, which improve skin retraction and firmness.

The point is simple and a little uncomfortable: rapid weight loss doesn't end when the scales show the number you wanted. The skin needs its own time, exercise and, often, extra treatments. It is worth asking before, not after: will the body be able to keep up?