Why doesn't the skin always go back after losing weight?

Age helps, but it isn't everything

We need to separate people who lose weight conventionally from those who do so through bariatric surgery. Someone who loses weight at 18 or 20 has stronger collagen, will retract more and will very probably get a good result, even if not the ideal one.

After bariatric surgery, the idea that the skin goes back into place becomes a myth. Asymmetries appear in the chest, flanks, legs, arms, face and neck. Why? Because gravity pulls everything down, and because nutrient absorption after surgery directly affects collagen fibres and skin strength. It is the perfect combination for everything to fall rather than lift.

Previous degree of obesity and type of surgery

More than age, the cut-off is the degree of obesity at the time of surgery and how many kilos had to come off. That is why different procedures exist (sleeve, bypass, balloon), and it is the bariatric and nutrition team that chooses the right one according to each person's risk and comorbidities. It isn't “you have to lose this many kilos”: it's a whole picture that gets analysed.

The tent and the pole

With excess weight the skin is taut: there is a lot of fat in the subcutaneous tissue and oedema. When weight drops quickly, as happens after surgery, that tension disappears at once. It's like abruptly removing the pole that holds up a tent: the roof drops, and the ropes that should contract don't get there in time. If those ropes are also weak because of absorption, the result is skin that is left over and sags.

Is there an age limit?

There is no fixed age. In adolescents with metabolic disorders who need bariatric surgery, we generally wait for development to finish, unless there is a reconstructive need that can't wait. In older people the limit is set by general condition, not the number: I have patients in their 60s and 70s who lived with obesity all their lives and are candidates today. It always depends on comorbidities and on how each person arrives.

Why surgery is done in stages

It's very common for patients to arrive wanting everything done. I understand: after so much effort, they want to wear a swimsuit, a dress, a neckline again. But safety comes first. I divide into sectors: often the central area (breasts and arms) on one side, and abdomen and legs on the other, depending on the degree of lipodystrophy.

The question that guides me is what bothers you the most. That decides which surgery comes first.

Losing fat doesn't mean regaining tension. But you're not alone: nutrition, exercise, surgical techniques and technology are tools. This is biology, not failure.