Roughly a third of bariatric patients shed hair between months three and six. It is telogen effluvium, it is temporary, and a transplant then is the wrong answer.
Hair grows in cycles, and roughly nine follicles in ten are in the growing phase at any given moment. A general anaesthetic, surgical stress and a sudden calorie deficit push an abnormal number of them into the resting phase simultaneously. Two to three months later those follicles let go together, which is why shedding starts around month three, peaks near month five and looks alarming in the shower. It is diffuse across the whole scalp, not a receding hairline.
Protein below sixty grams a day, ferritin under thirty, low zinc, low vitamin D and low B12 all prolong the shed and make the regrowth thinner. This is why the protein target is not a suggestion and why blood work at three, six and twelve months is part of the programme rather than an extra. Correcting ferritin in particular changes the trajectory. Supplements alone will not rescue anything if daily protein intake is still twenty grams short.
Our hair department charges €1,800 for sapphire FUE and carries a lifetime growth guarantee, and it would be easy to sell that to someone frightened by a hairbrush. We refuse, for two reasons. During an active effluvium the pattern is unreadable, so nobody can design a hairline honestly, and the shock loss that follows any transplant would add to the shedding already under way. We ask for stable weight, normal blood work and a minimum of twelve months.
If the hairline is retreating at the temples or the crown is thinning in a defined pattern, that is androgenetic loss which the surgery merely unmasked, and it will not reverse on its own. The same applies if shedding continues past twelve months, or arrives with fatigue and cold intolerance, in which case thyroid function is checked first. PRP at €600 has a maintenance role, but only after the deficiency work has been finished.
In a straightforward effluvium, density returns close to its previous level between months nine and twelve, provided protein and iron have been corrected. Hair that was already thinning genetically does not come back.
Hitting the protein target helps and a slightly gentler deficit can help. Abandoning the plan trades a temporary shed for the problem you had surgery to solve, which is a poor exchange.