What is the best donor place for a fat transfer to the under eye to avoid future hypertrophy?

We usually use inner thighs as an excellent donor site for fat grafts when performing facial fat grafting. Larger quantities of fat grafts may need other sites. Good luck.

We routinely use fat transfer to the cheek/ under eye area when performing lower eyelid surgery. In women we take the fat from the outer thigh and in men from the tummy. It is only a very small amount of fat that is taken and you won't notice it has gone. Typical amount of fat injected into the under eye area is around 5-8ml on each side.
The last thing I would be concerned about is future hypertrophy of the injected fat as you will lose upto 50% of it and will wish you had more!

Fat that survives the grafting process will grow with weight gain. The host source is fairly irrelevant.
Of all the things to be concerned about with this procedure where the fat is harvested from is probably not one of them.
There are really only two variables determine the success of cosmetic surgical procedures. The first is the individual candidacy of the patient and the second is the skill and experience of the provider.
These are probably equally as important.
Grafting fat is fickle, unpredictable and technically difficult.
Survival of fat is highly dependent on the host tissue available to support the graft probably even more so than the actual grafting technique.
Thickness of host tissue varies quickly in adjacent areas around the orbit. for this area fillers unlike fat is highly predictable, precise and far more forgiving.
Best,
Mats Hagstrom MD