What could be the cause of upper cheek volume loss?

Potential causes for volume loss in the upper cheeks? They are quite deep and visible in nearly every light (I am only 20). I first noticed them about 4 years ago. I lost weight at 12 due to illness, but have since put that back on, and the dents weren't visible at then. Can braces cause this? Too much sun or sugar? Hormonal imbalance? Lack of exercise? None of my family seem to have these marks either. If I were to lose ten kilos over four months now, would that further accentuate the issue?