i've mentioned this several times here - years ago - I went on some crazy fad diet (and lost quite a bit of weight which regained when i started eating normally again) the diet was virtually no fat and very low protein... this diet caused my hair to fall out in clumps...
And my very thick head of naturally wavy hair all of a sudden wasn't so thick anymore and over 15 years later, it never really recovered - though now I just blame aging...
It's something I would mention next time you're at the doctor, to make sure that tehre's no underlying medical condition causing it (yes, that's my standard response to any changes in your body's behavior that's out of the norm) but i would also look at your diet and check your fats and protein level and make sure that they are in good proportion to the rest of your calories.
