Increase hair loss from dieting?

Dear Group -- I'm 26 years old, and I had began taking propecia 5 years ago. This helped w/ my hair loss. HOWEVER, just recently my hair started falling out like leaves in fall.. I haven't seen it fall out like this since i began taking propecia.. My only thought is that i'm dieting. But it's not the first time i dieted. Has anyone experienced the same? i.e. started taking propecia and everything was fine. And all of a sudden everything regresses back to its original state.. Has anyone lost hair from dieting. Any advice would be great. Thank you in advance. --R