Appetite - I am on Clonazepam 0.5 take 1/2 3xday will it make me gain weight?

It depends on your genetic makeup, your response to the drug, height/weight, and metabolism.

I've been on Clonazepam for over a year and have had no change in my body weight.

Weight changes are side-effects in benzos because for some people, they cause nausea as a side-effect, thus reducing appetite. In others, they cause tiredness/sedation which leads to less exercise, which can cause weight gain.

The drug does not directly affect metabolism like Antipsychotics (Zyprexa, Saphris, Geodon, Risperdal, Latuda, Seroquel, Invega, and Abilify) or Triptans (used for migraines, and include Imitrex, Maxalt, Frova, Relpax, and many others).