Heat affects fats when using them for cooking, but I have never heard anything about proteins being altered through heat.
I think it looks somewhat normal to stall or we even gain some weeks; I know I have, and my coach stayed at the same weight for 3 weeks and lost two clothing sizes.
It's VERY frustrating when you work so hard to stay OP. I think you're doing it right and woudlnt' worry about the heat, just stay OP and you'll get there like the rest of us.
Everything...is a choice
"If hunger is not the problem, eating is not the solution"
Start weight: 175, 5'7" tall. Goal Weight: Feeling Great! about 140.
WI#1: -9.6 Week 2: -2.6 Week 3: -1.0 Week #4 -1.0 Week #5: -3.2