I workout in the evenings too and I've taken in 40 g of dextrose post-workout during contest prep, and even rice after that on my refeed days, and it didn't hinder my fat loss in any way. Your body needs carbs immediately post-workout and you'll benefit from an insulin spike regardless of the time of day. Immediately pwo I'd take in simple carbs, then some complex carbs another 45 minutes to an hour later.