everything cathex said is correct...the thing with the chocolate bar is crazy! why would you even eat chocolate 30 mins before a workout? the reason you feel less energetic is that the sugar in the chocolate bar spiked your insulin and then a half hour later you are coming down from the rush of sugar which makes you feel lethargic...carbs absolutely are the body's preferred source of NRG they are the easiest to utilize for NRG also, the human body is still very old fashioned in it's preservation mechanisms-your body sees huge muscles as a liability, they require a lot of nutrients to keep up (it's like the gas that goes into a huge V8 engine) fat requires very little if any nutrients to maintain and if your body thinks that it is starving, which low carb diets can do, your body WILL start to break down muscle... low carb diets are absolutely useless if someone is trying to build muscle...you have to have ample nutrients (carbs included) so that your body knows it is a good condition to build muscle...now the guy that is diabetic...you should be careful with carbs, I would ask your doctor what he recommends (tell him you are using AAS, which you should have anyway because they can heighten sensitivity to insulin) as to the chocolate bar guy...what does your diet look like? both with carbs and now without? the only thing I can think of is that with the low carbs your insulin levels are more stable, but this is also true when you eat complex carbs, not chocolate bars