I hear a lot of mention of carb-ups just as a necessity as a magical kickstart to get your metabolism back in check and I saw a couple of posts involving Leptin, but I really think those two things need to be tied together. If your bodyfat percentage is relatively high 20-25% and higher, your fat stores are producing more leptin than people with lower bodyfat percentage, you do not need to carb up as often or as long when your bodyfat percentage is that high. It is only when you start losing bodyfat that you have to consider making carb-ups more frequent, and lasting for a longer time.

The reason high-gi carbs at least at the beginning of a carb-up are ideal is because leptin is affected and responds much better to high-gi carbs than it responds to starches. Also leptin does not ONLY respond to carbohydrates, it responds to an increase in overall calories and fat storage, it is just that the quickest way to get there is with high gi carbs, and since you can fill once glycogen store with 4 grams of water, you're gaining water weight mainly and not fat, which can be quickly depleted by intense work-outs and returning to a low-carb diet after the carb-up, with the added benefit of the increase in leptin which tells your body that it is being well fed and basically makes fat more readily available for use as energy instead of trying to hold on to it.

Unfortunately when the intellectual bodybuilder community explains these things they like to do it in a way that most people can't understand, so people know it works but really not why.

Bottom line, the leaner you get the more often you need to carb-up, some body builders with very low BF percentage carb-up every other day.

There is a real promising supplement coming out by avant labs called leptigen that is supposed to tell your body it is being well fed thus allowing you to continue low-carbing without the carb-up and other benefits of increased leptin.



Lep