Contrary to popular opinion, most complex carbs aren’t as “fattening” as you would like to believe. They may cause an insulin release (if you chose shitty an unprocessed carbs in very large amounts, ie the average American), meaning you sure as hell aren’t going to be losing fat. Nevertheless, you’d be suprised about the body’s natural gylcogen reserves-- the brain uses about 100g carbs a day to simply function!
Nevertheless, the take home message is that most of the carbs will go to fill up reserves, which in your case (at that carb level) are probably relatively empty. Also remember that complex (ie non sugar), carbs are very thermic-- and require a great deal of energy to break down. The main problem with high carb diets is that in the presence of high fat levels, they really pack on the pounds. Because of the of elevated insulin, fat unfortunately also gets “shuttled” into adipose tissue, not muscle or liver glycogen. This is why high starch diets are great for building muscle (a happy muscle is a full one) but also terrible for those who do not watch fat intake (dirty bulk).
I’m curious as to where you got your information. I’m not trying to disrespect you, just some info that I’d be interested in myself.