I know that low carb diet cause a depletion in glycogen stores that can make muscles appear flat. How much do you need to carb up or refeed to replenish glycoden stores? or in other words get that firmness and fullness back.
Its different for every one size dependent how depleted you are. They say a good sing is eat carbs, load and pay attention to how you look, once you start get the flat/puffy stop. Of course will need to be pretty lean for this