The reason you are getting leaner as you say from cutting milk and bread is simply reduction of calories.
I would say it better to cut down on your dextrose and have something with some nutrition like milk pwo. This would also cut calories even more...2 cups of milk, 16 gr. protein, 22 carb, and 160 calories.
80 gr. of dextrose....320 empty calories. You make the choice.
****I would like to add to this that another ideal choice is simply your next scheduled meal. Take some BCAA's while training(mixed opinions on these, but this is due to the fact that folks use them for the wrong purpose, and don't SEE any gains...they are best utilized when dieting. They are metabolized directly by the muscle, so they are easily burnt for fuel. This will spare lean mass when dieting well), then go home and have your next scheduled meal. I would make this one a good protein/carb/fat meal. I am fond of mixed meals anyway.
I do this above when dieting for contests all the time.