I don't think having a large RM makes you hungry during the day. My RMs are always huge compared to my CMs, but I'm never hungry during the day.

It's more likely that something that you're eating at your CMs is setting off cravings. I know that the Hellers are not big fans of shakes ... if yours contains and artificial sweetener, that could cause cravings ... it does in some people. Also, make sure that the veggies you eat at lunch are on the allowed list (no brocolli, snow peas, carrots) or your carb count could get above 4 and set off cravings.