It hasn't been that hard for me because I have always fed my babies healthy foods. My DD is 13 months and there isn't anything that I feed her that I wouldn't eat myself (or that wouldn't fit in my plan somehow) except for the formula. (We're still doing formula for a few months because I planned on breastfeeding for at least two years but it didn't work out and it seems wrong to take away that substitute so soon.)
One thing that keeps me from eating too much during the day is the baby gate! I have a baby gate to keep DD from the kitchen and it keeps me out, too. Sometimes I'm just too lazy to climb over that thing. My problem is eating too much after the baby gate comes down when the kids are in bed.