I'll never turn away some ice cream, but you better believe I'll tack on another 10 miles to my next ride.
But anyway, the biggest help I've found to dieting, is to keep a set of measuring cups/spoons around. I measure most of my meals, not only to help with portion control, but also to give me a better idea of what I'm putting in my body. At 6' and 157 lbs., I'm right at where I want to be, but I definitely don't want to get any heavier than that – I've worked too hard to get to where I am. I look at food labels all the time and I definitely have a good idea of how many calories are in every single meal I eat, and whether it's a bowl of ice cream or a green salad, I find room for it in my daily diet.
However, one thing that's really heartbreaking is to see how much a 1/2 cup of granola is, and how many calories that 1/2 cup contains.