I was told by my nutritionist that if you're REALLY craving something that's crispy and chip-like, she suggested pork rinds since they're 99% protein. She said not to overdo it but would be a good alternative to chips and such. they're not exactly "healthy" because they're deep-fried, but are better for you than potato chips.
I'm scheduled for my surgery in two days, so I'll see how I do. Currently in the pre-op liquid diet, and Boy Howdy am I missing snacks in the evening. Especially if I'm watching a show or movie. I crave that popcorn!
Don't be hard on yourself. If you have a bad day that you cheated or had some sugary or high-calorie food, just think that tomorrow is a new day and a new day to be "good".
Hope this helped a little.