Protein!!!!!!!!!!!!!!
You can try things like soy crisps between meals - they came in many flavors and can be found in all the major supermarkets (mostly in the organic/natural section). The South Beach meal replacement bar is also pretty good, it has 19 g of protein and very little, if any, sugar. (BTW, I've been eating protein bars since about 2 months after surgery and have never had a problem, but check with your surgeon to make sure). There is a product called Any Whey that you can get at GNC, it is unflavored protein powder that you add to yogurt, pudding, soups and other recipes. I use it to make peanut butter balls (1 cup natural PB - I use crunchy, 1 cup old fashioned oats, 1 scoop unflavored protein powder, 1/4 cup Splenda...mix all together and roll into small balls, store in fridge) and I used to put it in oatmeal and yogurt when I was newly post-op. Kashi Go Lean cereal is high-protein, low sugar, and can be eaten dry as a snack. Also, edamame (soy beans) are a good source of protein. I buy the shelled ones in the refrigerated section of Whole Foods, but they are in the frozen section of most markets.
Hope that helps!