Chatnoire, I am just like you; in my head I start thinking I'm reacting to walnut or almond butter, so I stopped eating it! I *do* use soy nut butter, but only a certain brand, called Simple Foods. It's made locally here in MA, but you can order it on line. It's made my life a lot easier when I have to take a sandwich on a ride. And, it tastes good. I eat a lot of nuts, though, and they really have helped me maintain my weight loss.
I also lost a lot of weight when I started riding. I had been thin, at the same weight for many years, when I started gaining and getting burned out on the exercise I was doing previously about 2 years before I started riding. I wasn't huge, but about 15-20 pounds heavier than I am now. It was not boding well for the future. I've been able to maintain this for 10+ years, but it's only been recently that I've gotten below my "set point" and I seem to have reset my body by changing my eating habits a bit. For me, it's all about upping the protein and limiting the carbs, especially white flour products. I won't say I never eat it, but, it's pretty limited.