I was never able to gain any weight again after losing a ton of it during the time I believe I got my infection, whether it is lyme, candida, or something else. I have yet to get properly tested.
High fat did not do anything for me personally.
Since I've been back on the Anti-Candida diet, I thought I should help my digestion and help create a good environment for probiotics. I started eating raw sauerkraut everyday, my appetite really improved. I've been eating a lot more, and have also been experiencing a little more energy than usual. This was on top of a good probiotic supplement.
I have also been eating rice everyday though, which may be controversial? My naturopathic doctor told me to eat enough rice, and I've been doing just that and doing better than usual. I only eat whole grain rice from Lotus Foods, just the Forbidden and red Bhutanese rice, which seem to be much healthier than the usual.
Do you eat meat? If you can afford it, get the good stuff. On top of that, chew your food very well! Focus on it!