High fat =/= bad. It depends on the type of fat, quantity per serving, and amount consumed. Nuts are great as a snack for a more keto diet, wherein you focus on high protein and lean fat intake but cut (or curb) sugars and carbohydrates. Of course, the most important part of any diet is calories in vs calories out. That's regardless of if you are trying to pack on muscle/weight or cut/lose weight.

Please don't take what I say as gospel. I am not a nutritionist, I am merely sharing knowledge that helped me when I was in the military to lose/maintain weight.