Gaining weight alone won’t give most people abs. This is only going to work for guys who have small, weak abs but very low bodyfat. These are relatively few and far between – it’s not a good strategy for most people. Rather, gaining weight can be great for building abs before cutting back and getting leaner. This cut and bulk process is common in bodybuilders for building serious size.  Weight-gain alone won’t give you abs, but you can maintain abs throughout a bulk with proper balance of calorie surplus, proper macronutrient intake, and smart training.