since you have a hard time gaining weight, eating more quality carbs will certainly help. the carbs in those weight gainers is mostly sugar.. that's not going to help you gain quality muscle. perhaps someone more experienced with how to explain it can chime in, i just know it isn't good for you and won't help.

reading up on the diets doesnt mean 'weight loss'... its just referring to a structured meal plan, called a 'diet'. its important to know that distinction.

doing the work you do definitely will contribute to your weight gain difficulty, so eating more carbs will help with that as well. but you need more food-source protein too.

also, try not to eat too much canned tuna. i know it's convenient, but it's also high in mercury and can be toxic if you eat too much of it.

for convenience meals, canned chicken and turkey are also good quick fixes, and are pretty cheap in the grocery store as well.