I am a little confused about the fact that some people say to look at fat content rather than calories in foods. If I want to gain healthy weight, is there any difference in whether the food is calorific with a lot of fat or calorific with little fat and more protein? Maybe the protein thing is for building muscle mass. Should I be looking at calories alone if my sole purpose is to gain some weight?
If your sole purpose is just gaining weight, then yes, the only thing that count is calories in vs calories out.
Fat will not supply you with the building supplies you need to gain/build more muscle (i assume you want to gain weight in the form of muscle not fat).
Yeah you need high calories but you also need lots of protein to gain
Most body builders will suggest you eat your weight in protein a day. ie If you weigh 150# you should eat 150 grams of protein a day. So eat lots. and fequent meals are best and lift heavy!
Calories in and calories out. At least 2500 if you're a sedentary female. More if you work out.
It's good to get proper nutritional balance, though, and usually for a gainer that'd be around 55-60% carbs, 10-15% protein and 25-30% fats. 30% fats solid if you don't have your period.

Figure out what type of eater you are and you might just find the answer to permanent weight loss.
Take the Diet Profile Test and learn to avoid the pitfalls and self-sabotage that often come with your personal profile.
