A small note on "were vs. was"
In this case you ought to say "were":
If you were fat, I'd still love you.
If I were fat, you'd still love me.
If I were fat, would you still love me?/Would you still love me if I were fat?
However, in spoken English this use of "were" sounds a little formal. Most natives (at least here in America) prefer to use "was".
Hope this helps.