If those with a high metabolic rate will have a hard time gaining weight, those with a low metabolic weight will likely have a hard time

Answer : Losing weight

Your metabolism affects your BMR (Basal metabolic rate) and if you have a faster metabolism, the more you are required to eat. If you have a low metabolism, your body cannot process foods very quickly so you require less calories and have a much easier time gaining weight. Losing weight is much more difficult if you have a slow metabolism.