Most people think of fat as a bad thing because they are trying to lose weight. But your body would really like you to know that certain types of fats are "essential" in that the body can't make them. So if you don't get enough of the right types, bad things happen. Just like you need to keep the right level and kind of oil in your car, you need to be putting just the right amount and types of oil into your body.
Basically this boils down into eating enough omega 3 fatty acids. To get started, you will want to add salmon, tuna, flax seeds, and walnuts to your regular meals. To get enough, you will want a high quality fish oil supplement that is molecularly distilled to remove anything but the good stuff. Take the supplement on any days you don't eat foods already containing 2g of EFAs (1g for women). This is the sweet spot. Don't eat more or less than this per day.
The fish oils EPA and DHA can increase muscle synthesis and decrease muscle degradation, they have been suggested to support insulin function and increase glucose and fatty acid uptake into muscle cells.
The benefits of EFAs go on and on. They have been well studied. Do your own homework and then work them into your nutrition schedule.