BMR is the amount of energy your body requires to function on a daily basis, not including any movement. It accounts for the majority of your energy requirements, 60-75%. This is just the energy needed to cover the basics such as lungs breathing, heart pumping, liver cleansing and brain thinking.
Ways to boost BMR:
Gain weight. The larger you are the more energy your body requires to survive even without activity therefore larger people have a higher BMR, however fat gain is not always desirable. Gaining weight through increased muscle mass will increase BMR whilst improving health markers and the shape and tone of the body.