Why do people of higher body weight burn more calories?

Why do people of higher body weight burn more calories? Why do people of lower body weight burn less calories? Shouldn't they burn more calories since they have less body fat (probably) and body mass index? This is what I'm talking about: http://www.mayoclinic.com/health/exercise/SM00109

Public Comments

1. Let's just consider walking. What is this activity? You are carrying your entire body weight with your legs as you walk. If you weigh more, more energy is require to move a larger weight, and this is achieved by burning more calories. A smaller person is moving less weight, therefore fewer calories burned.
2. Maybe they burn more calories because it takes a lot more energy for them to move around...If you would like to burn calories faster, lift weights. By increasing your muscle mass, you will burn calories faster. Be sure that you consume enough protein to keep up with your muscle gain.