nope. muscle is inefficient at staying warm. even worse at altitude. and a poor source of energy compared to fat.
you guys need more time reading and less computer time. both statements are dead wrong. dru- muscle tissue is what generates heat, not fat. the reason you feel cold is oxygen level in your bloodstream.
staying warm is not related to your total body mass. off course a smaller person will radiate heat faster, but it will also warm up faster with movement. this first statement is soooo bs. now why would you need a big pack in the mountains anyway? with modern gear your gear should not go over 35lbs anyway. sorry pal, but i can tell you have never been on a harder pitch (12 and up). bacause if you climbed such stuff you'd know that your forearms is what goes first. higher the body mass harder your forearms work. both of you need to freshen' up on some basic physiology and excercise physiology. werd
If you have 5% body fat where is the energy going to come from to warm you up? Probably from burning muscle. Whereas if you have a higher fat content you can burn fat to stay warm and keep your muscles strong.
Training for altitude? Cheeseburgers