If I so much as put on 5lbs my stamina/endurance suffers. It’s really not an either/or thing. Everyone not at the bottom can stand to loose weight. If you are not weekly in shape when you hit the mountains elk hunting, you are going to feel it. Like Brad says, ounces make pounds and pounds challenge your capability. The maturation of a backpack hunter never ends, your load out and goals change with your age, your wisdom can often defined by your gear and what you place as important.
