I remember years ago the standard was that the total pack weight should be between 1/4th and 1/3rd of your body weight. Nowadays, my total pack weight sits between 1/6th and 1/7th of my body weight (160-170lbs depending on how many Baconators I've had that month). Best I've managed for an overnighter was 1/11th of my body weight, but I currently wouldn't be able to pull that off for more than a two nighter, and given that I like certain luxury items don't really want to.