New terminology

That means you have to weigh 187.5 lbs (85kg) to get the full 15 lb (6.8 kg) allowance. Perhaps, one should be allowed a bit extra pack weight if one isn't hauling excess body weight. Smaller people need less food, controlling for other factors, so perhaps they should be allowed further additional pack weight. No?

That is one way. Do not forget that that is BASE weight.
Food, fuel, water (other consumables: bug dope, AM drops, etc) usually represent 1/2 to 2/3 of my PACK weight. By those figures, I could carry up towards 45# of PACK weight. Really not a bad number for a two week trip.
Did you all miss the distinction? BASE vs PACK weights, that is.

Tent/tarp (1#), Sleeping bag(1#13), pack(9oz), cooking gear(31oz, pad(10oz), clothing (long johns(14-18oz), socks(8oz), jacket(12oz), raingear6(oz) and dittybag(1#) come up to about 9-11 pounds.

"If I gained a hundred pounds of body weight, I could take more heavy luxuries."

Given that it's the lesser of the two numbers, gaining a hundred pounds would only help if you weigh 87.5 pounds or less.

That's only a pound and a half difference fro me.

>"Smaller people need less food. . . "

Hartley: True, that.

Smaller people need less food and need less surface area covered with clothing, but (1) clothing area only scales with area, not volume like weight does (giving a weight/weight advantage to larger people) and (2) big people run warm (really big people are in shorts all winter) so they further save on daytime clothing and nighttime sleep systems.

If someone needs a universal standard, perhaps that weight which reduces you daily mileage by 25% for UL and 10% for SUL. Consider that traditional BP weights reduce many people's daily mileage by 70% – compared to a no-weight dayhike of 20 miles, they might do 6 mile days with 50 pounds on their back.

Who needs a universal definition – HYOH. But the concept of "How far do I want to hike in a day? Therefore, I'll reduce my base+food+fuel to XX." is a useful one for some, especially for through hikers.

One of the best explainations of BASE WEIGHT I ever heard was a backpacker trying to explain it to a newbie girl. He said, "Imagine you'e going on an overnight backpack of 10 miles in and 10 miles out."
"Then Imagine a 7 day trip of 8 to 10 miles per day. What gear would you take on the 7 day trip you would not take on the overnighter?"

The newbie girl agreed she would take pretty much the same gear and the only difference would be food and fuel.

The experienced backpacker then told her, "So all that gear, minus water, fuel and food, is your base weight. Think of it as 'Gear Weight' ". With the term "Gear Weight" she suddenly got it and the next day they began a discussion of "skin-out" weight. Discussions like that on the trail is so much more meaningful than at home. Makes you really think about "necessities".

I have already addressed this issue definitvely:

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=23394

You have to get through a long discussion, though. The fun starts on the second page. :)