"You guys need actual measurement sizes like men's trousers are here in the US. 36x34 jeans always have a 36 inch waistband and a 34 inch inseam."

Exactly the same in the UK, mousethief (although I always wonder what kind of beanpole could possibly have a 36" waist and 34" inside leg - some kinda matchstick-man?).

But I think pfr is looking for something akin to what we call 'joggers' - loose-fitting, soft, stretchy material with either an elasticated or drawstring waist. They come sized in (usually) S, M, L, XL OR XXL - I guess because the stretchy waist has plenty of 'play' in it, so couldn't really be described in inches.

pfr - I, too, used to be over 17st with a 46" waist, but long-term illness and inactivity made me lose over 6 stone and drop to 36" waist! I always found M&S's joggers were generously-sized, but they might not be exactly what you're after.