Where we seem to get bogged down in minutia is discussing actual weight values vs. what we think characters should be able to pick up. I think it would be very difficult to create something both realistic and workable using a system largely designed to model capabilities in an abstract way. So why not abstractify weight as well? Instead of worrying about determining precisely how much a character can lift, then comparing that value to the actual weight of an object (which is something a GM often has to decide off the cuff), then (if the character isn't quite strong enough to lift that) rolling to see how much more the character can lift... we can just take a step out of that and rely on Body + Strength tests. (As far as the amount one can carry with her, the RAW are quite sufficient; you're not going to be able to lug that much with you, and imposing some sort of "encumbrance" penalties even before this limit isn't unreasonable. What we need are rules for lifting and related feats that are both more realistic and more cinematic.)
The Lift Threshold Option
Rather than your attribute ratings determining what you can lift as a strict kilogram value, your lifting power depends entirely on the hits you attain on a Body + Strength test (and so varies). This is fairly realistic, considering weight lifters aren't always able to lift the same amount each time -- their results form a range, not a precise measurement. You have the potential to exceed your lift allowance on an "average" roll by converting dice to hits (and spending Edge), allowing the occasional truly cinematic feat of strength without throwing the baseline. A poor roll means a musclemonster may not manage to lift something light, while a lucky result may let a weak character tip over a car... just as in real life, even the strongest people can strain or fall prey to exhaustion, while soccer moms hopped on adrenalin can lift cars off their howling kids.
1) Roll Body + Strength: each hit allows you to lift roughly 50 kg. Item weights are abstracted as lift thresholds, which reflect how hard they are to pick up, drag or otherwise manage. This is largely a factor of raw mass (assume a threshold of 1 per 50 kg of weight, rounded up), but an awkward item may have a lift threshold higher than its raw mass suggests; meanwhile, a handle, lever or the like can mitigate the threshold of a very heavy object. Dragging or pushing an item is usually easier than picking it up. And of course, friends always help; use the rules for teamwork. Rather than worrying about precisely how much some object weighs, GMs can "eyeball" a lift threshold based on how hard she feels it should be able to lift. Sample thresholds follow:
QUOTE
Lifting unconscious 300 kg troll ally: 6
Dragging same: 4
Helping said troll with wounded leg stand: 3
Lifting SynthOak coffin containing dead troll ally (bring friends!): 10
Dragging same: 4
Helping said troll with wounded leg stand: 3
Lifting SynthOak coffin containing dead troll ally (bring friends!): 10
2) You can convert dice on your Body + Strength test to automatic hits (up to half the pool), but you lose that amount from your pool and take one box of stun damage on the following turn for each "auto-hit": your character draws on her inner reserves and performs an amazing feat of strength, but pulls a muscle or exhausts herself. To continue holding the object up, you must make further Body + Strength checks, possibly taking damage for auto-hits. (Hope your character's Doc Wagon contract is current and paid!) Glitches on lifting tests may inflict a box of stun damage, cause the lifter to bump into an ally with the object, or create some other unforeseen result.
QUOTE
Maria, a physically "average" elf (Body 3, Strength 2) wants to move a dumpster to check the wall behind it for a secret door she thinks might be there. (Don't elves spot those on a roll of 1 on 1d6?) The GM figures the dumpster weighs at least 200 kg with all the trash in it, but Maria only wants to move the dumpster over (not pick it up), and there are handholds on the side; the GM rules the dumpster has a lift threshold of 3. Maria's player converts two of her six Body + Strength dice to auto-hits before rolling, giving four dice left in her Body + Strength pool; she'll take two stun damage on the next turn.