Increased Consumption Due to High ST

[Varyon]

This is just a little something I've been playing around with as part of a new DF setting I've been working on, and wanted to see if the hivemind would like to weigh in. I'm wanting to have consumption scale with ST, which as I understand it would be realistic, but am not certain exactly how it should scale - and also, how this interacts with SM.

It seems like the ST bit should scale linearly with BL, but since you're not constantly using your muscles at near-full capacity, perhaps BL/2 would be more appropriate. It doesn't seem like a larger or smaller creature should expend any more or less energy than an SM+0 one to lift a certain weight, however, so I'm thinking this would be a constant +n kcal/day per +1 BL (which, using humans as a model and assuming 3000 kcal/day - what GURPS roughly does - works out to +75 kcal/day per +1 BL). Does that seem appropriate?

For accounting for SM, I'm just using the relationship established in Biotech (consumption is the square of scale) to establish a base consumption for a given scale, then adjusting that for ST at +75 kcal/day per +1 BL. Does this sound ballpark accurate, or am I completely off?

Yes, my version of pixies (who are ST 5, when by size they should be around ST 1.5) are going to be absolutely voracious eaters. There's a reason they are known for having done extensive research into extradimensional storage bags and the like.

[whswhs]

In my current campaign, which has humanoid races with expected ST ranging from 5 to 14, I use the simplified model that daily food intake varies with Basic Lift. A ST 10 human needs 3 meals a day; a ST 7 nixie needs the equivalent of 1.5 meals; a ST 14 troll needs the equivalent of 6 meals. However, because their stomach volumes scale with weight, not BL, a nixie needs more small meals and a troll needs fewer big meals.

[malloyd]

Originally Posted by Varyon

This is just a little something I've been playing around with as part of a new DF setting I've been working on, and wanted to see if the hivemind would like to weigh in. I'm wanting to have consumption scale with ST, which as I understand it would be realistic, but am not certain exactly how it should scale - and also, how this interacts with SM.

The units of Basic Lift x Move Rate come out in energy, and it looks fairly reasonable. Food consumption should be linear in energy. Yeah OK for warm blooded things there is a size dependent term in there too, but big warm blooded things are generally going to be strong, fast or both, so probably close enough.

[Anthony]

Originally Posted by malloyd

Yeah OK for warm blooded things there is a size dependent term in there too, but big warm blooded things are generally going to be strong, fast or both, so probably close enough.

It's mostly a problem with small warm blooded things, not big; the rate for being warm blooded scales with temperature difference * surface area / thickness of insulation, and thus at constant proportions scales with the 1/3 power of mass, which is much slower than general metabolic scaling (which at constant proportions scales with the 2/3 power of mass). In practice, large animals need extra heat dissipation so the warm-blooded factor pretty much drops to zero when active, but there's a reason the smallest known mammal is about 30mm while the smallest known vertebrate is 8mm and the smallest insect is 0.14mm.

[Agemegos]

Be aware of Kleiber's Law. Mammals' base metabolic rate scales with the 3/4 power of mass.

(There is a very interesting phenomenon in newborns in which it takes quite some time after birth for their metabolic rate to rise from that expected of a part of their mother's body to that of an independent mammal their smaller size.)

[Varyon]

Originally Posted by Agemegos

Be aware of Kleiber's Law. Mammals' base metabolic rate scales with the 3/4 power of mass.

That’s useful, if a bit frustrating (the article notes the reason for the law is unknown).

If we presume there is a creature who has strength well out of proportion to its mass, Because Magic, but that must still fuel that strength through mundane food consumption, do you feel it would be more appropriate to use the caloric needs of a larger creature with comparable strength, or some sort of average of this and what the magically-enhanced creature’s mass tells us? Note here we are assuming a rather active Pixie (as active as a human who needs 3000 kcal/day), so that enhanced strength is going to be seeing recular use.

[Anthony]

Originally Posted by Varyon

If we presume there is a creature who has strength well out of proportion to its mass, Because Magic, but that must still fuel that strength through mundane food consumption, do you feel it would be more appropriate to use the caloric needs of a larger creature with comparable strength, or some sort of average of this and what the magically-enhanced creature’s mass tells us?

Depends on the details of the magic and on how it's used. Real muscle will require food energy equal to (total work done) / (efficiency) + (resting energy consumption), but there's room for considerable variance in total work done, efficiency, and resting energy consumption.

[whswhs]

Originally Posted by malloyd

The units of Basic Lift x Move Rate come out in energy, and it looks fairly reasonable. Food consumption should be linear in energy. Yeah OK for warm blooded things there is a size dependent term in there too, but big warm blooded things are generally going to be strong, fast or both, so probably close enough.

I would recommend using Basic Lift x Basic Move. Enhanced Move isn't relevant, as it won't be sustained for long periods. But yes, the dimensions do come out to power, or energy/time: force x (distance/time) = (force x distance)/time = energy/time = power.

[whswhs]

Originally Posted by Varyon

That’s useful, if a bit frustrating (the article notes the reason for the law is unknown).

If we presume there is a creature who has strength well out of proportion to its mass, Because Magic, but that must still fuel that strength through mundane food consumption, do you feel it would be more appropriate to use the caloric needs of a larger creature with comparable strength, or some sort of average of this and what the magically-enhanced creature’s mass tells us? Note here we are assuming a rather active Pixie (as active as a human who needs 3000 kcal/day), so that enhanced strength is going to be seeing recular use.

If it's getting the power from oxidizing food molecules, it's going to have waste heat, which has to be gotten rid of. That's going to raise its body temperature, unless you give it expanded surface area. Maybe those wings are there for more than flying.

[AlexanderHowl]

You also need to consider waste products. A 10 lb pixie that consumes as much as a 150 lb human is going to be using the toilet 15x as frequently due to having insufficient capacity for waste products within their body. If we assume that the average human spends fifteen minutes a day using the toilet, a pixie would require proportionally longer times (nearly four hours a day). They will also need to spend proportionately more time eating and drinking, so they would end up needing 36 hours every 24 hours just for toilet, meals, and sleep (meaning that something has to give).