So, strength is a bit unusual in that though he's a kaiju that's clearly inspired by Godzilla, he's completely artificial and was created deliberately to serve as a mobile fortress in The Union's (no, not that one) war effort.
Strength is an intelligent, heavily-pneumatized, bipedal, lizard-like creature with a total length of 15 meters, slightly larger than a T-rex (If said T-rex was upright), and with pretty strong arms to help him throw rocks at people.
He's much smaller than Roland Emerich's or the animation's Godzilla, however, Strength is a weapon, not a mere animal. Other than a reinforced hide, he has strap-on artillery and hard-kill countermeasures against pesky missiles, occasionally armor, military knowledge, and training in a modified version of Brazilian Jiu-jitsu and baseball throwing (if you've seen Attack on Titan, you know why).
In terms of basic energy consumption, i.e: when not hauling equipment around, Strength has periods of "heightened state", where he temporarily becomes endothermic, usually for the duration of a battle, then mellowing down after going back to the water.
However, if Strength was, for the most part, spending time in a military base, what were they feeding him? I mean, logistics in the military is already a nightmare without having to feed a pet T-rex. I'm sure they'd cook up a cheap, easy-to-produce but nutritious thing, but what exactly?
No, Wilk, The Confederacy (whom The Union was fighting against) relied on cheap robots and the occasional Jaeger (A GIANT ROBOT around the same height as Strength). Strength might be an omnivore with a lead stomach, but RHA isn't exactly nutritious, and guillotining a Jaeger for using the name of a much better character takes a lot of energy.