In response the suggestion from E-S, at top of comments to the last post, that caloric output should be measured using a calorimeter:
Direct calorimetry identifies deficiencies in respirometry for the determination of resting metabolic rate in C57Bl/6 and FVB mice
"In a carefully controlled study, Walsberg and Hoffman (10) examined the accuracy of respirometry in multiple species, including the kangaroo rat (Dipodomys merriama Mearns), dove (Columbina inca Lesson), and quail (Coturnix communis Linnaeus), by comparing simultaneous outputs from animals studied with both direct and respirometry methods. Those authors concluded that when disparate species were studied under various conditions that estimations of heat production by RER-based respirometry calculations led to errors averaging 21% for kangaroo rats, 15% for doves, and 17% for quail".
"Here, we demonstrate that the rate of inaccuracy of respirometry [for the CL57Bl/6 mouse] is roughly 10–12% and posit that this magnitude of inaccuracy, given the target range, is unacceptably large. We conclude that the challenges faced by the obesity therapeutics research community in identifying or validating novel therapeutic targets in mice (and likely other species as well) may be compounded by the inappropriate yet almost universal and sole reliance upon respirometry".
RER underestimates calorie output, compared to a calorimeter. But you can't buy a calorimeter off the shelf.
So folks use RER and that table. "Everyone does it". Yeah. Well.