The one metric to optimise. What is a "good" metabolic rate / gram of tissue?

[EnergeticLeo]

In Peat's Optimizing Respiration newsletter, he says:

In a given situation, people who eat more are healthier and live longer than those who eat less-- their bodies burn calories vigorously. In one study, fat people were found to be able to maintain their weight on only 700 calories per day, about a third of a normal calorie intake. In animal studies, too, the fast-metabolizers live longer than the animals that don't burn calories so fast. When animals are fed a calorie-restricted diet, and live longer than their ad lib fed relatives, people like to say that their "metabolic rate is depressed," but that isn't true: the under-fed animals are smaller than the ad lib eaters, but each gram of their tissue bums energy at a higher rate.

Does anyone have any sources of data on what the population average for metabolic rate adjusted per gram of bodyweight, and adjusted for physical activity? It would be interesting to have a benchmark.