EDIT: According to Wikipedia [0], the Imperial unit of energy is ft⋅lbf.
The kcal (kilocalorie) is what most people mean when they refer to calories in food, and that's just the energy needed to heat 1 kg of water by 1 deg C.
Since a person is mostly water this means that, say if you weigh 100 kg, and eat 1000 kcal of food, that food contains (theoretically) enough energy to heat your body mass by 10 deg C. The units do give a kind of intuitive understanding of the energy in food, while also being based on metric quantities.
It's sold in MWh in the rest of Europe.
No need for perhaps, unless it's btu (or some horse power/hour) it's metric.
Watts are a metric unit, as are seconds. Hours are not formally an SI unit, but at least according to Wikipedia [0] are "officially accepted for use with the SI".
[0] https://en.m.wikipedia.org/wiki/Non-SI_units_mentioned_in_th...
It doesn't mention one product that is very much in the news at the moment: energy. I'm fairly sure they still sell it by the kWh rather than the MJ.
Colloquially, people still talk about calories rather than kJ in food. (And they do that even in Germany, I think, one of the few places where they measure font sizes in mm rather than points, or so I've heard.)
EDIT: Perhaps kWh counts as metric, even though it's not SI?