If you increase the amount of energy flowing into the human body, the metabolism increases as well (although almost never proportionally - there are many variables) to compensate.
Similarly, it's rather unlikely that humans will continue to use exponentially increasing amounts of energy, unless we intentionally do something to effect that. Human population growth, which is partially driving energy consumption, is not exponential (it would be exponential absent of resource constraints or cultural factors, but guess what - both of those are in effect rather strongly in the real world) - and neither is energy consumption per capita. For instance, from 2005 to 2020, the US gained 30M people[1] while keeping energy consumption roughly constant[2].
[1] https://datacommons.org/place/country/USA [2] https://www.statista.com/statistics/201794/us-electricity-co...
