You invent a new drug that alters a person’s biochemistry such that treated people will extract 100% of the energy from the oxidation of glucose to be converted into ATP, instead of only 41% as usual. People living near the equator do okay with the drug but people living near the poles of our planet consistently die from the drug. What did you not consider (what did you do wrong)?
You forgot that the glycolysis step of cellular respiration generates 36 ATP per glucose burned, thus people taking your drug and living in cold environments would not be able to oxidatively phosphorylate the needed ammonia for our biochemical functions.
Your drug is obviously just ATP and you forgot that ATP is toxic to humans. People living near the poles die because ATP is more toxic at lower temperatures.
None of these explanations could be correct.
Actually, all of these explanations could be correct, except of course for the none of these answer.
You forgot that we are endotherms who get heat from the thermal energy given off due to cellular respiration, thus people taking your drug and living in cold environments would not be able to generate the heat needed for our biochemical functions.