Seems to me a 250lb, 6'7' Man would have higher energy requirements than a 80 lb lady. Why are they the same?

I would think that our body would be able to adapt to different requirements. More work, take in more food. Bigger body requires more sugar, glucose etc to meet requirements. How come I cant find normal blood sugars for a 6' tall 220 lb man. I cant believe mine should be the same as a 80 lb lady that knits.