I don't know how you did that math, but you cannot convert kcal to mAh, you need a unit of energy like watt hour 2000 kcal * 4184 (J/kcal) / 3600 (seconds) ~=

I don't know how you did that math, but you cannot convert kcal to mAh, you need a unit of energy like watt hour 2000 kcal * 4184 (J/kcal) / 3600 (seconds) ~= 2324 Wh which is... a lot of batteries (a large laptop battery is around 100 Wh) A human at rest uses around 100W, which is easier to remember.