Hi,

I've been successfully using "The Hacker's Diet" (calorie counting
with some engineer-friendly software tools) as an inspiration
to getting back to a (for me) acceptable weight, losing about 25 kg
over the last 10 months.

I've assumed that a kaloric intake deficit of 7700 kcal results in
the loss of about 1 kg of body fat and have calculated my BMR and
target intake accordingly.

However, lately I've wondered : how accurate is that ?
Assuming that 7700 kcal of food can be metabolised by the body to
a certain amount of usable energy (exactly those 32.24 MJ), then
metabolizing this energy ino fat can't be 100 % efficient. On the
other hand, metabolizing 1 kg of fat into usable energy can't be
100 % efficient either, so the assumptions
 'eating 7700 kcal above needed energy over a period of time
  results in a weight gain of 1 kg'
and
 'eating 7700 kcal below needed energy over a period of time
  results in a weight loss of 1 kg'
can't be accurate - even if they worked very nicely for me.

Can someone point me to an online document clarifying this ?

Thanks in advance,

Chris

1.86 m
113 kg -> 87.6 kg