Question

why is it more efficient to store energy as lipid rather that as glycogen?

Answer 1

There are mainly 2 reasons

1) we know that

the energy yield per gram of lipid is 38 kJ/g

and

energy yield per gram of glycogen is 17 kJ/g

we can see that

energy in case of lipid is twice the energy in case of glycogen

2)

we know that

lipid is stored as anhydrous lipid droplets

but

glycogen is stored in hydrated form

and

because of this hydration , the effective weight of glycogen is tripled

so

This increase in effective weight reduces the energy yield to about 6 kJ/g

So

it is more efficient to store energy as lipid rather that as glycogen