"you can move parts of your body because of energy from the sun" describe a series of energy conversions that supports this idea

-- Hydrogen in the sun's core converts to Helium.  A little bit of the mass
converts to tons and tons of nuclear energy.  It floats out to the surface
of the sun during the next few million years, and leaves the sun in the
form of electromagnetic energy, which includes heat and light and
also other stuff.

-- A little bit of that energy radiates in the direction of the Earth.

-- About 8 minutes after it leaves the sun, a little bit of THAT little bit
actually hits the Earth.

-- A little bit of THAT little bit is absorbed by plants.  It gets
converted to chemical energy and stored in the plants.

-- A cow or a steer eats some of the plants.  Some of the chemical
energy stored in the plants is converted to the kind of chemical energy
that can be stored in a cow or a steer.

-- I have a glass of milk for breakfast and a thick juicy steak for lunch.
From the milk, I get some of the chemical energy that was stored in
the cow.  From the steak, I could get some of the chemical energy
that was stored in the cow OR the steer. I'm a little hazy on the details.

-- I have a nice big salad for dinner.  From the salad, I get some of the
chemical energy stored in the plants.

-- I convert the chemical energy from the cow, the steer, and the plants
into the kind of chemical energy that can be stored in human fat.
My body has so many fat places that I have no trouble finding somewhere
to keep all the chemical energy that comes my way, no matter how much.

-- During any normal day, my body takes some fat out of those places,
converts it into glucose (blood-sugar), and dumps the glucose into my
blood.

-- I try to avoid it, but whenever I absolutely MUST move some part of
my body, my muscles grab some of the glucose from the blood running
through them. 

-- The muscles convert the glucose into mechanical energy, which I use
to walk around, think, complain, type on my computer, sing, and breathe.