Rachael Reynolds wrote:

But broadly speaking, we are all the same - at each end there are extremes -
supreme atheletes at one end and at the other there are the people with a
major lack of dopamine receptors or whatever, but the vast vast bulk of us
are averagely in the middle.

There's no such thing as being in the middle genetically. You are
unique. 50% or more of obesity is said to be related to genetics.
Whatever your genetics are what you have to fight. If you keep thinking
you are just a total failure because you think it is all psychological
then you aren't understanding the enemy.

Not sure about this rat thing anyway - they didn't have to think about
whether they want to gain, lose or maintain weight. The psychological thing
is too important to be ignored.

That's not what is ignored. That's all people talk about.