The TV chef told Red Magazine that her menu method was similar to Constantin Stanislavski's acting system.
Stanislavski's system, first developed in the 1910s and developed further in the 1930s, uses emotional memory and physical actions to help actors make their performances believable.
"I have a Stanislavski method of ordering," Lawson explained. "When I read a menu, I put myself in the position of eating all these things, and whichever one feels right, I order."
She added: "Most women haven't cracked this. They're torn between what they should eat and what they want to eat.
"So I think, 'What do I want?' I was thinking of having the eggs. And then I thought, 'No, I want a full English'."
Lawson said: "I can't be a diet person - it drains the pleasure out of life. So I just stopped having second helpings. I'd rather eat a bit of everything than a lot of something.
"I had to find a way to take guilt and self-loathing out of the equation. It's hard but it makes such a difference.
"So if I go out and have bread and wine and a big bowl of pasta, I think, 'That was really delicious'. I don't think, 'Oh God, I'm really fat, I shouldn't have eaten all that'."
The full feature appears in the January issue of Red Magazine, on sale now.