I have heard that your 'attitude' to food influences whether you gain weight or not irrespective of calorie intake.
For example a depressed couch potato who 'expects' to gain weight will indeed get fat. On the other hand a busy, upbeat, person who eats the same amount as the couch potato but does not 'fear' weight gain won't get fat? (Without taking activity into it).
We gain weight because we expect to. We panic if we don't eat and it's this that broadly causes us to starve and so on. It sounds so far fetched but apparently it ties into quantum physics on some level etc?
Perhaps someone learned can explain? I was shocked when a respected, intelligent colleague came out with this the other day!