That happens to me. I'm not a doctor, but i'm pretty sure that feeling hungry is a psychological thing. The emotions take over when i'm stressed, so I don't think about what's in my tummy! It always helps to have some really nice food placed in front of me (cooked by someone else!!)
Is it something to do with adrenaline? When you are stressed your body takes over- giving you adrenaline to cope with the shock. This overwhelms any previous sensations you had, such as food. I think this may be why we lose our appetite. Regarding eating more, that could be comfort eating.
You're probably somewhere on the right lines there Scarlett .Still there is one up side to it i suppose, all those pairs of jeans that have been pushed to the back of the wardrobe over the last six years now fit me perfectly.