Well from what I understand, food constumption is directly related to body chemestry.
For many people, a happy relationship released massive amounts of dopamine and seratonin into the brain producing a feeling of well being and 'rose colored glasses'. Depending on what people psychologically associate food with (well being or lack their of) they will eat more or less as the relationship chemicals flux.
Me personally, the happier I am, the healthier I am. When I'm depressed I tend to eat a lot but loose weight constantly due to 'raging metabolism syndrom' that is triggered by trying to replace seratonin with carbs. 0_0
With all my heart I will love and not fail,
With all my soul I will fly and not fall.