An interesting study was done in 2011, where subjects received an intragastric infusion of fatty acid solution or saline during neutral or sad emotion induction and rated sensations of hunger, fullness and mood.
The behavioural and neural responses to sad emotion induction were attenuated by fatty acid infusion.
Is that why we crave certain foods when we feel sad, like ice-cream, potato crisps - and other fatty snacks? Maybe we are changing some gastric peptides that are signalling to the brain differently when we eat these fatty foods.
However, long term, this is not a solution as such eating habits bring with it a host of other health problems, as well as potentially the more long term negative effects in mood associated with poor eating habits.
J Clin Invest. 2011 Aug; 121(8):3094-9. doi: 10.1172/JCI46380. Epub 2011 Jul25.