The effects of mood on eating behaviour.
Hunger is associated with increased arousal, vigilance and irritability, while after a meal we feel calm and sleepy and general pleasurable feelings.
Studies have shown that people who are stressed and depressed increase carbohydrate and fat content of their meals (Gibson). Eating these sorts of food gives people a better mood and more energy. We also know that most people find sweet tastes pleasurable.
THE SEROTONIN HYPOTHESIS: Carbohydrates such as chocolate contain tryptophan. This is used by the brain to produce serotonin; low levels of serotonin are associated with depression. People with stress/depression take in more carbohydrates because it leads to an increase in serotonin and an increase in mood.
THE OPIATE HYPOTHESIS: In the brain we also have opiate neurotransmitters; they are released from neurons and act at synapses with opiate receptors. Opiates are chemically very similar to the opiate drug, heroin and heroin acts on these pathways. Heroin produces a very pleasurable feeling; therefore it seems likely that the opiate pathways are part of the reward pathway in the brain that control out feelings of pleasure.
When we eat sweet foods/carbohydrates, the reward pathwways in the brain are activated by the release of endorphins; so we feel better after eating such foods because they activate our natural pathways.
Garg et al observed food choices (popcorn or grapes) of pts as they watched either an upbead, funny film or a sad one. Throughout the films, pts were offered hot buttered, salty popcorn or seedless grapes. Garg found that pts who watched the depressing 'love story' consumed 36% more popcorn than those who watched the upbeat film, 'Sweet Home Alabama'.
Garg et al suspects that this is because happy people want to maintain or extend their oods in the short term, but consider the long term and so turn to the healthy food with more nutritional value. People feeling sad just want to 'jolt themselves out of the dumps' with a quick indulgent snack that tastes good and gives them an immediate 'burst of euphoria'.
However, when pts were presented with nutritional information prior to viewing, consumption of the unhealthy food dropped dramatically.
- External factors - personal preference influences choice.
- Lab setting - lacks ecological validity and mundane realism - not real emotions.
- We can establish cause and effect in a lab.
White showed 4 different films to overweight and normal weight pts. 3 of the films aroused emotions - an upsetting one, a funny one and a sexually arousing one. The 4th film was a boring travelogue and acted as a control. After each viewing of the films, pts were asked to taste and evaluate different kinds of crackers. He found that overweight pts ate significantly more crackers after…