The science behind comfort eating

We’ve all been there, even if we’d prefer not to admit it. Those evenings spent alone, sporting the least alluring outfit known to man, with one hand clutching a tub of ice-cream and the other wielding an unnecessarily gigantic spoon. We only planned to eat a few spoonfuls but, somehow, before we know it, the spoon is scraping around at the bottom of the tub and there is nothing but a few guilty trickles of melted ice-cream left.

This familiar phenomenon is known as comfort eating, and it will have afflicted us all at some point or other, whether it be during a stressful exam period, in the midst of a difficult breakup or just because we really cannot take another day of eating a lean protein and veg diet and pretending, through over-zealous smiles, that we love it.

I don’t mind admitting that I have, on more than one occasion, caved, and begun merrily slinging eggs, flour, butter and sugar into a cake mixing bowl, just to sit and eat the contents (with that infamous unnecessarily gigantic spoon), with absolutely zero intention of going anywhere near an oven and actually turning this beautiful but filthily guilt-ridden concoction into a cake.

But now, rather than having to feel that next day guilt as we wake up next to the smug face of Ben and Jerry (container, not people, of course), and are reminded of our less than honourable indulgences the night before, science has seemingly come to the rescue, and offered us a number of explanations for our temporary slip up. It seems that a lag in our evolution, juxtaposed with the fast rate of improving technology over the past centuries, may be the culprit.

Ever the social being, our human drive to affiliate with others used to hold a serious survival function. In days when we couldn’t check the freezer for a ready meal or pop to Tesco for a bit of lunch, food was scarce and hard to come by: we had to source it and kill it ourselves; no easy feat, meaning that we never knew when our next meal would come.

To increase our chances of getting food and, therefore, aiding our survival, it made sense to affiliate and form alliances: it was a way to group and share resources, and a way to ensure that others were also on the look out for things which may be of threat to us. To break from the ‘pack’ and lose our social group could be disastrous in our struggle for food, so a mechanism developed whereby we were driven to find and store more resources at times of loneliness, in efforts to avoid starvation.

Sadly, technology moves at a greater pace than evolution, so we continue to be hard-wired with mechanisms in place in the event of calorie scarcity but remain in a world of calorie abundance. There is experimental evidence that people do eat more when they are feeling ‘down’. A study conducted by Meyer and Waller (1999) used subliminal priming with either neutral, appetitive or emotionally valenced word stimuli to induce certain emotional states in participants. Participants were told that their task was to identify which words they had been primed with (a task at which none succeeded) and then, afterwards, were given the opportunity to eat foods provided by the experimenters, as a ‘reward’ for taking part.
This was, however, the main part of the experiment, as food intake was measured. It was found that those who had been primed with emotional words, notably those with words associated with loneliness, ate the most, above the neutral group and the appetitive group, demonstrating that priming people with strong emotions, particularly those encompassing abandonment caused people to eat the most.

I suppose it’s good to know that evolution has got our backs (or stomachs, as it were) and that, during times of sadness, loneliness and duress, our bodies are working to make things better… The only problem with this is that, in evolutionary terms, our body’s idea of what constitutes ‘better’, ultimately means ‘fat’. Fantastic news.

Stress is another factor with a lot to answer for in the realms of eating behaviour. Yet again, there are evolutionary mechanisms set in place to help us deal with this, the most well known being the fight or flight response. This used to be invaluable in the times when we had to be constantly on our guard against predators: we would react quickly to threat with a priming of the sympathetic nervous system, and a sudden release of hormones such as adrenaline and noradrenaline.

As well as contributing to shortened life expectancy and lowering our immune systems, stress has been found partly culpable in periods of comfort eating. Research shows that elevated stress levels also increase levels of the hunger hormone, ghrelin, prolonging our appetite. A study carried out at the University of Texas discovered that mice with high ghrelin levels would eat more when constantly exposed to food than mice whose ghrelin remained at a normal level. In short, increased stress equals increased ghrelin, which equals increased appetite.

But why is it that we are more tempted by fattening foods during times of stress and grief? Comfort eating also seems to function at the molecular level too, with research indicating that food really can lift our mood.

Twelve, healthy weight volunteers at University of Leuven, Belgium, were exposed to either sad or neutral images and music, before half were injected with fatty acids via a drip direct to their stomachs, whilst the other half were given a saline solution placebo. Neither group were aware of which they were given, so sensory effects were bypassed. Sad music and images caused mood to fall, but levels of sadness for those with fatty acids were around 50 per cent lower; suggesting that fat seems to decrease our vulnerability to sad emotions.

So, before you beat yourself up too much the next time you give into a fattening take-away meal, or eat an entire lemon cake from Spar (or maybe that’s just me…?) remember that it is not just willpower you are battling, but also a whole host of other evolutionary mechanisms beyond your control that may be to blame for this lapse.