Comfort eating is triggered by nurture, not nature

The portrayal of a heartbroken woman devouring a tub of ice cream under a duvet is a well-established television cliché – think Bridget Jones. That’s probably because it’s actually quite a common behaviour: 38 per cent of adults say that they eat more when stressed or sad.

You may be all too familiar with the scenario: you’ve had a particularly gruelling day at work, or you’re in the throes of a devastating break up, and you reach for your favourite food for comfort.

Scientists call this tendency “emotional overeating”, reacting to negative emotions such as stress or sadness with the desire to eat highly palatable food.

The problem is that it increases your risk of becoming overweight: regularly eating a large number of additional calories for reasons other than hunger will do your waistline no favours.

We know from previous research that a tendency to eat for comfort begins in early childhood, yet we know very little about where this actually comes from, especially during the important formative years. To find out more, we recently conducted two studies of emotional overeating in children from the UK and Norway. In one study of British twins, we looked to see if this tendency is shaped more by our early environmental experiences, or genetic predisposition. In the other study of Norwegian children, we looked to see if parents play a role by offering food as a source of comfort to their young children.

It is useful to understand how our tendencies are shaped; this knowledge provides guidance about where to focus efforts to stop problem behaviour from developing in the first place. A powerful method for understanding how genes and environments shape our traits is comparing identical and non-identical twin pairs.

Identical twins share 100 per cent of their genes, while non-identical twins share about half of their genes – the same proportion as regular siblings. But both types of twins are raised in the same environment and share similar experiences. For example, they are the same age and raised in the same home. Researchers can therefore compare how similar the two types of twins are to establish the extent to which genes and environments shape emotional overeating (or any other trait of interest).

If identical pairs are more similar to each other in behaviours (such as emotional overeating) than non-identical pairs, this indicates that genes play a role. However, if both types of twins show equivalent similarity, it can be implied that the environmental experiences shared completely by twin pairs, such as upbringing, are more important in influencing behaviours.

To find out about the role of genes and environments in shaping emotional overeating in childhood we analysed data from the Gemini study, a large study of more than 2,400 British families with twins born in 2007. Parents rated their twins’ tendencies to emotionally overeat when they were toddlers (16 months), and again when they were five years old. Results showed that the most important influence on the tendency to comfort eat as a child was the environmental experiences shared by twins. Genes were unimportant.

Early environmental experiences that lead to comfort eating are likely to involve early feeding experiences. Many parents use food to soothe their child’s distress – such as offering a favourite food for comfort when their child has hurt themselves. Researchers call this “emotional feeding”. But using food to soothe may inadvertently teach the child to apply the same tactics themselves when in distress.

A child who is repeatedly fed when he or she is upset or expresses negative emotions learns that eating helps to regulate emotions, and so might learn to comfort eat. To test this theory we studied parents’ emotional feeding and their children’s emotional overeating in nearly 1,000 families from Trondheim, Norway.

Parents rated their tendency to offer their children sweets or snacks to calm them down or cheer them up, as well as their children’s tendency to emotionally overeat. Parents answered these questions several times when their children were six, eight and ten years old.

Our analysis of the results showed that emotional feeding does encourage children to emotional overeating tendencies. Children whose parents often used food to soothe them displayed more emotional overeating as time went on.

The discovery that comfort eating in childhood is learned, not inherited, suggests that it can be prevented. We need to help parents find alternative strategies for comforting their distressed child, such as offering a favourite TV programme or game, rather than a fizzy drink. Of course, the next stage of research would be to find the alternatives that work best.

The authors of this article are Moritz Herle, a PhD candidate at the Department of Behavioural Science and Health, University College London (UCL); Alison Fildes, a university academic fellow at the University of Leeds; Clare Llewelly, a lecturer in behavioural obesity research at UCL, and Silje Steinsbekk, an associate professor at the Norwegian University of Science and Technology. This article first appeared on The Conversation (theconversation.com)