Attention and memory are independent of each other, but they are closely linked – we cannot remember something that we did not pay attention to and, by the same token, our memories of something tend to be more vivid the more we attend to it.

It’s therefore possible that a vivid memory of lunch could reactivate the body’s physiological state, so that we do not feel so hungry, and consequently eat less at dinner. On the other hand, someone who was distracted during lunch would form weak memories of the meal, and so thinking about it at dinner might make them feel hungrier and eat more.

In one 2011 study, for instance, half the participants played Solitaire on a computer while eating their lunch. Sure enough, they had hazier memories of their lunch and went on to eat significantly more biscuits later on than those who did not.

This is particularly interesting, given the evidence that over-eating can impair your memory, with both the over-eating and the memory problems reinforcing each other, pushing you down a slippery slope. “Our research suggests that you might eat more if you have an impaired memory,” says Robinson, “so you end up in a vicious cycle where memory’s impaired by an unhealthy lifestyle, and then that impairment promotes over-consumption.”

He points out that we still have to be careful not to draw firm conclusions, though, until we have stronger proof that this vicious cycle exists and has a real effect on people’s health. “This idea makes sense intuitively, but there’s still no direct evidence for it.”

Staging an intervention

In the meantime, the finding that food memories and awareness can influence eating behaviour does at least suggest a novel approach to helping people lose weight and maintain a healthy BMI, and Robinson and his colleagues have developed a smartphone app that encourages people to eat more attentively.

“There’s now convincing evidence that attention and memory affect how much people eat, but this comes from laboratory studies,” says Robinson.“We’re trying to see if the lab findings translate to the real world. Our app encourages people to take photos of what they’re eating and answer questions about their meals, the idea being that creating vivid memories will make them less likely to overeat during the day.”

Cheke and her colleagues are now following up their initial findings by trying to pick apart the various factors that contribute to obesity, in order to try to determine which are likely to influence brain structure and function.

They are also using a smartphone app to collect information about people’s lifestyles and behaviour, and are recruiting volunteers in and around Cambridge to help them gather the data they need.

“One person may be obese because they don’t do any exercise and eat a lot of junk food,” says Cheke. “Another might be obese for genetic reasons but actually eat really well and do lots of exercise, and yet another may be obese because they have insulin problems.”

“We’re trying to get all these different variables to see the relative contribution, so we’ve got people out wearing activity monitors and filling food diaries for us. Doing studies like this is the only way we’ll be able to tease these things apart.”

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Moheb Costandi is the author of Neuroplasticity (MIT Press). He tweets as @mocost.

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