We have three types of memory processes – sensory memory, working memory (which used to be called short-term memory) and long-term memory. Long-term memory refers to anything stored sufficiently well to be accessible more than a few seconds later – not long in the usual sense of the term! But this distinguishes it from sensory and working memory. Long term memories are of events (this is called episodic memory) and knowledge about the world (this is called semantic memory). Here I’m going to focus on episodic memory.
Episodic memory (EM) is the name for our memory of previous episodes or events. How well you stored a record of something that happened depends partly on how much you paid attention when it was happening. What you attend to and what you mentally process at a party influences what you remember of it a week later. How much you can recall of the conversation you had with your friend’s neighbour will depend on how well you were listening, what competing demands there were on your attention, how drunk you were and so on.
Memory and eating
Professor Suzanne Higgs and Dr Maartje Spetter wrote an excellent paper in 2018 on the cognitive control of eating, which reviewed the role of memory in eating behaviours and the associations between memory and weight gain. I’ll summarise some of the key points here, and what they mean for us working with clients, but the original paper is Open Access and well worth reading.
The paper starts with the point that each and every eating decision we make every day is the result of sensory, emotional, socio-cultural and contextual information. When you see the cookies and the fruit bowl next to each other, whether you reach for a cookie or an apple depends on how your working memory computes all these things. As I’ll describe, studies by Professor Higgs and her team have resulted in a very simple tip that you can use with your clients who want to reduce how much they eat.
Episodic memory processes are involved in the control of eating.
Memory processes are fundamental to food-related decision making. The associations between past experiences of eating and their outcomes (sensations and feelings) are stored in memory. How you felt as you ate a samosa or drank a cappuccino is stored as a memory, and if you’ve had lots of experiences of feeling the same with a particular food, the association will be all the stronger. Although of course one bad experience with a food can result in powerful one-trial learning of subsequently avoiding that food.
The work by Suzanne Higgs and her colleagues found that episodic memory doesn’t simply influence our likes and dislikes. They studied what happened in the lab when people were provided with a fixed lunch and then 2-3 hours later asked to recall what they remembered about eating this meal. The results were fascinating. Recalling today’s lunch led to reduced snacking in the afternoon, but snacking wasn’t reduced when people were asked to recall what they ate for lunch yesterday, or a recent exercising episode. They also found that this effect of reduced snacking is larger when recall takes place a few hours after lunch than when it is only an hour after lunch.
They concluded that recall of recent eating inhibits consumption and that episodic memory for recent eating itself plays a part in registering satiety (fullness). Higgs and Spetter suggest that episodic memory may allow us to use information about recent eating together with knowledge about current food availability to adapt motivation to eat accordingly.
Paying attention to what you’re eating strengthens or weakens the effect of memory
- If you disrupt the encoding of the meal memory whilst eating, by watching TV or playing a computer game, you eat more afternoon snacks than if you eat the same amount of food without distraction
- Focusing on food whilst eating is associated with reduced snacking later – not because you’re consciously thinking “I had extra potatoes so I’ll give these biscuits a miss” but by subconscious processes. And anything that helps you eat less without having to put in mental effort is a good thing if you’ve been overeating, because you don’t need so much willpower
What is the link between memory and weight gain?
Higgs and Spetter review research studies which indicate that high Body Mass Index (BMI) is associated with memory impairments in adults. Longitudinal studies suggest that where there is memory impairment, the cognitive impairments may predate the weight gain. It is thought that memory impairments might contribute to over-eating and weight gain and in turn weight gain may lead to memory problems, possibly by inflammation in the brain. A vicious cycle can result of memory impairments leading to overeating and weight gain, which then leads to more memory problems.
The paper ends on an optimistic point that cognitive problems associated with obesity are reversible. A systematic review of the literature by Veronese et al (2017) concluded that weight loss in people with obesity is associated with improvements in cognitive performance. An area of considerable research interest at the moment is using cognitive training programmes to alter eating behaviour by training working memory.
Clinical take-home points for you to use with your clients
What I love about this research is that it gives us a really useful free, quick way of reducing the amount you eat.
If you’re tempted to snack in the afternoon despite not being hungry, deliberately recalling what you ate for lunch earlier today means you’ll snack less
And remember these additional points for your clients:
- When you’re eating, avoid distractions. How much we eat is influenced by how much we focus on it – watching TV while we eat leads to increased intake at this meal
- Although this research was about lunch and afternoon snacking, try it as a suggestion for clients who struggle with snacking in the evening – in this case, suggest that they think about what they ate for dinner when they are tempted to reach for snacks that they don’t really want/need.
- If you would like to learn more about how cutting edge clinical and applied psychology research on eating and appetite can help your work with clients, join me on one of my workshops.
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Higgs, S and Spetter, M.S. (2018) Cognitive Control of Eating: the role of memory in appetite and weight gain. Current Obesity Reports 7 : 50-59
Veronese N. et al (2017) Weight loss is associated with improvements in cognitive function among overweight and obese people: a systematic review and meta-analysis. Neurosci Biobehav Rev. 72 : 87