Measuring your food waste for six weeks can change your habits – new study

You’ve had a long day and you’re tired. Faced with making dinner, you look in the fridge and decide to cook something that requires little effort. This is a common scenario, and one that many people act out without really thinking about it.

The fact that there is often little or no conscious thought involved in routine daily food preparation means that ingredients that must be used before they expire are often left to go off.

In research that colleagues and I recently published, we found that overcoming this habitual behaviour is key to cutting food waste. Here’s how to do it.

Every year, 1.3 billion tonnes of food is wasted globally. This is the equivalent of one-third of all the food produced for human consumption.

In the UK alone, households wasted 6.4 million tonnes of food between 2021 and 2022. Accounting for the fossil energy used to grow and harvest that food, as well as the greenhouse gases released when it rots in fields or landfills, this waste equates to 18 million tonnes of CO₂ emissions.

Food waste harms the environment, but reducing how much food is produced only to be thrown away can curb hunger. It could also save the world more than US$120 billion yearly (£96 billion) – and around £700 a year per household.

We measured fruit and vegetable waste from 154 households across the UK for an initial six-week period. Fruit and vegetables are among the most commonly wasted types of food. This may be because supermarkets often sell these ingredients in bulk or because people buying them sometimes fancy something less healthy and more convenient to prepare when the time comes to cook.

During those six weeks, half of the participants were asked to log what fresh fruit and vegetables they bought and when their purchases had to be used according to the label on the packaging, as well as guidelines provided by the researchers.

In each of these homes, the log was placed on the fridge as a daily reminder of what needed to be used each day to avoid waste. Participants also received daily text messages reminding them to check their food log and add any newly bought fruit and vegetables.

The other half of the households involved in this experiment simply measured their food waste at the end of each week without any reminders to use the fresh produce they had.

We expected the half of households receiving reminders to cut their waste more effectively – in fact, there was only a small difference between the two groups. But we did find that simply measuring fresh produce waste made all households more likely to think about what they were wasting.

This was evident from a range of responses from the participants. Taking part in the study also made participants feel as if they could control the amount of food they were throwing away.

It seems that simply asking people to measure their food waste each week for six weeks kickstarts a thinking process that guides people’s behaviour in future.

Food waste on the brain

Our findings may seem obvious, but there is more to them.

We found that across all households the reduction of fresh produce waste averaged 108 grams a week. This was sustained for six months after the experiment ended.

The experience of measuring food waste weekly during the experiment seemed to instil a mindfulness about food waste that meant participants were still throwing less away half a year on. It is interesting that only a short period of conscious effort is necessary to encourage lasting changes in behaviour.

Research into the psychology of food waste tends to focus on nudges, which are subliminal actions to change behaviour, such as menus designed to highlight plant-based options. It is not clear whether such methods, which bypass the conscious mind, work in the long term.

Our study suggests that it takes thought to alter habits. But the good news is that we found people only had to think about reducing food waste for a short time to form an enduring habit of reducing the amount of food they throw away.

Most people have busy lives and simply don’t have the mental capacity to spare each day. Strategies for reducing food waste that require only a short-term commitment of mental effort are likely to be most effective.

And even a small reduction in household food waste can make a difference. Our study showed that it is relatively easy for people to cut how much fruit and vegetables they discard each week. If just 1,000 people could do the same, it would save over 9.5 tonne of CO₂ a year, the equivalent of 1,140,000 smartphone charges.

Thinking about food waste for six weeks is a small price to pay if the result is a significant and long-term difference to our planet’s wellbeing.

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Cathrine Jansson-Boyd received funding from the Waste and Resources Action Programme (WRAP).