The power of hunger

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Evolution / Health / Myths / Psychology / Zoology

You’re probably aware that going to the supermarket when you’re hungry is a bad idea. Research published back in 1969 showed the hungrier you are, the more food you are likely to put in your trolley as a result of impulse buying. But that’s not the only way hunger affects the choices we make.

It's not a good idea to shop when you're hungry. Image credit Luis Giles via Flickr.

Don’t do your supermarket (or any) shopping on an empty stomach. Image credit Luis Giles via Flickr.

A growling stomach

When was the last time you were too busy to eat lunch and then found yourself suddenly starving at 4 pm? When you finally prioritised the task of getting food, what did you buy?

It may be that rather than buying more food, you simply bought more calories. Research published in 2013 found hungry shoppers tend to buy more junk food. This is probably because going without food means the reward systems in our brains are biased towards high-calorie foods.

Hungry people buy other stuff too

Research published last week showed it’s not only our decisions about food shopping that are affected by hunger. Obviously when we are hungry, we are motivated to find and get food. But it turns out our desire to acquire things spills over to stuff other than food.

If you offer samples of a boring piece of stationary to people who haven’t eaten for four hours, they take 70% more samples than people who have recently eaten. And the pattern goes beyond free samples. Taking into account how long the study participants had been shopping, hungry people spent 64% more money shopping for things other than food than less hungry people.

If you’re really hungry, you’d better think twice before purchasing any items at all or you might regret those purchases later.  Alison Jing Xu, University of Minnesota

Love at first meal

In a type of bug called a water strider, hungry females are much more likely to mate with large rather than small males. Similarly, hungry wolf spider females prefer large males.

Think humans are immune to such effects? Think again.

Men who feel hungry prefer heavier women than those men who feel full. Researchers argue men have evolved to be more attracted to women who presumably have more access to food when they themselves lack access to calories.

Taking risks

It isn’t surprising that the hungrier an animal is, the more risks it is willing to take to find food. This behavior has been seen in everything from fruit flies, to rats and foxes.

What you may not be aware of is that you are also more likely to take risks, even financial ones, when you’re hungry. Researchers observed men making gambling choices after fasting for 14 hours, immediately after eating a meal, and one hour after eating a meal. The men were much more likely to make a risky choice when they were hungry than when they were full.


The very fact that the word ‘hangry’ exists points to the fact that being hungry can affect our mood. An extraordinary example of this came from researchers following eight judges as they ruled on more than 1000 applications for parole over 10 months. The judges had two meal breaks a day, meaning that each day was effectively broken into three parts.

At the start of the day, the judges approved about 65% of applications. As time passed, this percentage dropped rapidly, and reached zero. But remarkably, after each of the meal breaks, the approval rate was back at nearly 65% before falling again.

Moral of the story: don’t shop when hungry, be aware of the risks you are taking and if you ever need a judge to find in your favour, provide a tasty snack first.

Links and stuff

Check out the graph in this Economist article about judges’ decisions being influenced by meal breaks

Did you know just imagining eating a food makes you want to eat less of it?

Research published last week: why using marijuana gives people the munchies

Radio on demand

 This post accompanies a radio segment on Triple R’s Breakfasters program on Wednesday 25 February 2015. 



  1. Wow, this is amazing research. As a risk manager I found the risk taking example really interesting. Humans are a fascinating species, they think they are so smart and in control of their destination and yet here are some wonderful examples of behaviour going by without even being noticed.

    Mental note to self, next Christmas shop after big brunch 🙂

    • I agree. It’s extraordinary that we think of hunger as so benign yet it can clearly have a massive influence on us. Seems a good reason to try and avoid ever getting too hungry 🙂

  2. I can totally relate to this. I prefer to go shopping when I am not hungry, that way, I don’t spend as much and I stay focus.

  3. Pingback: Smells like nostalgia | Espresso Science

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