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Speaker 1: Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,

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Speaker 1: Lauren Vogel bond here. If you're anything like me and

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Speaker 1: you were to keep track of some of your thoughts

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Speaker 1: during a given day, Gosh, I'm hungry would appear on

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Speaker 1: the list a few times, along with perhaps why am

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Speaker 1: I keeping track of my thoughts? But why do we

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Speaker 1: often feel hungry? Let's be clear, we're not talking about

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Speaker 1: actual starvation or hunger as a pervasive global and social issue,

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Speaker 1: which it is and is a whole other episode or seven.

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Speaker 1: We're talking about hunger in typically healthy people with comfortable

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Speaker 1: access to food, the hunger that arises from the physiological

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Speaker 1: need for nutrients to survive. Hormones and the nervous system

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Speaker 1: regulate hunger and eating habits. But how the heck do

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Speaker 1: we recognize when we want to eat, even when we

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Speaker 1: actually don't need food. We spoke via email with Richard Stevenson,

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Speaker 1: a professor of psychology at Macquarie University in Sydney, Australia,

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Speaker 1: where he studies human eating behavior. He says that hunger

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Speaker 1: is by no means a universally identifiable sensation. He wrote,

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Speaker 1: unlike fullness, which there is no mistaking hunger is very varied.

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Speaker 1: It is not a consistent sensation across people, and it

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Speaker 1: has been claimed that feeling stressed can be confused with it.

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Speaker 1: Even some of the biological functions that people associate with

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Speaker 1: hunger a growling stomach, for instance, aren't entirely full proof cues.

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Speaker 1: Stephenson said many people do not report stomach sensations when

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Speaker 1: asked to describe what being hungry is like. Indeed, reports

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Speaker 1: show that people cite headaches, weakness, mouthwatering, and other non

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Speaker 1: stomach related sensations as signs of hunger. Stephenson has also

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Speaker 1: done research that indicates feelings of hunger and fullness are

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Speaker 1: influenced by a myriad of factors, including genetic and psychological

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Speaker 1: differences like depression, anxiety, and eating disorders. Then there's a

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Speaker 1: really big fact our environment can easily convince us into

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Speaker 1: thinking it's time to eat, whether we're hungry or not.

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Speaker 1: Stevenson said that seeing, smelling, or even thinking about food

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Speaker 1: will trick us into believing that our stomach is crying

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Speaker 1: out for nutrients. He pointed out that this is why

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Speaker 1: advertisements for food products work so well, and that affects

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Speaker 1: not just appetite, but how much food we actually consume.

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Speaker 1: A two thousand nine studies showed that both children and

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Speaker 1: adults eat more snacks after exposure to food advertising, and

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Speaker 1: a review found that food adds significantly increase unhealthy food

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Speaker 1: intake in children. In fact, researchers coined the term hedonic

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Speaker 1: hunger to describe the drive for food consumption unrelated to

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Speaker 1: the need for calories. This phenomenon might also give us

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Speaker 1: a clue to another mystery of hunger. How can we

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Speaker 1: claim ourselves ravenous only to find after time passes or

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Speaker 1: a distraction interrupts whatever triggered the hunger, paying that hunger

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Speaker 1: has passed us by. Stevenson says this waning hunger could

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Speaker 1: be related to the idea that our appetite isn't always

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Speaker 1: activated by an actual need for calories, and that quote

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Speaker 1: time is a potent queue to eat. If you usually

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Speaker 1: eat at midday and you miss this, you will feel

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Speaker 1: hungry if you notice the time. So what's the trick

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Speaker 1: to deciding whether you're truly hungry? Is there a scientific

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Speaker 1: method for being able to push away that bowl of

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Speaker 1: chips that you don't need? Stevenson said, in a word, no,

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Speaker 1: most of our biological machinery is geared to make us

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Speaker 1: eat when we see food or things that remind us

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Speaker 1: of food, which was terrific for our ancient ancestors when

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Speaker 1: humans had to spend a lot of time searching for

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Speaker 1: energy sources, but it might leave us at a disadvantage

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Speaker 1: when surrounded by a huge spread of snacks right after

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Speaker 1: a filling meal. Today's episode was written by Kate Kirshner

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Speaker 1: and produced by Tyler Clang. For more on this and

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Speaker 1: lots of other filling topics, visit our home planet, how

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Speaker 1: stuff Works dot com. M