Above: Image © LPETTET, iStockphoto

So there I was, on the couch, watching The Simpsons. A beautiful, bright, pink glazed donut with multicolored sprinkles appeared on the screen. I couldn’t help but say it out loud with Homer: “Mmmmmm… Donut.” Been there? Done that?

You may already know that a diet too high in fat and sugar can lead to diseases like obesity. But if junk food is so bad for you, why does it taste so good? It’s partly because humans have evolved to crave foods high in sugar, salt and fat—three nutrients your body requires. But it’s also because junk food is engineered to exploit these cravings.

Did you know? Human taste buds detect five different tastes: sweet, salty, sour, bitter and umami (also called savoury).

The evolution of food cravings

In movies and cartoons, fictional cavemen like The Croods are often obsessed with food. But real cavemen probably worried about food a lot too. In prehistoric times, famine and malnutrition were major causes of death. Finding food rich in fat, salt and sugar was hard work!

When you eat these foods, your taste buds send signals to the pleasure centre in your brain. This response likely evolved in your cavemen ancestors. It ensured they craved and ate lots of foods high in the nutrients they needed to survive.

Human bodies also evolved a way to store food reserves as fat. In prehistoric times, people who who could store more fat while eating less food had the best chances of surviving and having children. These children, in turn, inherited this fat-storing advantage through their genes.

Cavemen would have also found cavewomen with more fat more desirable. They women looked healthier, and had an easier time bearing children. So you can see how finding nutrient-rich food could help both individuals and the species survive!

Did you know? Different nutrients activate different taste receptors. These receptors help you decide if a food contains something your body needs, or if it will harm you.

Making junk food irresistible

There’s another big reason why you might find junk food addictive. Food products are actually designed to take advantage of the human body’s desire for all things sweet, salty and fattening.

The ideal ratio of sugar, salt and fat is called the bliss point. When you eat a product designed according to the bliss point, the neurotransmitter dopamine gets released in the pleasure center of your brain. As a result, you associate eating that product with pleasure. This causes you to crave it—and, of course, to buy more of it!

Much of the food you can find in a grocery store is processed. That means it’s altered in some way from its natural form. Manufacturers strive to add sugar, salt and fat to food products in just the right amounts so that two or three of these nutrients are at the bliss point.

To test a product, manufacturers create several versions of the same snack or drink. Each one has a slightly different ratio of sugar, salt and fat. Ordinary people taste the different version and rate how much they enjoyed each one. They also state which one they preferred.

A food product’s popularity depends on several factors. These include mouth feel (taste and texture) and maximum bite force (how hard you have to bite to break up the food).

Another factor, sensory-specific satiety, evolved from your cavemen ancestors. It refers to how quickly you lose interest in a snack or drink as you’re consuming it. Think of various snacks you’ve tried. Those with interesting flavours or textures probably keep you munching for longer. Or think of the times you have felt full after dinner... but then suddenly had room for dessert! That’s sensory-specific satiety at work. But it started out as encouragement for your cavemen ancestors to eat a variety of foods, and therefore get the nutrients their bodies needed.

Did you know? To determine the bliss point of regular and diet Dr. Pepper, the manufacturer created 61 different formulas. They were tested at almost 4000 tasting events held across the United States.

But I’m not a caveman!

Unlike your cavemen ancestors, you have plenty of options to get your fix of sugar, salt and fat. You also spend a lot less energy than they did getting these nutrients. At worst, you might have to walk to the store! Because of this constant access to foods high in these nutrients, many people have become overweight or obese.

Let's talk about it!

  • Have you ever eaten anything where the bliss point might have been at work? What was it?
  • Have you ever experienced sensory-specific satiety? When?
  • Given the increase in obesity, do you think it is wrong of the food industry to take advantage of the bliss point? Could or should its use be banned?
  • What are some other strategies for keeping people from eating too much sugar, salt and fat?

Learn more!

About obesity:

A history of obesity, or how what was good became ugly and then bad (2006)
G. Eknoyan, Advances in Chronic Kidney Disease 13

Global Health Observatory data: Obesity
World Health Organization

About taste, cravings and the bliss point:

What is Bliss Point? (Besides the Reason You’re Addicted to Doritos) (2014)
J. Andrews, The Blot Magazine

Eating processed foods (2014)
National Health Service

A Taste for Satiety (2014)
D. L. Katz, U.S. News.

Food cravings engineered by industry (2013)
K. Crowe, CBC news

What is a processed food? You might be surprised! (2010)
International Food Information Council Foundation

Taste receptor genes (2007)
A. A. Bachmanov & G. K. Beauchamp, Annual Review of Nutrition 27

About Food Science and Technology
Institute of Food Technologists

Marie-Lyne Fillion

 






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