Liquid Calories

Liquid Calories Photo Credit: Clipart.com

Despite the popularity of dozens of diets, the obesity epidemic continues to spread. A recent study looked to see where all our excess calories are coming from.


A deluge of drinkable calories. I’m Bob Hirshon and this is Science Update.

Americans now take in more calories from soft drinks than from any other category of food. That’s according to Odilia Bermudez and her colleagues at Tufts University’s Human Nutrition Research Center. Using data from 1,000 Americans, they found that about 10 percent of our energy, on average, comes from sugary drinks.


This is high. To put that in context, when I look into other food groups like white bread, for example, six percent of the energy is being provided by white bread.

And bread was our top source of calories as recently as ten years ago.

The researchers also found that people who drink soft drinks were more likely to be overweight. Bermudez says that escalating portion sizes may be a big part of the problem. I’m Bob Hirshon for AAAS, the Science Society.

Making Sense of the Research

Fifty years ago, the average size of a bottle of soda was 6 to 8 ounces. If you saw one of these old-fashioned bottles today, you would think it was made for a doll. A “small” soda nowadays ranges from 12 ounces (in a can) to 16 or more ounces (in a bottle) to 20 or more ounces (in a movie theater). And just about any convenience store will sell you a 64-ounce cup of soda! Overall, according to a 2002 study in the American Journal of Public Health, the average soda portion today is twice the recommended portion size by the FDA.

So it’s no wonder that we’re consuming so many calories from soft drinks. According to the Center for Science in the Public Interest, a consumer watchdog group, the soft drink industry now makes enough soda pop to give every man, woman, and child in America over 50 gallons of soda a year. That’s nearly 11 million calories’ worth of soda per person!

Unfortunately, while portion sizes for soft drinks have gone up, our ability to metabolize them has not. In fact, we’re getting far less exercise than our grandparents’ generation got on a daily basis. What’s more, some studies have suggested that liquid calories are harder to regulate than solid food—in other words, we can take in a lot more calories from soda without feeling full than we could from say, steak or broccoli.

This study doesn’t prove that soft drinks are to blame for the obesity epidemic. It shows us only that the percentage of calories we take in from sugary drinks has increased compared to other foods. But put together with our expanding waistlines and increasing consumption of sugary drinks, it suggests that we may have good reason to keep liquid calories to a minimum.

Another reason for concern is that most sugary drinks have little or no nutritional value. So even if an individual eats a healthy total number of calories, there’s no advantage to getting 10 percent of them from sweet drinks. Even fruit juice isn’t so great, since it’s high in sugar and calories but lacks the fiber that whole fruit has to offer. In short, this study adds another detail to the troubling picture of Americans’ eating habits.

Now try and answer these questions:

  1. What is demonstrated by this study? What is only implied by this study? What’s the difference?
  2. Why should we be concerned about our increasing dependence on liquid calories?
  3. Soft drink consumption in America has actually decreased since 1998. If the percentage of calories we take in from sugary drinks went down in the next five years, would that mean that Americans are eating healthier? Why or why not?

Going Further

For Educators

In the New York Times Learning Network lesson You Are What You Eat, students evaluate their eating habits, focusing on the ways in which one assesses whether or not his or her diet is nutritious.

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