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Food for Thought Food for Thought

Diet Soda -- Is it Really an Alternative?

April 04, 2014

By Emily Finnan, B.S.
Brigham and Women's Hospital

The first carbonated soda was bottled in 1835. Since then, the number of people drinking soda, or "pop" as Midwesterners like to call it, has skyrocketed. Today, Americans drink many sugar-sweetened beverages, such as soda, fruit-flavored drinks and energy drinks. On average, we consume an extra 278 calories each day from these drinks.  Between the 1970s and 2000, Americans more than tripled the amount of sugary drinks they consumed. During this same time we have seen almost a doubling in the incidence of obesity. 

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Not So Sweet Soda

Recently, researchers have looked at whether drinking soda is linked to obesity. Multiple studies have shown that people who drink the largest amounts of soda are more likely to gain weight than people who drink the smallest amounts. Obesity is a risk factor for heart disease, the top killer of Americans. The American Heart Association has recognized this trend. It recommends no more than 150 calories (9 teaspoons) a day from added sugars for men, 100 calories a day (6 teaspoons) for women, and no more than 3 teaspoons or 50 calories for children ages 4 to 8 years old. One 20-ounce bottle of soda can contain as many as 20 teaspoons of sugar! 

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Enter "Diet" Soda

The first diet soda appeared in the 1950s. Since its arrival, diet drinks have soared in popularity. The percentage of adults who drank diet beverages increased from 18% to 24% between 1998 and 2008. 

Diet soda is made from artificial, "non-nutritive" sweeteners. These provide few to no calories. Examples include acesulfame-K, aspartame, neotame, saccharin and sucralose. These sweeteners are hundreds of times sweeter than sugar. So a little bit goes a long way. (For more details about artificial sweeteners, see "How Sweet it Is: An Update on Artificial Sweeteners.") 

Here's a comparison of 20 ounces of regular and diet sodas:


Regular Coke

Diet Coke

Regular Mountain Dew

Diet Dew

65 grams of high-fructose corn syrup
0.3 grams of aspartame, Acesulfame-K
77 grams of high-fructose corn syrup
0.23 grams of aspartame, Acesulfame-K, Sucralose

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Mixed Reviews on Diet Soda

Diet soda may seem like a perfect alternative to regular soda, if you're trying to lose or maintain weight. In one study of overweight and obese people, researchers replaced soda with diet soda or water. People who drank diet soda lost more weight in six months than did people who didn't make any changes to their soda intake. So, switching to diet soda from regular soda can decrease caloric intake, and possibly lead to weight loss. 

However, researchers are starting to find that people who drink diet soda are still at risk for weight gain, type 2 diabetes, heart disease and metabolic syndrome, compared with people who don't drink diet soda. One study found that people who drank more than 3 diet drinks per day were twice as likely to be overweight or obese, compared with people who drank none.  This was an observational study. It doesn't mean that diet drinks cause weight gain.

A recent study focused on diet drinks and heart disease in women. Women who drank 2 or more diet drinks a day were 30% more likely to have a heart disease event (like a heart attack) and 50% more likely to die from heart disease, compared with women who drank fewer than 4 diet drinks per month. The findings were presented March 30, 2014 at the American College of Cardiology’s 63rd Annual Scientific Session in Washington, D.C.

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What the Science Says

Artificial sweeteners aren't processed in our brain like sugar is. And they don't lead to the release of the same hunger hormones as sugar does. But do they affect weight gain? Scientists are working on answering this question. 

In one study, rats were given artificially sweetened food or food sweetened with sugar. The rats given artificial sweeteners ate more and gained more weight than the rats who ate the sugar-sweetened meals. It could be that artificial sweeteners interfere with the body's natural ability to count calories based on how sweet a food is. Your body thinks that other sweet foods don't have as many calories either. So you may overeat sweet foods and drinks.

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What Are Your Choices?

More research is needed to find out how long-term diet soda drinking affects weight.

The ideal solution is to focus on naturally low-sugar beverages, such as

  • Water: If you want flavor, you can flavor your water with a splash of fruit juice or a squeeze of fresh fruit
  • Iced or hot tea
  • Diluted 100% juice: Mix 2 to 3 ounces juice with 2 to 3 ounces water and you'll get half the sugar and calories
  • Low-fat milk: Low-fat milk has half as much sugar as soda does and lots of nutrients, such as calcium and vitamin D
  • Unflavored seltzer/sparkling water: These are great when you need some fizz. Add 1 to 2 ounces of fruit juice for flavor.
  • Coffee: Hold the sugar and drink coffee in moderation (maximum 4 cups/day). Too much can lead to some unpleasant symptoms, such as insomnia and upset stomach.

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The Last Sip

For the soda "addicts" out there, moderation is key. Consider slowly decreasing your intake of both diet and regular soda. Try switching from a 20-ounce bottle to an 8-ounce can. Then gradually eliminate soda from your diet. Or make it an occasional treat. Only you can make the decision about what to drink. The power is in your hands!

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Emily Finnan graduated with a bachelor of science in dietetics from Michigan State University and is currently a dietetic intern at Brigham and Women's Hospital. In her spare time she enjoys exploring Boston and experimenting with plant-based cooking.

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