Skip to main content

Verified by Psychology Today

Martina M. Cartwright

Martina M. Cartwright Ph.D., R.D.

Does Soda Make You Fat?

A closer look at fructose facts.

Chances are if you grew up in the last century, you’ve consumed a soda, or "pop" for those of you located in the upper Midwest region of the U.S. Sugar-sweetened, carbonated beverages have been around since the late 1800s. High fructose corn syrup (HFCS) was added to most sodas in the mid-1980s and is now the most common added sweetener to pre-packaged sweetened beverages in the United States. If you buy a soda in another country, it’s probably still sweetened with cane sugar.

Fructose is sugar from fruit. It’s the main sugar in all fruits and vegetables, including corn. Fructose is less expensive to produce than cane sugar so it is used as an industrial sweetener. HFCS is 55% fructose and 45% glucose. You can find it in everything from sodas, to popular “hunger-crushing” diet shakes. Yes, it’s true. Take a look at some popular weight loss shakes and you will see the primary sweetener is in fact, fructose.

Animal research suggests that consuming pure (meaning 100%) fructose can lead to weight gain due to changes in blood-sugar controlling hormone insulin and appetite controller leptin. In humans, it isn’t clear if HFCS promotes overweight and obesity. There is a correlation between increased soda consumption and obesity, but sedentary lifestyles and larger portions of everything have skyrocketed, too.

Some research suggests that “liquid sugar” is less satisfying than solid sugar found in fruit, vegetables, etc. Fruits and veggies contain fructose and complex carbohydrate in the form of fiber. Fiber can satisfy, but if liquid fructose is such an appetite inducer, then why is it the primary sugar ingredient in many weight loss shakes? The answer to obesity isn’t as simple as blaming soda. Fructose is a natural sugar and there are those who argue that humans shouldn’t consume it at all. However, what is likely true is that excess fructose or sugar of any type will likely contribute to weight gain. This includes sugars from non-carbonated beverages and “natural” foods.

When it comes to obesity, putting the blame on squarely HFCS beverages is misleading. Those of us in the field of nutrition who are familiar with the body of evidence view all studies, whether funded by industry or government NIH grants, with a critical eye. All research must be funded by some entity, and the key is to separate agenda from fact, good science from bad, rats from humans, correlation from cause, and to carefully interpret the results. Much of the fructose research has been conducted in animals or involved the use of 100% pure fructose in large doses. The notion that fructose, regardless of the amount consumed, causes fatty liver in humans is still theory. Moreover, most studies refer to "excess" fructose consumption. The idea that excess fructose is a culprit in obesity is still under investigation.

The point is, if someone wants to consume a soda or HFCS beverage every once in a while, they should be able to do so. Fear tactics and cherry-picked science do little to educate the consumer. The take-home message is that a 12-ounce can of pop contains about 140 calories and 39 grams of sugar; a 20-ounce serving has 240 calories and 65 grams of sugar, and a bottled coffee frap drink from a popular vendor has 32 grams of sugar in 9.5 ounces. If you want to enjoy the beverage, you have to “burn it to earn it.” For example, one 20-ounce soda contains the same amount of fructose as five bananas. The college football players I used to counsel would consume a bunch of bananas and a half-gallon of 2% milk while watching films; they would subsequently burn it off.

Just like a financial budget, we all have calorie budgets. If you go over, then you gain weight; if you consume less or burn off the calories with exercise, then your weight will decrease or stay the same. Until we learn more about the universal effects of HFCS on individual human metabolism (how the body processes it), then it seems to be OK for consumers to drink an occasional beverage while being mindful of the caloric content and the influence it has on their individual appetites. If you are concerned that soda or other sugar-sweetened beverages is making you gain weight, cut down, limit (but don’t eliminate), and replace an HFCS beverage a day with a lower-calorie alternative like a handful of carrots or a glass of water.

Many of us who understand the body of scientific evidence and who’ve routinely counseled people struggling with personal weight management choices recognize that providing consumer nutrition education is only half the battle. Personal responsibility is a choice that cannot be legislated. Some state and municipalities have proposed laws to not only tax sodas and sugar-sweetened beverages but to ban them. Individual motivation and education, not taxes or bans, do more to promote long-term behavioral changes that curb obesity. The government needs to stop behaving like Schneider from the ‘70s sitcom “One Day at a Time,”—that is, constantly interfering in personal business—and leave the dietary decision making to the individual.


Akhaven T. et al. Effect of drinking compared with eating sugar or whey protein on short term appetite and food intake. Int J Obes 2011. 35(4)L562-9.

Drewnowski A and Bellisle F. Liquid calories, sugar and body weight.Am J Clin Nutr 2007:85:651-61.

Klurfeld DM et al. Lack of evidence for high fructose corn syrup as the cause of the obesity epidemic. Int J. Obes. 2013;37(6):771-773.

Pan A and Hu FB. Effects of carbohydrates on satiety: differences between liquid and solid food. Current Opin ///clin Nutr Metab Care 2011;14:385-90.

Rippe J. The health implications of sucrose, HFCS and fructose: what do we really know? J Diabetes Scie Technol. 2010;4:1008-1011.

Slavin J. Nutr. Beverages and body weight: challenges in the evidence based review process of the Carbohydrate Sub committee from the 2010 dietary guidelines advisory committee. Rev. 2012. Nov 70S:s111-20.

Tappy L and Le KA. Does fructose consumption contribute to non alcoholic fatty liver disease? /clin Res Hepatol Gastroenterol 2012;36:554-60.

White JS et al. High fructose corn syrup: controversies and common sense. Am. J Lifestyle Med. 2010; 4:515-20.

White JS. Straight talk about high fructose corn syrup: what is and what it ain’t. Am J Clin Nutr. 2008;88:1716s-1721s.

Zhu Y et al. The effect tof food form on satiety. Int J Food Sci Nutr. 2013. 64(4)L385-91.

Zhu et al. PLoS One. 2013;20:8:e67482.


About the Author

Martina M. Cartwright

Martina M. Cartwright, Ph.D., R.D., is an adjunct professor of Nutritional Sciences at the University of Arizona and an independent biomedical consultant.


My website, LinkedIn