Fructose, the industrial sweetener used liberally in the manufacture of soft drinks and processed foods, has been singled out as a prime suspect in America’s obesity epidemic. Scientists have theorized that fructose makes people store fat and gain weight faster than other carbohydrate sources. But a recent study suggests that excess calories in any form, not just fructose, are what pack on the pounds.
How bad is fructose?
Is fructose really hazardous to your health, or is a calorie just a calorie? To find an answer to that question, Dr. John Sievenpiper, a research fellow at St. Michael’s Hospital in Toronto, conducted an analysis of 41 previous fructose studies. He found that sugar in the form of fructose affected people no differently than other carbohydrates.
Sievenpiper’s team reviewed 31 studies that compared weight gain in participants who ate the same number of calories with diets either high in fructose, or high in a different carbohydrate such as starch or glucose.
The fructose study review
The studies included people who were either normal weight, overweight or obese. Diets in the study were designed for weight loss, while others were intended for maintenance or weight gain. Over an average of four weeks, there was no difference in weight loss or gain between the two groups.
Ten other studies separated participants into two groups and fed them the same diet with an equal number of calories. Extra calories in the form of fructose were fed to participants in one of the groups. After an average of one and a half weeks, the fructose group gained a little over a pound more than the control group. Sievenpiper noted that while the higher dose of fructose was associated with weight gain, it was impossible to determine whether the excess pounds were a result of fructose alone, or the extra calories.
It’s all about the calories
The results suggest it’s not the fructose itself that causes weight gain, but calories in general. However, the studies reviewed did have flaws. None of them examined participants’ insulin levels, which is important because other studies have suggested that because of the way fructose is processed in the liver, people who eat a lot of it may be more likely to become insulin-resistant. The studies Sievenpiper’s team reviewed also didn’t look into how the weight that was gained was distributed. Other studies have suggested that fructose creates belly fat—the worst kind of fat—more than other carbohydrates.
Don’t worry about fructose?
To get a better handle on whether fructose is as bad as its reputation, the researchers recommended larger studies with a longer duration. It would also be helpful if the difference between industrial fructose and the fructose that occurs naturally in fruits and vegetables were examined scientifically. But in the meantime, consuming a moderate amount of fructose, which is hard to avoid, probably won’t make you fat, as long as you only consume as many calories as you need to maintain a healthy weight.