Fructose does not make you gain more weight than other types of carbohydrates, Canadian researchers reported in the Annals of Internal Medicine. They found that a little extra fructose added to foods did not trigger weight gain, as long as the participants reduced the equivalent total calories from other carbs. In other words, fructose calories are no more fattening than the same number of calories in other carbohydrate foods.
The authors explained that fructose's contribution to excess bodyweight in Western societies is often mentioned, but no studies have clearly shown a connection. John L. Sievenpiper, MD, PhD., and team set out to determine what effect fructose might have on people's weight in controlled eating trials.
They gathered data on 41 controlled feeding trials which had lasted for at least seven days. 31 of them, involving 637 participants, compared the effect of free fructose and non-fructose carbohydrates in isocaloric trials. Isocaloric means with similar total calories. 10 studies, involving 119 participants were hypercaloric trials (high calories). They excluded trials that evaluated high-fructose corn syrup (42% to 55% free fructose).
They found that in the isocaloric trials, fructose made no overall difference to body weight, when compared to non-fructose carbohydrates. However, high calorie fructose diets did lead to increases in body weight.
Put simply: when people ate foods with fructose, and their meals had the same number of calories as people's with non-fructose carbohydrate, there was no significant different is body weight. However, high calorie fructose diets did make people put on weight.
The authors stressed that several of the trials available were not of very good quality. They suggested that in the fructose hypercaloric trials, weight gain may have simply been due to too many calories, rather than fructose itself.
In an Abstract in the same journal, the researchers concluded:
"Fructose does not seem to cause weight gain when it is substituted for other carbohydrates in diets providing similar calories.
Free fructose at high doses that provided excess calories modestly increased body weight, an effect that may be due to the extra calories rather than the fructose."
What is fructose?Fructose is also called fruit sugar or levulose. It is found in many plants. Fructose, along with glucose and galactose, is one of three dietary monosaccharides - they are absorbed into the bloodstream during digestion. A monosaccharide is the smallest possible unit of sugar.
Pure fructose, in its dry form, is an odorless sweet, white, crystalline solid - it is the most water-soluble sugar. Fructose is found in honey, berries, the majority of root vegetables, and vine fruits. Commercial fructose typically comes from sugar beets, sugar cane, and corn. Fructose, in various forms, is commonly added to foods and drinks to make them taste better.
Written by Christian Nordqvist