Eating fruit could increase food cravings due to the actions of the simple sugar fructose that provides the foods with their sweetness. These urges can lead people to consume high-calorie foods, ruining the plans of many dieters.
Researchers examined 24 subjects who drank liquids containing fructose and its sister sugar glucose on alternating days. The study found that fructose produced greater desires for sugary snacks than glucose, lending credence to the idea that various forms of sugars produce different cravings. Glucose is typically found in carbohydrate-rich foods such as breads, and is utilized in nearly all biological activities in the body.
Fructose does not stimulate insulin or other hormones that provide a feeling of fullness after eating. This might suggest why subjects consuming the simple sugar crave high-calorie foods. Volunteers were willing to trade financial payments in a month in exchange for the immediate reward of food.
"We gave the volunteers choices between being served tasty food immediately after the study or having money sent to them one month later. When the study participants consumed fructose, they had a greater willingness to give up the money to obtain immediate high-calorie foods, compared to when they consumed glucose," Kathleen Page from the Keck School of Medicine of the University of Southern California (USC) said.
Volunteers in the study were subject to brain scans and blood tests before breakfast. After a drink, they viewed pictures of foods and other objects, while the team conducting the study asked them about their cravings for something to eat. Researchers looked for hormones in blood that could control appetite and cravings in order to measure the effects of one type of sugar versus the other.
Fructose appears to activate the reward center in the brain and could also encourage desires to eat, the study suggests. Combined with the inability of the sugar to trigger insulin and other hormones, this could lead to increased desires for high caloric foods.
People should not avoid eating fruits because of this new study, researchers are stating, as the foods contain many beneficial nutrients and fiber. Fruit juices typically contain high concentrations of sugar, and most people should limit their intake to just one small glass a day, health professionals recommend.
"The best way to reduce fructose intake is to decrease the consumption of added sugar sweeteners, which are the main source of fructose in the American diet," Page told the press.
The effects of fructose versus glucose in food cravings was detailed in the journal Proceedings of the National Academy of Sciences of the United States of America.
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