When it comes to weight loss, sugar is the enemy, right? Well, not so fast! Researchers are finding that certain sugars are more responsible for adding pounds. And there may be no bigger culprit than that of fructose. This simple sugar has been found to turn into fat at a remarkable rate; much faster than any other sugar!

In a study published in the Journal of Nutrition, a team of researchers from the University of Texas Southwestern Medical Center (UTSW) has found that the human body transforms fructose into fat more efficiently – and rapidly — than it does other sugars. But this doesn’t automatically mean that high-fructose corn syrup, the key sweetening agent in most processed foods, causes more weight gain than any other sugar. That’s because the researchers focused on simple sugar fructose, NOT high-fructose sucrose or corn syrup, which combine fructose with another sugar, glucose. This sugary combination is actually found in any food with sugar, including healthy fruits.

The study was designed to investigate whether or not fructose was more likely to result in fat development than glucose. In the course of the study, which lasted several weeks, the subjects – six healthy men and women – were fed breakfast drinks that contained three different sugar combinations. Then, the subjects were fed a carefully controlled lunch. The drinks’ sugar make-up was different for each of the three tests:

1. Test One: the drink contained 100% glucose; this is similar to doctors’ oral glucose test to detect diabetes
2. Test Two: the drink was half glucose and half fructose
3. Test Three: the drink was 25% glucose and 75% fructose

The researchers examined to measure how the subjects converted the sugars to fat in the liver. And, they wanted to determine if consuming a sugary meal in the morning influenced the metabolization of foods eaten later in the day. It was shown that consuming breakfast drinks high in fructose led to dramatic increases in “lipogenesis”; this is the process in which sugar is converted into body fat. The findings also demonstrated that fructose eaten with fat, or before fat is consumed, typically resulted in the fat being stored, and not burned.

According to the study’s lead author Elizabeth Parks, PhD, just how glucose affects your body is the responsibility of the liver. While the liver determines whether glucose is stored as fat or burned as energy, fructose follows different rules. “Fructose gets made into fat more quickly, and when that process is turned on there seems to be a signal that goes to the liver that says store all the other fats you are seeing,” she says.

So what are your options? It’s almost impossible to avoid every food without fructose, and therefore sweetness. And truthfully, some foods have more or less fructose than others. For instance, while fruit has fructose, and too much may affect weight loss, its fiber and beneficial nutritional content make it crucial for a healthy diet. “The health benefits of eating fruit far outweigh the slight increase in fat production that might occur as the result of eating something with fructose in it,” says nutritionist Lona Sandon, RD.

How Bad is High-Fructose Corn Syrup?

In regards to high-fructose corn syrup, it’s not all gloom and doom, according to nutritional experts. In fact, high fructose corn syrup, which contains almost equal portions of fructose and glucose, has been shown to moderate certain metabolic effects of fructose. Multiple studies have illustrated that high-fructose corn syrup, has only as many calories as sugar, and is even handled similarly by the body.

More importantly, nutritionists don’t put the blame on any one type of sugar. They advise people who want to lose weight to limit their intake of ALL sugars, not just one kind. “I’ve never had a client who has become overweight eating too much fruit or too many vegetables, but I have had plenty who ate too many foods with added sugar and fat,” says Sandon.