'Tis the season to eat sweets â€” perhaps too many. And the use of one ubiquitous sweetener, high-fructose corn syrup, is particularly controversial.
But earlier this month, several scientific papers concluded that high-fructose corn syrup isn't any worse than table sugar when it comes to gaining weight. So our love affair with either kind of sugar is problematic.
Let's start with a question that's easy to answer: Does Olympian swimmer Michael Phelps need to worry about what type of sweetener â€” or how much of it â€” is in his pancakes?
No, says Elizabeth Parks, professor of nutrition at the University of Texas Southwestern Medical Center in Dallas. Different kinds of sugars will not make a difference in his case. With the amount of training Phelps does, he's burning calories like mad.
"That's an extreme example, but he's able to use those for energy efficiently," Parks says.
Most other people â€” who don't have the muscle mass, metabolism or youth of Michael Phelps â€” are eating too many refined sugars. And nutritionists say this is not good.
"This is the hard part," says Parks. "At what level do we need to be careful of the intake of our sugars?"
All the empty calories that come from sugars have no doubt helped expand waistlines globally, says researcher Barry Popkin of the University of North Carolina, who studies obesity around the world.
Popkin says a critical component in the increase of the average weight in many countries is caloric beverages, such as soft drinks, juices and sports drinks.
Several years back, Popkin began to wonder if high-fructose corn syrup â€” used to sweeten many of these drinks â€” was of particular concern.
He says that before 1970, the world consumed a trivial amount of high-fructose corn syrup.
But when refined corn syrup became abundant and cheap, production exploded.
"All of a sudden, we're consuming dozens or hundreds of grams of this a day, depending on the individual, and so you have to raise questions," he says.
Table sugar, made from sugar beets or cane, is a combination of two sugars: glucose and fructose. And so is high-fructose corn syrup.
So from a molecular point of view, table sugar and high-fructose corn syrup look very similar. But they're metabolized differently.
"Let's look at the effect on human health," Popkin says. "That's what counts."
In the past few years, scientists have done a lot of research on how sugars work in the body. And they have some evidence that our bodies convert fructose to fat faster than we turn other sugars into fat. But remember, both table sugar and high-fructose corn syrup contain fructose.
Popkin says with all the new results, he's now convinced that too much of either sweetener leads to obesity, and that high-fructose corn syrup isn't any worse than regular sugar.
"I would admit that we don't have an obesity effect," says Popkin, "and I was the one who posed it before. And now we have studies to show we don't have that."
But the case isn't closed when it comes to other possible health effects.
Richard Johnson, a researcher at the University of Colorado, is interested in how sugars are metabolized.
Table sugar, he explains, enters the body with the glucose and fructose molecules bonded together. Enzymes in the gut have to separate them.
But with high-fructose corn syrup, the two sugars are not bonded, so there are different absorption characteristics, he says. "So it's theoretical that it could lead to differences in manifestation of metabolic syndrome and other conditions. And we're studying that."
So if you've followed this sugar chemistry lesson, excellent. If not, here's the take-home message: If you look more like the average Joe than Michael Phelps, you might do well to cut back on sugary drinks and sweets of all kinds.