Why is it a problem to have too much sugar?

Many nutrition experts say that sugar in moderation is fine for most people.  But in excess it can lead to metabolic problems beyond its effects on weight gain.  The reason, studies suggest, is fructose.  Any fructose you eat is sent straight to your liver, which specializes in turning it into droplets of fat called triglycerides.

“When you ingest fructose, almost all of it is metabolized by the liver, and the liver is very good at taking that fructose and converting it to fat,” said Dr. Mark Herman, an assistant professor of medicine at Harvard. Studies show a predictable response when people are asked to drink a sugary beverage: A rapid spike in the amount of triglycerides circulating in their bloodstreams. This also leads to a reduction in HDL cholesterol, the so-called good kind.

Over time, this combination – higher triglycerides and lower HDL – is one major reason sugar promotes heart disease, said Dr. Aseem Malhotra, a cardiologist and adviser to the United Kingdom’s national obesity forum. This sequence of events may even overshadow the effects of LDL cholesterol, the so-called bad kind.

“What many people don’t realize is that it’s triglycerides and HDL that are more predictive of cardiovascular disease than LDL cholesterol,” Dr. Malhotra said. “I’m not saying LDL isn’t important. But if there is a hierarchy, triglycerides and HDL are more important than LDL.”

Dr. Malhotra said that when people reduce their sugar intake, “their overall cholesterol profile improves.”

“I see this in so many of my patients,” he added. “The effects are rapid.”