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Fareed speaks with CNN Chief Medical Correspondent Sanjay Gupta about recent research on the risks of high sugar consumption. Watch the video for the full interview.

For 20 years, people have been assuming that fat was the enemy because it produced cholesterol, which was blocking arteries. That's not quite right.

I could talk about this all day long, because I think it highlights some very important things in terms of how we sometimes misinterpret science, or at least exaggerate it.

It was in the late '70s – in fact, there was a Senate commission, Senator McGovern, who actually looked at this issue and found that people who had very high levels of cholesterol tended to die early of heart disease. And there was also other studies that showed if you ate a diet high in fat, it raised your cholesterol. But those were two different studies. And they got really, really linked, not only by the Senate, but also in the scientific community and then by everybody else.

And what happened over the last 30 years, it got codified. It became the way that we eat low fat in this country. And nothing changed. In fact, things got worse. Cardiovascular disease remains the biggest killer of men and women. Diabetes rates are higher than ever before. Childhood obesity. So it didn't work. And I think that's what sort of prompted all this analysis.

I think there's two issues here. One is that fat doesn't get a free pass here. There's still some problems with it. It still raises cholesterol levels. That is associated with heart disease. The problem is that what we replaced fat with was sugar. And sugar may be more problematic, in some ways, for someone who's worried about heart disease than fat.

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If I put a double cheeseburger here and a big sugary drink and I asked anybody, which of these two things is worse for your heart, even a child would probably say the cheeseburger. And almost always they would be wrong. It's the sugary drink that gets converted into that bad cholesterol in our body.

But as you said, the crucial thing to understand is, it's not that fat is good for you, it's that if you replace fat with sugar, it's worse for you?

That's right.

Why is sugar so bad? Is there a simple way to explain that scientifically?

Here's a simple way – it’s that humans weren't designed to eat this much sugar. We used to get sugar once a year when fruit fell from the trees. Even honey was protected by the bees. How much food could you really eat? I mean you can't…10 oranges, that's enough. Now, we eat 140 pounds, roughly, a year, on average. Our bodies simply didn’t evolve to be able to handle that.

So it hits the liver, the liver says I don't know what to do with all this sugar, so it starts to metabolize it in unusual ways and it gets turned into what are known as low density lipoprotein particles. And that's the worst kind of cholesterol.

And for the body, a slice of white bread and a packet of sugar are essentially indistinguishable. The body receives them as the same. White bread – those kind of carbohydrates, for the body, are sugar?

It gets turned into sugar just the same way, and maybe a little bit of a time delay so to speak. But you can trace the sugar, whether it be in that bread or a packet of sugar, and you can find those same particles in those cholesterol particles later on.