Why I Don’t Worry About Sugar

Most of the people I talk to about nutrition are convinced that carbohydrates are their enemy. They think that “sugar spikes” cause diabetes. (They have it backwards. Sugar spikes are the result, not the cause of diabetes!) People seem to be particularly worried about the effects of a sugar called fructose. Personally, I’m not worried about carbohydrates, even fructose, as long as it’s found in an unrefined plant source. I even think that adding a spoonful of sugar or perhaps some maple syrup every now and then could help a lot of people stick to a healthy low-fat, plant-based diet.

Genetically, human beings are almost identical to chimpanzees. Our DNA is almost exactly the same as theirs, which means that our body chemistry is also almost exactly the same as theirs. Since chimpanzees, like many other apes, are mainly fruit-eaters (frugivores), it stands to reason that they probably thrive on a diet that contains a lot of fructose, which is a sugar that is common in fruit. However, the fructose that wild chimpanzees eat is diluted with water and fiber and packaged along with plenty of other nutrients, along with antioxidants and other good things.

Yes, you can make yourself sick by eating too much sugar. However, it would be difficult for most people to get that much sugar from eating fruit! One study found that eating way too much added sugar (at least 25% of total calories!) is associated with only a relatively small increase in the amount of fat (triglycerides) in the blood and a small decrease in the level of HDL (“good”) cholesterol. Of course, if you are having a problem with triglycerides, you should probably cut way back on your consumption of table sugar and high-fructose corn syrup.

Sugar does rot your teeth, at least if you don’t brush carefully after meals. As a result, chimpanzees are prone to dental caries (cavities), just as humans are. However, wild chimpanzees don’t seem to be fat and diabetic and they don’t get heart disease. So why should I imagine that I would get fat and diabetic and suffer from heart disease if I ate a lot of fruit?

Eating lots of sugar does not cause diabetes. Instead, cow’s milk seems to be the culprit in causing type 1 diabetes. A diet that is high in fats and animal protein seems to be the underlying cause in type 2 diabetes.

Eating too many calories from any kind of diet tends to make people gain weight. However, you gain a lot more weight from extra calories from a fatty diet than from extra calories from a high-carbohydrate, low-fat diet. Converting sugar to fat wastes calories. That’s why it’s hard to fatten on carbs but easy to fatten on fats.

Of course, there are a few people with genetic disorders that make it hard for them to tolerate fructose. One of them is hereditary fructose intolerance. Another is fructose malabsorption.

Hereditary fructose intolerance is a potentially fatal genetic disorder that occurs in about 1 out of 20,000 people in European countries. The disorder results from the lack of an enzyme called aldolase B. In people with this disorder, eating anything containing fructose, including sucrose (table sugar), sets off a series of complicated metabolic problems that can ultimately cause liver damage. The only solution is for these people to avoid any foods that contain sucrose or fructose.

Fructose malabsorption is an unrelated problem that is far more common but much less serious than hereditary fructose intolerance. Fructose malabsorption results from the absence of fructose transporters in the cells that line the small intestine. Without fructose transporters, the person cannot absorb fructose from his or her food. Even people who have some fructose transporters might be able to absorb only a limited amount of fructose. The remaining fructose will then remain inside the intestines, where it will be fermented by bacteria. The result is syndrome that looks a lot like lactose intolerance: gas and diarrhea. Fructose malabsorption is a common but often undetected cause of recurrent abdominal pain in children.

Fortunately, I don’t have hereditary fructose intolerance or fructose malabsorption. This means that I can eat as much fruit as I like!


Note: For a clear explanation of how the body handles sugar, see my book Thin Diabetes, Fat Diabetes: Prevent Type 1, Cure Type 2.

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This Just In: Extra Calories Make People Gain Weight!

Eating More Fructose Than Nature Intended Is Also Probably a Bad Idea

I recently read an article about a study that supposedly found that high-fructose corn syrup had a different effect on the body than did “regular sugar.” This made little sense, because high-fructose corn syrup is only slightly higher in fructose than table sugar is. In fact, the study said exactly nothing about any difference between table sugar and high-fructose corn syrup. On the other hand, it did say that drinking a lot of sugar water can make you gain weight really fast.

During digestion, table sugar is rapidly broken down to a 50:50 mixture of two simple sugars: glucose and fructose. High-fructose corn syrup is a 45:55 mixture of glucose and fructose. Not much difference. However, the study wasn’t a comparison of high-fructose corn syrup versus what an ordinary person would think of as “regular sugar,” it compared huge doses of pure fructose to huge doses of pure glucose—a major difference.

In reality, the study showed three things. First, people can gain weight really fast if they drink a huge amount of watery syrup, which provides a lot of calories while doing very little to satisfy the appetite. Second, a calorie is a calorie. People gain weight just as effectively if they get extra calories from fructose or glucose. Third, fructose has different effects on the body’s metabolism than glucose has, but we already knew that. None of these results were surprising, so none of the findings of this study were actually newsworthy to the general public. The journalists who wrote about this story made it sound newsworthy by misinterpreting it.

Thanks to the magic of the Internet and the National Library of Medicine, I was able to find the actual article for myself. The subjects in the study first spent two weeks in a clinical research center, eating “an energy-balanced, high–complex carbohydrate (55%) diet.” Of course, 55% of calories from complex carbohydrates isn’t “high” in complex carbohydrates by my standards, but so what?

After spending two weeks eating the controlled diet, the subjects were sent home for an eight-week outpatient study, in which they were allowed to eat whatever they wanted, as long as they drank enough of a sweetened beverage to give them 25% of their calorie requirements. Some of the subjects were given a beverage sweetened with pure fructose (not high-fructose corn syrup), the others were given a beverage sweetened with glucose.

As a result of guzzling all that sugar water, the people in both groups took in more calories than they needed. In fact, people in both groups took in roughly the same number of extra calories and gained roughly the same amount of extra weight as a result. That wasn’t surprising, although it was interesting that the extra fat tended to get deposited in different places, depending on which kind of sugar was consumed. Nor was it surprising that the fructose beverages caused spikes in the amount of fat (triglycerides) in the blood after meals. Scientists already knew that fructose does that. They’ve also known for decades that high levels of fat in the blood contribute to insulin resistance, which in fact occurred among the people who drank all that extra fructose.

Although the study does suggest that eating too much fructose can be bad for you, it didn’t say anything about whether high-fructose corn syrup was significantly worse than table sugar. In fact, a commentary that accompanied the article said, “It is not known whether the adverse effects of sucrose and HFCS consumption are ‘diluted’ by their lower fructose content relative to pure fructose.” The commentary does make it clear that if you are eating too much fructose, you probably aren’t getting it from eating too much fruit. “One would have to eat vast quantities of fruits every day in order to ingest metabolically adverse amounts of dietary fructose.”

The take-home message for consumers wasn’t clear from the news accounts, but it’s very simple. It’s hard to overdose on fructose from eating fruit, but drinking syrup-water isn’t good for you.