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Staying Skeptical Of The Sugar Wars
April 07, 2003
Maia Szalavitz
The LA Times misses the bigger controversies

The Los Angeles Times has an in-depth look at the latest candidate to replace fat as the evil food that behind the obesity epidemic: high fructose corn syrup.

The top of the article features the critics who demonize the sticky liquid; the second half debunks those fears, quoting Marion Nestle, the aptly-named chair of the Department of Nutrition and Food Studies at New York University: “Nutrition 101: Sucrose is glucose plus fructose stuck together. Corn sweeteners are glucose and fructose separated. It is hard to imagine that it makes much difference physiologically.”

Throughout the article, all the experts agree sugary diets are bad for you, no matter what type of sugar it is. However, the mechanisms involved do not seem to be understood well enough to support that conclusion. There is a major paradox, which the article does not discuss and which suggests that people should continue to be skeptical about nutritional advice based on particular food types. No one can argue against the idea that moderation and variety are the watchwords for diet; but the evidence against sugar is filled with controversies.

For example, those who say that high sugar diets are detrimental often point to the way sugar rapidly raises blood insulin levels and claim that this leads to a quick high and then a low blood sugar crash, which results in intense hunger.

But fructose actually raises insulin levels less sharply than sucrose (table sugar) does, and this should be good for decreasing hunger and thereby food intake, according to this theory. Not so, says a 2002 review published in the American Journal of Clinical Nutrition and cited in the L.A. Times story. Insulin seems to affect appetite via leptin. Low leptin levels are associated with greater appetite (though leptin alone doesn’t make a very good weight loss drug except in people who are born deficient). Since fructose causes less insulin to be released than table sugar does, it also has less of an effect on leptin, which means that it could leave people feeling hungry faster because higher leptin levels are never achieved.

Of course, this means it cannot also be true that ordinary sugar, by raising insulin and leptin levels quickly, makes you hungry faster than foods which affect these levels more gradually – if the mechanism is a regulator of appetite in and of itself, it cannot make you equally hungry from fast, sharp rises and low, slow ones. Another factor must be involved, which may or may not be differentially affected by different types of sugar or by sugars in comparison with other foods.

Nutritional science is a field that has long suffered from an excess of theories and a lack of good research. More study is clearly needed.
related links:

Here’s a good review of the effects of sugar on health (with a particular focus on cardiovascular disease)


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