You’ve probably noticed that sugar’s been getting a pretty bad rap lately. For weeks now, this video of Robert Lustig, an expert on child obesity at the University of California, San Francisco and a subsequent New York Times Magazine cover story have been making the rounds.
In a nutshell, the links argue that both sugar and high fructose corn syrup are much more harmful than other substances because they contain high levels of fructose (50% or more), which is metabolized primarily in the liver (as opposed to other similar compounds like glucose, which are metabolized by every cell in the body). When we eat more sugar than the liver can keep up with metabolically, it starts converting the fructose directly to fat, which experts think can trigger insulin resistance. We release insulin is to control blood sugar, so when our bodies stop responding to insulin, blood sugar goes up, and diseases like diabetes, metabolic syndrome, and (because insulin helps existing tumors grow) even cancer can follow.
Scary stuff. But what’s important to keep in mind is that this doesn’t happen always and without fail. If you’re eating a healthy diet, some sugar is just fine. Even helpful, as Gretchen Reynolds noted in a recent blog post for the Times. Apparently, in athletes, some fructose can actually help the liver recover from a workout. All this, of course, leads me to this question: For those of us who are active and trying to eat well, where’s the cutoff? How much sugar counts as acceptable–and how much is too much?
A bit of nosing revealed that there are precious few recommendations for sugar. The USDA says that added sugars should make up only six to 10 percent of your daily calories. But this is pretty useless information, especially since both added and naturally-occurring sugars are lumped together on labels.
Other things that aren’t taken into account on nutrition labels: 1) The ratio of fructose, compared with less harmful sugars like glucose (sometimes called dextrose), lactose, etc. 2) How all the sugars are being delivered. If they’re coming in an apple, for instance, our bodies needs to break them down first (and the fiber helps slow down the process even further). If they’re in juice, it’s straight into our systems.
Conclusion: Here again the “look for whole foods, from natural sources,” rule comes in quite handy. Scanning an ingredient list to see where the sugars on the food label may be coming from is another useful one, as is taking note of how much metabolism-regulating fiber you’re bundling in there.
But now, on to the bigger question. On her excellent Food Politics blog nutritionist Marion Nestle has this to say about a 2009 American Heart Association report on sugar habits: “Americans eat way too much, it says, a whopping 22 teaspoons a day on average. Let’s work this out. A teaspoon is 4 grams. A gram is 4 calories. So the 275 calories in that default 20-ounce soda [bottle] you picked up from a vending machine come from nearly 17 teaspoons of sugar – close to the average right there.”
I really like Nestle’s visual, almost gut-instinct approach. By dividing the grams of sugar any food has by four, you can get a number with some real-world references. Elsewhere, Nestle’s said that anything with 14 grams of sugar or above should be treated as a dessert. Thinking of it as 3.5 teaspoons, that more than makes sense.
In terms of additional specifics, I also asked nutritionist Stephanie Middleberg for her take. Consistent with the above, she says, ”the sugar answer really depends on what food and what form (meaning natural sugar verses added). For example, fruit naturally contains roughly 15g per serving (but I consider this healthy sugar).” Below, she’s sketched out four useful guidlines:
Yogurt: “I recommend keeping to under 15g. Yogurt naturally has about 8-10g. A fage 2% plain greek yogurt has 8g but greek yogurt tends to be lower in sugar than other brands. In this case, anything over 15g is considered more of a dessert.”
Cereal: “Try to keep it under 6g. Once you head into the double digits I consider it closer to a dessert.”
Bars: “I recommend keeping to under 12g sugar.”
General: “Once you head into the 20g of sugar, that is getting high. Typical coke can=27g”
…To put this all in even more context, here are a few blogs and sites I thought did a great job of breaking out some of the finer points:
1) On Foodtrainers, nutritionist Lauren Slayton tackles the topic of fruits (which are quite high in fructose) for dieters.
2) See how some common foods rate in this WebMD piece.
3) For some creepy sugar cube visuals, check out SugarStacks.com.