The next step is to determine the amount of sugar, which falls under Total Carbohydrate on the label. To get a clearer mental picture of just how much sugar is in the item, Lanzano recommends dividing the grams of sugar by four, which equals the number of teaspoons in a serving. My favorite energy bar has 21 grams of sugar. That means the one-serving bar has — surprise! — more than 5 teaspoons of sugar. Although eating that much sugar in a sitting doesn't sound appetizing, it's not uncommon, says Lanzano. But it's not advisable: Added sugar intake shouldn't exceed 10 percent of daily calories, or 12 teaspoons (48 grams) per day for the average 2,000-calorie diet, she says. This includes the refined sugar found in bars, cereals, soy milks, soft drinks, and so on, not just the sugar you add to your coffee. (Note: Not everyone's needs match the average 2,000-calorie daily intake. To determine your requirements, go to bcm.edu/cnrc/caloriesneed.htm and type in your sex, height, weight, age, and activity level.)

The quantity listed on the label doesn't tell the whole story, either. “Sugar amounts don't distinguish added sugar from natural sugar,” says Lanzano. In fact, added sugars and naturally occurring sugars (such as those in milk) appear in the same number on the label. And your added limit doesn't include the sugars found naturally in, say, fruit. For example, dried fruit, such as dates or fig paste found in some energy bars, has a substantial amount of natural sugar, yet its fiber slows down absorption. Other less-processed sugars may have some benefit — brown rice sweeteners may include fiber; honey has beneficial antioxidants and boosts immunity; and molasses has calcium, potassium, iron, and magnesium — but any concentrated sugar source can spike blood sugar and lead to energy crashes, warns Lanzano. If you have to choose one, go with a fruit or unprocessed sugar source, such as agave nectar, which has a lower glycemic index and so metabolizes more slowly than other sugars.