Is your favorite energy bar all it’s cracked up to be? Maybe not, according to a review of the contents of 30 popular energy bars.

ConsumerLab.com, an independent evaluator of dietary supplements and nutrition products, conducted a nutrition bar product review, testing 30 bars to ensure that their label claims matched the nutritional content of the bars. The testing showed that an alarming 60 percent of the products did not meet their label claims, with only 12 products passing the review.

Undeclared carbohydrate was the most common problem with half of the products exceeding the claimed levels of carbohydrates by as much as 20 grams. Ironically, many of these bars claim to be “low carb.” A possible explanation for the carbohydrate discrepancy might be because some manufacturers do not count the ingredient glycerin—used to add moisture and sweetness—as a carbohydrate, though the U.S. Food and Drug Administration (FDA) requires it to be counted as a carbohydrate. The FDA has sent warning letters to some manufacturers asking them to correct their labels or face legal action. Also, FDA has warned manufacturers that the term “low carb” is not an authorized content claim and should not appear on labels.

In addition to the carbohydrate mislabeling, seven products contained more sodium than stated on the labels, two products exceeded the total amount of fat by 1.5 and 3 grams and four products had higher than claimed amounts of saturated fat.

On this same mislabeling issue, the National Consumers League and the Consumer Federation of America wrote a joint letter to FDA asking the federal agency to continue its scrutiny of energy bar manufacturers that routinely mislead consumers about their bars’ nutritional contents.

A complete list of bars that passed ConsumerLab’s review are available to online subscribers at www.consumerlab.com.