To determine “low fat” and “low sugar,” BMJ researchers used European Union regulations: 3 grams of fat per 100 grams or less of yogurt, 1.5 grams or less for drinks, and a maximum of 5 grams of total sugars per 100 grams.
For this study, researchers looked at the nutritional content of 921 supermarket yogurts and yogurt products. The products were then divided in to eight categories: children's; dairy alternatives, such as soy; desserts; drinks; flavored; fruit; natural/Greek; and organic.
The worst offenders were products in the flavored, fruit, organic and children's categories, which had a median sugar content between 10.8 and 13.1 grams per 100 grams. As Popular Science pointed out, "100 grams is about 3.5 ounces, and a standard yogurt cup in the U.S. is 5 or 5.3 ounces."
That means one of those tiny yogurt cups is giving you about half your recommended sugar intake for the day. The recommended daily sugar intake is 25 grams for women and 38 grams for men.
The unsweetened, plain yogurts — Greek and natural — contained only 5 grams of sugar per 100 grams of product, which is healthy.
BMJ researchers found that "while yogurt may be less of a concern than soft drinks and fruit juices, the chief sources of free sugars in both children and adults' diets, what is worrisome is that yogurt, as a perceived 'healthy food,' may be an unrecognised source of free/added sugars in the diet."
They concluded that "not all yogurts are as healthy as perhaps consumers perceive them, and reformulation for the reduction of free sugars is warranted."
Popular Science compiled data from U.S. markets as a comparison. The healthiest yogurts in its study were Chobani whole milk plain and Chobani nonfat strawberry, with 5.0 and 5.3 grams of sugar, respectively.
The worst offenders were Brown Cow whole milk strawberry and Dannon lowfat strawberry on the bottom yogurts. Each contained 22 grams of sugar, or nearly an entire day's recommended intake.