No one thinks of a piece of layer cake as a diet item. But it turns out that even conscientious label readers may overestimate the size of a single serving and underestimate the number of calories they’re eating.

Researchers at Cornell University’s Food and Brand Lab looked at dozens of packages of dry cake mixes. They found that, while nutritional labels give the calorie count of a specific amount of unfrosted cake, the photo on the front often shows a larger piece plus enough frosting to more than double the listed calories.

The researchers also surveyed different groups of women for their study and even those who work in the food industry overestimated serving size because of photos on the packages.

Can you have a reasonably sized slice of cake while on a diet? It’s possible when you make your own simple cake from scratch. For instance, light and airy angel food cake is made with egg whites and has just 150 calories for one-twelfth of a 10-inch cake.

A drizzle of pureed berries with or without a dollop of thick Greek yogurt makes a healthy alternative to frosting. When you want something sweeter, keep in mind that a thin glaze has fewer calories and none of the fat of a frosting.

Another option is baking a meringue-based cake called a dacquoise, made from stiffly beaten egg whites enhanced with ground nuts in place of flour. It has more calories per serving than angel food cake, but it also delivers the health benefits of almonds, walnuts or hazelnuts, depending on the type you choose, plus a great nutty flavor.

More information

The U.S. Department of Agriculture has a simple and inexpensive angel food cake recipe on its website.