Many low-carb diets advocate eating hamburgers without the bun to avoid the carbohydrates from all that bread. However, some hamburger buns bring nutrition with them to the table. Others are less nutritious. Although there are hundreds of styles and brands, three basic types offer a representative sample of what's available.
Serving Size and Calories
Health resource website MyFitnessPal provides information for three different styles of bun: enriched white bread, whole wheat and the "classic" white bun. In all three cases, the serving size is one bun. Both classic and enriched white buns have 110 calories per serving, while a whole wheat hamburger bun contains 130 calories.
The three types of hamburger bun carry roughly the same amount of carbohydrates, 20 to 25 grams per serving. However, Walter Willett, Harvard nutritionist and author of "Eat, Drink and Be Healthy," reports that it's not the amount, but the kind of carbs that's important. The classic buns contain just 1 gram of dietary fiber and 3 grams of sugar per serving. Enriched buns have the same low level of fiber with 1 gram of sugar. Whole wheat buns deliver four times as much dietary fiber per serving. White breads use refined grains, meaning the energy stored in their carbohydrates acts much more like sugar than like the healthful, complex carbohydrates in whole wheat buns.
An enriched white hamburger bun contains no appreciable amount of fat. Classic white buns contain 2 grams of fat per serving, including 1 gram of healthy unsaturated fat. Whole wheat buns also contain 2 grams of fat, divided between 1 gram each of unhealthy saturated fat and healthy unsaturated fat. According to Dr. Mehmet Oz in "You: The Owner's Manual," the ratio of healthy to unhealthy fat is what to look for when considering a food's fat profile.
A whole wheat hamburger bun has 6 grams of protein. The enriched white and classic white each contain 3 grams per serving. Because these come from wheat flower, they are incomplete proteins. They contain only some of the amino acids your body needs for optimum tissue health. Note that some enriched breads are enriched with soy protein, which is a complete protein.
Classic hamburger buns contain 10 percent of the USDA daily recommended allowance of calcium, and 6 percent of the iron. Enriched bread, which uses less milk, contains only 2 percent of your calcium and the same amount of iron. Whole wheat buns contain no calcium, but 8 percent of your daily recommended iron per serving.