Are Calorie Labels Worthless?

Ever wondered how those calorie numbers that have become all-important to dieters were devised? Well, you can trace the formula back to a 19th century scientist who burned food to measure its energy, then weighed human feces and urine to determine how much of that was excreted, subtracted the two and—voila!—determined a formula that has more or less stood to this day. With science that advanced, it's little wonder that a growing number of modern scientists are questioning his math, Mother Jones reports.

Last week, a panel of scientists presented research indicating that cooking food breaks down its cell structures, making much more of its energy available for the body—meaning that raw, unprocessed food is significantly less caloric than previously thought. The body also consumes more energy breaking raw food down. The energy equation is also affected by your stomach bacteria, which varies from person to person, making true calorie counts a much more complicated question than your average cereal box can handle. (More food stories.)