All Calories Aren't Equal

The New York Times published an article today titled “Why Processed Foods Make You Fat.” It was about the results of a recent controlled study (the first of its kind) conducted by the National Institutes of Health in which 20 healthy men and women (average age 31) were fed two different diets for four weeks while living in a research facility. The group ate ultra-processed meals and snacks (defined as having ingredients predominantly found in industrial food manufacturing, such as hydrogenated oils, high-fructose corn syrup, flavoring agents, and emulsifiers) for two weeks (items like bagels, cold cereal, turkey sandwiches, French fries, low-fat chips, sweetened yogurt and diet beverages) and then were fed unprocessed foods for two weeks (fresh produce, beans, nuts, oatmeal, grains, grilled chicken, beef and fish and other whole foods). The two diets contained the same amounts of calories, carbs, fats, sugars, protein, salt and fiber and the subjects were allowed to eat as much as they wanted.

What happened? The processed diet caused the subjects to eat an extra 500 calories a day, leading them to gain an average of 2 pounds in 2 weeks. On the unprocessed diet, the subjects ate less and lost weight. The reason: Processed food caused a rise in ghrelin, the hunger hormone, and a reduction in the appetite-suppressing hormone PYY. On the unprocessed diet, the opposite happened: gherlin went down and PPY increased.

According to the study’s lead author, “This is the first study to demonstrate causality—that ultra-processed foods cause people to eat too many calories and gain weight.”

Processed food is engineered to make you keep eating it, plus the simple carbs that make up foods like cold cereal, white bread and chips are digested so quickly that you end up hungry again soon after eating them. A single serving of potato chips (135 cal, 9.4 g fat) and a 1/2 an avocado (130 cal, 12 g fat) may look similar on paper, but the chips have no nutritional value and won’t keep you full. Avocados are loaded with healthy fats and filled with fiber. Don’t base your food choices on calories or fat grams; always choose real, unprocessed (preferably organic) foods and you won’t have to worry about calories or fat content.