Gina Kolata‘s informative article in Monday’s New York Times about the recent study published in JAMA suggesting that a diet high in fat and protein burns more calories than one high in carbs includes this quote from Dr. Jules Hirsch, emeritus professor and emeritus physician in chief at Rockefeller University:
Perhaps the most important illusion is the belief that a calorie is not a calorie but depends on how much carbohydrates a person eats. There is an inflexible law of physics — energy taken in must exactly equal the number of calories leaving the system when fat storage is unchanged. Calories leave the system when food is used to fuel the body. To lower fat content — reduce obesity — one must reduce calories taken in, or increase the output by increasing activity, or both. This is true whether calories come from pumpkins or peanuts or pâté de foie gras.
To believe otherwise is to believe we can find a really good perpetual motion machine to solve our energy problems. It won’t work, and neither will changing the source of calories permit us to disobey the laws of science.
A calorie is a calorie is a calorie. You can eat better foods, like avoiding simple sugars (because they don’t keep you full as long) and making sure all of your nutritional needs are covered (vitamins and minerals), but in the end, your body takes in calories — simply a unit of energy — and burns them off. Take in less than you burn and you’ll lose weight. Burn more by exercising or being more active and you’ll lose weight. Simple math (though not nearly as simple to actually start counting, and keep counting, right?)