Burn, Herman Pontzer

The book examines energy expediture, exercise, and diet from an evolutionary perspective, putting the modern converns of health and metabolic disease in a different light than we typically encounter on the covers of wellness magazines or lifestyle books. Every molecule in your body, every pound of bone and muscle, every ounce of brain and kidney, every fingernail and eyelash, all six quarts of blood squirting around your vessels, all of it is made of reassembled bits of food you’ve eaten. The energy that keeps you moving and keeps you alive comes from your diet as well. You are what you eat isn’t just a well-worn cliché, it’s how life actually works. Bottom line is that your daily activity level has already no bearing on the number of calories you burn each day. Our metabolic engines shift and change to make room for increased activity costs, ultimately keeping daily energy expenditure within a narrow window. As a result, physically active people—whether it’s hunter-gatherers living today or

in our collective past, or people in the industrialized world who exercise regularly—burn the same amount of energy as people who are much more sedentary. In other words, if you start a new exercise program tomorrow and stick to it religiously, you will most likely weigh nearly the same in two years as you do right now. You should still do it! You’ll be happier, healthier, and live longer. Just don’t expect any meaningful weight change in the long term from exercise alone. Exercise is a tool for achieving weight loss… it seems to help people maintain weight loss.