Herman Pontzer

You can do really intense amounts of work for a day or so, but if you have to last a week or so, you have to maintain less intensity.

We can't push the calories out [value] around too much, our bodies work very hard to keep it the same.

We would say that 'If you want to lose weight, you probably ought to focus on changing your diet and watching how much you eat.' Exercise can help and it's really important [for health in general], but they are two different tools.

Activity monitors are going to be wrong at predicting energy expenditure because they aren't incorporating this adaptation.

Body fat is sort of a long-term signal to the body about how active you have to be and how much food is available, so your body might burn more calories.

We think this is a really common evolutionary adaptation that all animals use to keep from outstripping their resources and to keep from starving. Your body is listening to your environment and setting an energy expenditure level it can maintain.

The women walk six miles a day, the men walk 10 miles; they are super, super active. It's impressive when you're out there with them, and yet their energy expenditures aren't any different than folks who live much more cushy, sedentary lifestyles.