Cooked Meat Provides More Energy

Harvard researchers have demonstrated for the first time that cooked meat provides substantially more energy than raw meat, highlighting inaccuracies in current food labeling methods.

The research also reaffirms the crucial role that cooking played in the evolution of early humans.

According to the head researcher and graduate student Rachel N. Carmody, human adoption of cooking methods may explain evolutionary increases in body and brain size, as well as human inclination toward high-energy activities such as long distance running.

Cooked diets are also easier to digest and may account for the smaller size of teeth and guts in humans today.

“The astonishing thing here is that cooking is the signature feature of the human diet compared to other animals, and yet these are the first experiments that show that, when you cook meat, you get more energy out of it,” said human and evolutionary biology professor Richard W. Wrangham, who also served as a member of the research team.

A long-standing hypothesis attributed evolutionary developments to increasing quantities of meat in ancestral diets. But the team’s research supports a complementary hypothesis, proposed almost a decade ago by Wrangham, that cooking allowed ancestral humans to extract more energy from the foods that they were already eating.

The study, which was launched in 2006 and conducted at Harvard’s Biological Research Infrastructure, used mice to test the energetic effects on body mass of cooking and pounding meat and sweet potatoes.

The mice were administered four different treatments of either sweet potatoes or meat—raw and whole, raw and pounded, cooked and whole, and cooked and pounded.

The results indicate that the energetic effects of cooking were greater in both foods than those of pounding, and that cooking further improved the energetic value of already-pounded food.

Hungry mice also strongly preferred cooked food, suggesting that the energetic effects of the cooked diet were obvious to the subjects themselves.

The research also suggests that biochemical methods currently used to determine the calorie values reported on food labels misestimate the energy value of poorly processed foods.

“Whether you eat raw food or cooked food is a personal choice,” said Wrangham. “What we’re really drawing attention to is the fact that you will get fewer calories out of food that is raw than food that is cooked. It’s time that we recognize that in our nutritional labeling.”

The team’s findings, published Monday in the Proceedings of the National Academy of Sciences, may have implications for scientists studying malnutrition and obesity worldwide.

According to Wrangham, the team hopes to continue its research to better understand the genetic differences between humans and other primates.

“I think this research really gets to the heart of why humans are the way we are,” said Carmody.

—Staff writer Akua Abu can be reached at aabu@college.harvard.edu.