Humans in relation to Animals

Reduced physical levels has often been cited as one of the main factors of obesity in developed nations. However, it has yet to be ascertained just how sedentary peoples lifestyles have become.

Dr. Steven Heymsfield, deputy director of the Obesity Research Center at St. Luke's-Roosevelt Hospital in New York compiled data from many previous studies that assessed the energy expenditure of people as well as a variety of wild mammals, including orangutans, wolves, wildcats, bats, jack rabbits, squirrels and mice.

The main objective of the study was to find out the levels of physical activity before humans were domesticated. This is based on the assumption that wild animals would have physical activity levels similar to primitive humans.

The findings revealed that people living in developed countries are much less active as compared to primitive humans, who had to forage and hunt, as well as to fend off predators. In the case of wild animals, the ratio of calories burnt at rest as compared to those burnt in physical activity ranges from 1:1 to 1:2. The typical urban human calorie expenditure in comparison is only 1:1/2. This is half or less than half of the calories that we used to burn in the past!

However, the study also revealed that among certain groups of people, specifically army recruits and athletes, burn almost as much energy per day as with animals. This is the level of physical activity that is probably more in line with those of primitive humans.

American Society for Clinical Nutrition San Diego, CA February 24, 2002.