Human Metabolism and Food Energy Production

Some say that the human body is no different from the bodies of other mammals, and in some senses, that is true. We all have hearts, stomachs, livers, etc., and our body chemistry is pretty much the same. If that were not true, we would be unable to eat meat or maintain a body temperature different from our environment. Still, despite these similarities, there are huge differences between human metabolism and the way we produce the food energy our bodies use.

For our body size, humans consume more calories each day than any other mammal. Evolutionists attempt to relate humans to chimps, gorillas, and orangutans, but the way humans handle food energy is radically different from the apes. When a baby human is born, its metabolism is very similar to an adult human, but it skyrockets over the first year of life. By the first birthday, toddlers burn over 50% more energy than we would expect for their size. Much of this consumption is to develop the brain. Throughout childhood, human metabolism will decline, reaching adult levels at around age 20, with boys declining more slowly than girls. After that, the energy expenditure is steady from age 20 until about age 60, and then it declines again.

Chimps, gorillas, and orangutans foraging for food can obtain between 200 and 300 k/cal each hour. At that rate, it takes apes about seven hours of foraging to get the k/cal they need for the day. Human metabolism requires more k/cal per day – around 2000 for women and 2500 for men, depending on body mass, activity, and age. Human hunter-gatherers can easily bring in 3000 to 5000 food k/cal per hour. Farmers produce much more than that. Until the middle 1800s, more than half of America’s workforce were farmers. Since humans have not had to spend so many hours obtaining food, we have time to devote ourselves to science, medicine, teaching, and the arts.

Human efficiency of food production allows children the freedom to grow and learn without spending every waking hour finding food. The problem we have involves food distribution and food waste. Our bodies are amazing machines of human metabolism. Herman Pontzer of the Duke Global Health Institute wrote, “The human body is a wonder of coordinated chaos. Every second of every day, each of your 37 trillion cells is hard at work, pulling in nutrients, building new proteins, and doing the myriad of other tasks that keep you alive.”

The human body is uniquely designed to serve others and serve God. That fact led the Psalmist to write, “I will praise you, God, for I am fearfully and wonderfully made. I know that full well” (Psalms 139:14). It also speaks to the value of human life and the importance of living as God has called us to live.

— John N. Clayton © 2023

Reference: “New Human Metabolism Research Upends Conventional Wisdom about How We Burn Calories” by Herman Pontzer in Scientific American magazine, January 2023.