Burn is a book about the engine in our bodies, metabolism. Its how we turn food in to work and despite that mathematic expression, how there’s so much more that goes into how we take in energy and how we expend it. Dr. Herman Pontzer is a anthropologist, taught under the famed Harvard anthropologist Daniel Lieberman known for his exclamation that mankind was built to run. Pontzer’s topic summarizes that today’s novel dietary health problems of diabetes, obesity heart disease and such are not and can never be cured by fad diets and exercise.

He takes a similar approach to Liebermann in using a pre-modern society, in this case the hunter gatherer society called the Hadza in Eastern Africa, to compare their health with our evolutionary ancestors and that of those who lived in the developed world. His argument unfolds by first exposing on how evolution is an imperfect chain reaction that constantly tests and retests adaptations until in the end, the best species reproduce and carry on their genes. Some of these adaptations can be traced to ancestral species and others are prone to faults still. He then goes into a basic expose of college level biology in how respiration and photosynthesis came about, the absorption and creation of the mitochondria, the Krebs cycle and much more through diagrams you’d find in a textbook.

In the following chapters, the BMR, the basal metabolic rate, is recorded via double water methods to track how we expend energy through different activities and how our body for the most part, invests most of its energy in the normal upkeep of our cells. In fact, one if the bigger claims Pontzer makes is that, all of us expend energy in a small range, whether we are senditary couch potatoes or ultramarathoners. This range of 2000-3000 kcal (the proper measurement for energy as the Calories we see in the grocery store are 1,000 calories). The difference between the two and Hanza is in the amount of filling and fibrous foods we eat and how our bodies adapt to energy expenditures. This means that if one runs 5 miles a day but has the same height, sex and weight as someone who doesn’t run, they could both take in the same amount of food but the runner will divert more to muscle recovery and the other will divert more to other necessary functions. That being said running and exercise are not the silver bullet to weight loss, merely good health as our bodies can adapt back to their original weight if we are not diligent. Another expose Pontzer does is in how we differ from our primate relatives who can be just as lazy as us but pack leaner profiles naturally as their bodies adapted to less brain use and more physical power.

Pontzer’s final claims are in how our modern society is spending more energy to produce less food energy with less fiber. Its wrecking our environment and leading to unhealthy diet trends, especially when its cheaper financially then healthier less energy intensive foods. Pontzer advocates like most doctors for a balanced diet and regular moderate exercise as that’s what reduces stress and best distributes the food we take in. His findings are strengthened in his use of scientific charts and references to studies both fir and against his claims. His one weakness may be in using dad humor to break the fourth wall but it slides when his argument is taken in whole.