By David Raubenheimer and Stephen J. Simpson
The two entomologists describe a fascinating, 30-year research journey, that took them from studying insect nutrition to postulating the cause of the human obesity epidemic. Along the way, they performed experiments as well as observations in the wild, progressing from insects to primates (including humans). The book is easy and entertaining. I recommend it.
The authors invented a concept which they named Nutritional Geometry. They concluded that many species, including humans, have more than one appetite. In humans they count five: Protein, Carbohydrates (CH), Fat, Salt, and Calcium. Each appetite regulate the food intake to meet a natural target, and thus achieve a healthy balanced diet.
They discovered that in many species, the dominant appetite is the one for protein. They named this effect Protein Leverage. If balanced food is available, the animal will eat a balanced diet. However, when the only available food sources are low in protein (and therefore high in CH or fat), the animal will eat more food, until it reaches its protein target. This results in consuming more energy than necessary, and consequently becoming fat. Conversely, if the food sources are too rich in protein, in order to hit the target, the animal will eat less, and loose weight. The fiber content of fruits and vegetables is the one ingredient that limits the amount of CH and fat that the animal can consumes. Fiber physically fills the stomach till no more can be ingested. Humans clearly exhibit the protein leverage phenomenon.
Obesity Epidemic Thesis
- The blame lies with ultra processed food (UPF), and its manufacturers
- The average target level for human protein consumption is 15% of total energy intake. Since the 1970s, humans consumed a few percent less than this target.
- Protein leverage predicts that we eat more CH and fats to compensate. The consumption data fits the prediction, and accounts for the increase in obesity.
- When protein leverage causes hunger and a need for more food we turn to UPF. UPF is designed to be commercially successful, not to make us healthy. As such it has the following characteristics:
- Engineered to be super tasty, it includes salt, fat, sugar, and many gruesome-sounding industrial ingredients.
- Low in protein. Forces us to eat more.
- Low in fiber. Allows us to eat a more.
- Low cost (protein is expensive)
- Long shelf life. (Fiber reduces shelf life).
- UPF manufacturers follow the tobacco industry in confusing the public regarding the effects of their products.
Eat enough protein. Your appetite will tell you when to stop. As for the rest, the book recommendations fit a Michael Polan quote which I love:
- Eat FOOD (not industrial products)
- Not too much
- Mainly fruits and vegetables.
Although the average target for protein is 15%, this number increases as we age. Over the age of 65 the recommended target is 20%.
An aside. The authors must have intercepted my emails. They cite "The three pillars of health" as:
- Sleep
- Exercise
- Nutrition
- Mice eating low protein foods became fat, but lived longer. (Especially if the extra energy came from CH not fat)
- Mice feeding on high protein food, stayed slim, had better reproductive capabilities, but lived shorter lives.
