The members of the nutrition committees at the big nonprofits seem to be convinced that human beings need to eat foods from all four of the Basic Four Food Groups.
In contrast, wild gorillas eat only vegetables and some fruit. But if a wild gorilla entered the weightlifting competition at the Olympics, it would win by a huge margin. It would win despite having eaten practically nothing from the meat group, nothing from the dairy group, and nothing from the grain group.
That’s because gorillas don’t hunt; they don’t fish; they don’t raise cows or chickens; and they don’t plant corn, wheat, or rice.
The vegetables and fruit that a gorilla eats provide enough of all but two of the nutrients that are essential in human (and gorilla) nutrition. The exceptions are vitamin B12, which comes from bacteria, and vitamin D, which comes from sunshine.
All animals can be classified into one of three main groups, according to what they are designed to eat.
Carnivores (meat-eaters) are built to catch and kill other animals and to eat and digest animal tissue.
Herbivores (plant-eaters) are built to eat and digest plant tissue.
Omnivores (everything-eaters), such as bears, are mainly built to capture and eat other animals.
However, they also have adaptations that allow them to get a lot of their nutrition from plant sources.
The herbivores can also be classified into several different groups, depending on the type of plants or plant tissue that they are built to eat.
Folivores are animals that mainly eat leaves. Frugivores mainly eat fruit. Browsers mainly eat shrubbery. Grazers mainly eat grasses. Gorillas are folivores.
A wild silverback male gorilla may eat about 60 pounds of salad per day, without dressing. Gorillas happily spend many hours a day chewing and swallowing leafy green vegetables.
However, human beings are simply not built to eat a gorilla-style diet. Our jaws are not strong enough, and our stomachs are too small.
If you tried to eat a wild gorilla’s diet, you too would have to spend too many hours a day simply chewing and swallowing.
It would be hard to chew and swallow enough food to get enough calories. You would lose too much weight, and you would be unhappy. That is why people cannot stick to a diet of nothing but “rabbit food” for very long.
Even people who try to eat a wild chimpanzee’s diet of leaves and fruit end up putting a lot of their food in a blender, which does the work of chewing for them.
They also tend to rely heavily on dried fruits and nuts, which are concentrated sources of sugar and fat. However, a diet of smoothies, raisins, and nuts is unnatural. Apes don’t have blenders. Nuts are high in calories, but they are not available year-round.
Dried fruits do not occur in the rain forests where apes live. Thus, no wild apes and no human societies have ever based their diet heavily on smoothies, nuts, and dried fruit.
Although a gorilla would outcompete human beings in weightlifting, human beings would beat them in the marathon.
Human beings are among the world’s elite long-distance runners. In fact, human beings are the only creatures that run long distances voluntarily, for fun. Human beings are also much smarter than gorillas, thanks to our abnormally large brains. To feed our enormous brains, we need a lot of glucose.
The most reliable natural source of glucose is the starch in the roots and tubers of many plants. Cereal grains, which are the seeds of members of the grass family, also contain lots of starch.
Unfortunately, these starchy foods are hard to eat, and the starch is hard to digest. In a potato or a grain of rice, many of the starch molecules are stored in the form of hard, nonreactive crystals.
Within these crystals, the starch molecules are held together by hydrogen bonds. If you bake a potato or boil rice, the heat and water will break those hydrogen bonds.
Then, water molecules attach to the hydrogen bonding sites. As a result, the starchy material swells and softens. Because of this process, called gelatinization, baked or boiled starches are much softer and easier to digest.
Of course, even a gelatinized starch is still a starch. Before that starch molecule can be used as a source of energy, the body must break it down into separate molecules of glucose. To convert starch to glucose, you need an enzyme called amylase.
Apes have only two copies of the gene that provides the recipe for amylase: one copy from each of their parents. In contrast, human beings have a few extra copies of the amylase gene.
As a result, human beings are better at digesting starches than apes are. These extra copies of the amylase gene are clearly a genetic adaptation to a starchy diet.
All of the populations of slim, healthy people throughout history have obtained the bulk of their calories from starchy staples, such as rice, wheat, corn, or potatoes.
The populations that eat a starchy diet have low rates of obesity and other chronic degenerative diseases.
Unrefined starchy foods, along with vegetables and fruit, truly are health foods. Many people are shocked to hear that they would be better off eating conventionally grown grains and produce, including plenty of “carbs,” than eating organic grassfed beef and dairy products.
Like most people in the United States, I was taught that children need to eat foods from the meat group (meat, eggs, and fish) and the dairy group (milk, cheese, yogurt, and butter) in order to grow up big and strong.
I was encouraged to believe that human adults need to continue eating meat and dairy foods to maintain good health and athletic performance.
So when I started reading nutrition textbooks, I was relieved to discover that vegetarians (people who don’t eat meat) and even vegans (people who refuse to consume any animal-source products) are not at risk for a deficiency of protein, calcium, or iron.
Rather, the scientific studies showed that eating even small amounts of foods that come from animals poses an unnecessary risk to human health.
Many people decide to become vegetarian or vegan because of how they feel about animals. For them, the question about whether to eat meat or wear fur or leather is a moral question.
However, I did not write this book to talk about moral questions. In this book, I deal with the scientific questions about how your food choices are likely to affect your health. If a plant-based diet posed health risks to human beings, I would explain those risks in detail and would describe how to minimize that risk.
Fortunately, the plantbased diet that many people have been promoting because of concerns about animal welfare or the environment also happens to be the diet that is best for human health.
My point is that you do not need to sacrifice your health in order to protect animals and save the environment.
On the other hand, if you switch to a plant-based diet to improve your own health, you will also spare the lives of animals and cause less damage to the environment.
Although the health-optimizing diet for a human being consists of plant-based foods, I try to avoid calling
it a vegetarian or vegan diet.
Many people who call themselves vegetarian eat a lot of dairy foods and eggs, or even a lot of fish. (A fish is an animal, not a vegetable!) Also, many vegetarians and even many vegans are eating far too much fat (especially too much omega-6 fat in the form of seeds and vegetable oils) and drinking too much alcohol. Bourbon and potato chips are vegan, but they aren’t health food!
The rules of thumb that I listed above (e.g., eat plants, not animals) are general rules that apply to the average person. However, there are a few people who need custom-tailored advice from a trained professional.
For example, people with some hereditary metabolic diseases, such as phenylketonuria, need special diets. People with fructose malabsorption may get diarrhea if they eat too many apples or pears.
People with celiac disease need to avoid wheat, rye, and barley. If you need a special diet for health reasons, you should talk to a registered dietitian.
Note that even a sudden change to a healthy diet can cause problems. If you have any serious health problem or are taking prescription medications, you need to talk to your doctor, nurse practitioner, or physician assistant before you make a major change in diet.
A sudden switch to a healthy diet can cause rapid improvements in circulation and insulin sensitivity.
As a result, people may need to stop taking some of their blood pressure medication. Diabetics may also need adjustments in their diabetes medications.
If you correct your diet without allowing your doctor to adjust your prescription medications, you could pass out from low blood pressure. You could even end up in the hospital or dead from low blood sugar!