The Paleo Diet: The Rationale

The diet is based on several premises: 

• One of which is that human ancestors evolved for thousands of years and became well-adapted to foods of the Paleolithic era. 
• Advocates argue that food cultivation and preparation greatly declined in quality about 10,000 years ago, with the advent of agriculture and domestication of animals and that humans have not evolved to properly digest new foods such as grain, legumes, and dairy, much less the highly-processed and high-calorie processed foods that are so readily available and cheap.
• This has led to many of our modern-day problems such as obesity, heart disease, and diabetes.

Advocates claim that followers of the diet may enjoy a longer, healthier, more active life.

Human physiology has changed little since the time our ancestors were hunter-gathers. Modern humans are adapted to the diet or diets of the Paleolithic period. The dawn of agriculture and industrialization has led to the availability of foods for which we are not evolutionary adapted. It is possible to understand the ancient diet and reproduce it in modern times, and to learn from contemporary hunter-gatherers.

The Modern Day Paleolithic Diet 

No dairy food -- Very little cereal grains --Food was not salted -- Lean meat was eaten.

More Protein

Meat, seafood, and other animal products represent the staple foods of modern-day Paleo diets, since advocates claim protein comprises 19-35% of the calories in hunter-gatherer diets.The Centers for Disease Control and Prevention, the national public health institute of the United States, recommends that 10-35% of calories come from protein.

Fewer Carbohydrates

The diet recommends the consumption of non-starchy fresh fruits and vegetables to provide 35-45 % daily calories and be the main source of carbohydrates. According to the United States Department of Agriculture, the acceptable macronutrient distribution range for carbohydrates is 45 to 65 percent of total calories. A typical modern diet gets a lot of carbohydrates from dairy products and grains, but these are excluded in the Paleolithic diet.

Seeds such as walnuts are rich sources of protein and micronutrients.

High Fiber - High fiber intake not via grains, but via non-starchy vegetables and fruits.

More Fat - Advocates recommend, relative to modern diets, that the Paleolithic diet have moderate to higher fat intake dominated by monounsaturated and polyunsaturated fats and omega-3 fats, but avoiding trans fats, and omega-6 fats since saturated fats are considered to have little or no adverse effects upon cardiovascular disease risk.

Less Salt - It is well known that modern diets are high in salt and many diets, including the Paleolithic, recommend a reduction.

Balanced Alkaline vs. Acid

Any food presents either a net acid (e.g. meats, fish, grains, legumes, cheese, and salt) or alkaline (e.g. fruits and vegetables) load to the kidneys.A good diet strikes a balance.

More Micronutrients

A higher intake of vitamins and minerals is recommended via grass-fed meats, fruits, and vegetables rather than grains.

Energy Density

The Paleolithic diet has lower energy density than the typical diet consumed by modern humans.This is especially true in primarily plant-based/vegetarian versions of the diet, but it still holds if substantial amounts of meat are included. For example, most fruits and berries contain 0.4–0.8 calories per gram, and vegetables can be even lower than that (cucumbers contain only 0.16 calories per gram). Game meat, such as cooked wild rabbit, is more energy-dense (up to 1.7 calories per gram), but it does not constitute the bulk of the diet by mass or volume at the recommended plant/animal ratios, and it does not reach the caloric densities of many processed foods commonly consumed by modern humans: most McDonald's sandwiches such as the Big Mac average 9 calories per gram, since there is a high fat content and fat yields 9 cal/gram. and sweets such as cookies and chocolate bars commonly exceed 4 calories per gram.

Diets with a low caloric density tend to provide a greater feeling of satiety at the same energy intake, and they have been shown effective at achieving weight loss in overweight individuals without explicit caloric restrictions.

Even some authors who may appear otherwise critical of the Paleolithic diet have argued that the high energy density of modern diets, as compared to ancestral or primate diets, contributes to the incidence of diseases of affluence in the industrial world.