Ancestral health

In a Paleolithic lifestyle (also known as paleo or primal lifestyle), one attempts to live as humans presumably did in the Paleolithic era (Old Stone Age), or to recreate such a lifestyle in the present day. The rationale for such an approach is that humans evolved to live in a Paleolithic environment. Therefore, their body and mind can be expected to be adequately adapted to the concomitant hunter-gatherer lifestyle. Agriculture, on the other hand, only appeared about 10 000 years ago at the beginning of the Neolithic era, and industrial society only about 200 years ago. Proponents of a Paleolithic lifestyle assert that insufficient time has passed for humans to adapt to the changes brought by farming and industrialization, leading to a mismatch between modern lifestyle and the human genome.

While a small number of cultures in the world continue to live a hunter-gatherer lifestyle, a subculture of people has emerged in Western societies who try to recreate elements of a Paleolithic lifestyle. Their motivation is to enhance health, fitness and happiness by avoiding the common "diseases of civilization", such as obesity, some cardiovascular diseases, metabolic syndrome, increasingly prevalent allergies, some forms of depression, and chronic stress. Supporters of the Paleolithic lifestyle say these diseases are not evidenced among hunter-gatherers, and therefore they are attributed to the modern, "civilized" lifestyle.

Compared with ancestral humans, modern humans often have increased body fat and substantially less lean muscle, which is a risk factor for insulin resistance. Human metabolic processes were evolved in the presence of physical activity–rest cycles, which regularly depleted skeletal muscles of their glycogen stores. To date, it is unclear whether these activity cycles universally included prolonged endurance activity (e.g., persistence hunting) and/or shorter, higher-intensity activity. It is estimated that ancestral humans spent one-third of their caloric intake on physical activity (1000 cal/day out of a total caloric intake of 3000 cal/day) and that the Paleolithic lifestyle was approximated by the WHO recommendation of a physical activity level of 1.75, or 60 minutes per day of moderate-intensity exercise.

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