The Paleo diet is a nutritional plan based on foods that are similar to what might have been eaten during the Paleolithic era. A paleo diet generally includes lean meat, fish, fruits, vegetables, nuts, and seeds that could be obtained through hunting and gathering in the past. A paleo diet restricts the foods that became common with the introduction of agriculture about 10,000 years ago. These foods include dairy products, legumes, cereals, and grains.