The Paleolithic period predates the process of cooking. This removes many of the foods found in the common diet from consideration. Raw grains are inedible until processed and cooked. This eliminates bread and pasta products from the Paleolithic diet. Other foods with similar concerns are beans and potatoes.
Foods that require processing not available to the Stone Age man are also prohibited. This includes dairy products and sugar.
Many proponents of the Paleolithic diet suggest consuming low-fat meats. While the Stone Age hunter-gatherer--if he was a successful hunter--consumed meat, the wild meat was much lower in fat content than the farm-raised meats found in grocery stores.
Soft drinks obviously weren't available millions of years ago. Beverage choices are limited to water and teas made with allowed plant leaves. Some versions of the Paleolithic diet do allow for the occasional consumption of beer or wine.
Candy also is prohibited.