Barley may be lower on the glycemic index than wheat, but it’s still very high in carbohydrates, and it’s also a grain that contains gluten.
Grains as Processed Food
Arguably the first step to living a Paleo lifestyle is to rid all processed food from your diet, and you’d be hard pressed to come across any grains in the grocery store that have not been processed. Making them edible requires a fair amount of human intervention, and the payoff isn’t worth it because they aren’t even that nutritious. They have small amounts of vitamins and minerals, but you can get a much higher serving of these nutrients from meat, eggs, fruits and vegetables without feeling hungry two hours later.
Why We Should Avoid Gluten
To make matters worse, gluten is a serious anti-nutrient. It sticks to the insides of our guts, which are designed to be permeable to let some nutrients into the blood stream. When gluten blocks these nutrients from getting through, the gut responds by increasing its permeability. That way the nutrients can get through, but so can toxins and undigested foods. The body responds by rushing white blood cells to the area to fight off the foreign substances. This immune response also involves inflammation, which is why people who consume gluten on a regular basis tend to have chronic inflammation. Most of us living a Paleo lifestyle try to avoid chronic inflammation because it is a dangerous precursor to all sorts of illnesses, including diabetes and heart disease.
For more reasons to avoid grains, check out this post by Mark Sisson.