The Paleo Diet is naturally low in calories and carbohydrates. This diet encourages high intake of red meats and animal proteins, and the elimination of dairy, grains, legumes, and many fruits. The primary difference between the paleo diet and other healthy diets is the absence of whole grains and legumes, which are good sources of fiber, vitamins and other nutrients. Dairy products are also off limits, and they are good sources of protein and calcium. While it may help with weight loss but may cause fatigue, headache, constipation, mood swings and increased risk of heart disease.