The gluten-free diet is used to treat celiac disease and gluten intolerance. Celiac disease is diagnosed through endoscopic and lab testing, gluten intolerance/gluten sensitivity is more common than celiac disease, but is less understood.
To date, scientific data does not support the gluten-free diet as advantageous to athletic performance in the person without celiac disease; support for this diet for athletes is testimonial, not evidence-based. Some athletes have reported less GI discomfort and fatigue when following the gluten-free diet. It is possible to meet the demands of training and competing while following a gluten-free diet, but it requires attention to food choices. Care must be taken to consume adequate carbohydrates and calories; additionally, many gluten-free foods are not fortified with B vitamins and iron, and those not made with whole grains may be lower in fiber. What the gluten-free diet may do is make the athlete more aware of what works to combat digestive issues, and allow greater inclusion of less-processed, whole foods in the diet. Keep in mind that just because a food is gluten-free does not mean it is automatically healthy – a gluten-free donut is still high in calories and low in nutrients!