People with gluten allergies often suffer from gastrointestinal problems, malabsorption of vitamins and minerals, and problems managing their weight. While gluten allergies are more commonly associated with weight loss, especially in children, some people gain weight as a result of these allergies. Celiac disease is one of the most common forms of gluten allergies. Current research shows how obesity and weight gain can be a symptom of a gluten allergy, and can also be the body's response to a sudden change to a gluten-free diet.

While many people and doctors put unexplained weight gain and digestive problems down to poor eating habits, few realize that people struggling to manage and lose excessive weight may actually have an allergy to gluten. Some experts explain this weight gain as the body going into survival mode. People with gluten allergies, and especially those with celiac disease, have problems processing and absorbing food, vitamins and minerals. To cope with this malnourishment, the body stores fat to use later.

In addition, celiac disease is an autoimmune condition that is known to affect the thyroid gland. The thyroid uses iodine to make and secrete hormones that control the body's metabolic rate. People with celiac disease struggle to absorb minerals like iodine, damaging or compromising the thyroid gland. When this happens, the thyroid produces 5-monodeiodinase, which is a chemical that causes the body to conserve and store fuel.

Research has shown that switching to a gluten-free diet can also cause weight gain (or loss). One explanation is that as the intestines heal, the body begins absorbing more nutrients and calories. Likewise, gluten-free substitutes may also have more calories per serving. Finally, people with gluten allergies often suffer from cravings, leading to larger meal size. In such cases, these individuals may need to downsize their gluten-free portions now that these cravings have subsided and their bodies are healing.