Study data show the more people adhere to a gluten-free diet, the more likely they are to gain weight, which registered dietitian Amy Jones says may be linked to better absorption of nutrients and calories. RD Rachel Begun says another factor is the availability of processed gluten-free foods that can be high in calories, fat and sugar. Jones and Begun say it is important to prepare patients on a gluten-free diet for possible weight gain and encourage them to eat whole foods that are high in nutrients.