Duchenne muscular dystrophy (DMD) is a severe progressive muscular dystrophy caused by mutations in the DMD gene, leading to the absence of a functional dystrophin protein. Besides muscle problems, metabolic, gastrointestinal (GI), and resulting nutritional issues contribute to the pathology. This aspect of the disease is often neglected. Assessment by a dietician should be part of routine check-ups. In early stages, overweight, caused in part by corticosteroid use, is common and, together with the primary deficit in dystrophin, affects muscle and whole body metabolism. In later stages patients are at risk of undernutrition, e.g. due to problems with swallowing and chewing. When the disease progresses, GI issues, including constipation, metabolic acidosis, gastroparesis, and reflux, are often seen. The precise role of nutrition and metabolic problems has not been well-studied. There is a need for natural history data, including dietary data, and good outcome measures regarding body composition, tailored to DMD patients. Furthermore, few well-designed studies, both preclinical and clinical, into the use of dietary supplements and on nutrient requirements have been performed. Good guidelines for maintaining a healthy weight and nutritional intake are currently lacking. Additionally, the risk/benefit ratio of high doses of over-the-counter supplements, their effect on different muscle types and potential interactions with other medicines require more detailed investigation. Families should be encouraged to speak with the clinical team and the pharmacist. The importance of fluid intake and dental hygiene should be stressed as well. Guidelines for diet and supplements need to take into account the stage of the disease and background culture, and be readily accessible in understandable formats, such as short videos and one-page explanations. It may also be helpful to provide examples of recipes and alternatives to make implementation of dietary change in daily life easier.