The significance of nutritional strategies in patients with inflammatory bowel disease in the context of malnutrition and the development of malnourished obesity

Inflammatory bowel diseases (IBD), including Crohn's disease and ulcerative colitis, despite the increasing incidence, still do not have a specific etiology. Diet seems to be an important factor, modifying the occurrence of the disease and its course. Diet can affect the symptoms of IBD both directly, e.g., by alleviating diarrhea, bloating and constipation, and indirectly by shaping the microbiota. Bacterial metabolites produced under the influence of supplied nutrients may contribute to the modulation of pro- and anti-inflammatory pathways, depending on the diet used. So far, IBD has been associated with weight loss and malnutrition. In recent years, a trend of sarcopenic obesity with concomitant malnutrition has been observed. The new phenomenon is called malnubesity. This work aims to review the most commonly used diets in IBD in order to evaluate them in terms of alleviating ailments, but also maintaining proper nutritional status and lack of obesity. Low-fiber, low FODMAPs, Mediterranean diet and Crohn's Disease Exclusion Diet diet were considered. We assume that diet is modifiable factor that is related to nutritional status and healthy body weight. In addition, the current knowledge on the relationship between nutrition strategies, obesity and IBD will be demonstrated.