The main reason why people with Crohn’s disease experience weight loss and malnutrition, which is considered a severe complication of the condition, is because the inflammation in their intestines makes digesting food and absorbing nutrients more difficult.
Severe diarrhea, another common symptom of the disease, can cause dehydration that leads to weight loss as well, meaning the body is depleted of fluids, nutrients, and electrolytes like sodium, potassium, magnesium, and zinc.
Other symptoms like abdominal pain and nausea can reduce one’s appetite, and frequent bowel movements can make people eat less to avoid the diarrhea that may follow.
Some medications used to treat Crohn’s disease have serious side effects. Corticosteroids, for example, can increase risks for type 2 diabetes and decrease healthy muscle mass, while the drugs sulfasalazine and methotrexate can prevent the body from absorbing folic acid, a vitamin that helps with cell growth.
People who have the condition often need to alter their diet to reduce the severity of their symptoms, but the types of foods they need to avoid vary from person to person. Lactose, spices, alcohol, and carbonated drinks are examples of foods and beverages that some people may need to avoid.
Crohn’s disease symptoms can start before the age of 15; however, most people are usually diagnosed between 20 and 30 years old. (About a quarter of people with the condition are diagnosed during childhood.)
Source: https://www.buzzfeed.com/katiecamero/tyre-nichols-crohns-disease