What is a critical weight in ALS?

Weight loss of 10% of the initial weight is considered significant. It is associated with increased risks of medical complications and of undergoing surgery (e.g., percutaneous endoscopic gastrostomy, PEG). Therefore, efforts should be made to maintain a stable weight through dietary changes and the use of high-calorie supplemental nutrition.

The prognosis for ALS is also determined by changes in body weight. A decrease in weight to a body mass index (BMI) below 18.5 kg/m² (mildly underweight) is associated with a poor prognosis (compared to ALS patients of normal weight or who are overweight). This situation calls for a change in thinking. While in internal medicine (particularly to prevent cardiovascular diseases) a body weight as low as possible is desirable, in ALS a higher body weight is prognostically advantageous. The positive impact of a higher body weight is likely due to the fact that ALS can be associated with malnutrition (due to swallowing difficulties) or increased energy requirements (due to respiratory dysfunction or increased resting energy expenditure).