Ketone bodies are molecules that are water-soluble and provide nutrients to cells when glucose is not readily available . This metabolic by-product has been demonstrated to boost immunity and fight off invading pathogens and disease . The study suggests that fasting or intermittent fasting is healthy for people due to ketone body production for immune cells . T cells are one of the main cell types affected by this nutrient source, it demonstrates how different nutrients can be optimal for different cell type and help an individual build a stronger immune system .