Never heard of "insuluble." If you mean "insoluble", it means a substance that can't be dissolved within another substance. For example, sand is insoluble in water.
insuluble NSP binds water in the large intestine to add bulk to faeces and so stimulates the lining of the intestinal wall, stimulating peristalisis which aids the speedy removal of this waste from the body - i.e. preventing constipation.
because increase in molecular werght increases the hydrophobic part and decreasesv the hydrophilic part which is soluble. therefore increase in insuluble part decreases the solubility.
Fats are chemically breaking down into fatty acids and glycerol by lipase in the small intestine . Unlike amino acids , glucose and glycerol , fatty acids are insuluble in water . However , they form colloidal particle with the bile salts which can easily dissolved into the membrane of the epithelial cells and enter the calls . Once inside the cells , the particles are coated with proteins . These fat particles now are too big to diffuse into the blood capillaries . However , they can easily move through the openings leading to the lymph capillaries which is the lateals . The lymph vessel contain a fluid called lymph which is derived from tissue fluid . Fat particles mix with lymph to form a milky fluid call chyle . Chyle is eventually discharged to all parts of the body , especially to the liver .