Why must foods be changed from complex to simple molecules?

Foods must be changed from complex to simple molecules to facilitate digestion and nutrient absorption in the body. Complex molecules, such as carbohydrates and proteins, are often too large to be absorbed directly through the intestinal wall. Enzymatic breakdown transforms these complex substances into simpler forms, like glucose and amino acids, which can then be easily absorbed into the bloodstream and utilized for energy, growth, and repair. This process ensures that the body can efficiently utilize the nutrients present in food.