12 A Healthy Body 12.1 How Do We Keep Our Bodies Healthy? 12.2 Food Substances 12.3 A Balanced Diet 12.4 Natural Food and Processed Food 12.5 Digestion and Absorption of Food 12.6 The Fate of the Digested Food 12.7 Our Circulatory System 12.8 Fatty Foods in Our Diet and Their Effects on Our Health 12.9 Exercise and Health 12.10 Need for Rest Summary Glossary Key Points Test yourself Index