## How does the weight of food change? Various factors can influence the final volume and weight of food when it is cooked. - Water absorption: Foods such as buckwheat, rice, and pasta swell during the cooking process, lowering the caloric content of the finished product. - Water loss: Protein products (meat, eggs, fish, etc.) change texture during cooking. When exposed to heat, eggs begin to curdle, and the muscle fibers in meat and fish denature, decreasing their weight. - Additional ingredients: Leavening agents used in cooking, such as yeast, increase the content of carbon dioxide, which lingers in the dough during baking. Its volume increases accordingly. - Cooking time: Prolonged heating reduces food's moisture content (and weight). - Added cooking fat: Cooking with fat increases the caloric content of food (1 g of fat contains 9 kcal). Fat is easily absorbed by food and significantly increases its weight during cooking. - Vegetables and fruits (except starch-containing fruits): These decrease in volume, which decreases the calorie count. > Vegetables should be cooked gently because the glycemic index increases when vegetable fibers are broken down. It is recommended that vegetables be heated to 140–158 °F, or they can be cooked in a steamer to 176–194 °F within five minutes. In boiling water, cook for no more than three minutes. > Legumes absorb water and significantly increase in size, while the caloric value per 100 grams of the cooked product decreases. > Dairy products usually do not have weight changes when heated, but their calories increase. ## How is calorie content affected by different cooking methods? Cooking is the main factor that determines the caloric content of dishes. - Cooking in boiling water reduces calories by almost 20 %, as excess fat, sugar, and protein are lost. But there are exceptions, such as starchy vegetables like potatoes, carrots, and beets. When boiled, their calorie content increases by about 30 % as the starch is modified and gives additional calories. - Grilling and baking are also healthy ways to cook meat, as grilling drains fat and reduces calorie content. - Frying in oil increases the calorie content of the dish. However, frying food in a dry pan can decrease the product's calorie content. - Stewing is similar to boiling‒only the calories do not go into the broth but into the gravy. - Steaming is the most useful method as it reduces calories and preserves vitamins. ## From theory to practice Let's see how the nutritional value of common foods changes. | Product | Raw product (100 g / calorie) | Cooked (100 g / calorie) | |----------------|-----------------------------|------------------------------------------------| | Potatoes | 58 | ~ 180 fried <br> ~ 150 fried <br> ~ 140 baked <br> ~ 110 boiled | | Buckwheat | 305 | ~ 100 boiled | | Chicken breast | 113 | ~ 95 boiled <br> ~ 100 grilled <br> ~ 230 fried | | Beef | 187 | ~ 254 boiled <br> ~ 232 stewed <br> ~ 175 baked | | Salmon | 150 | ~ 185 boiled <br> ~ 190 steamed <br> ~ 200 grilled <br> ~ 270 lightly salted | | Pasta | 350 | ~ 175 boiled | | Chickpeas | 390 | ~ 195 boiled | | White rice | 344 | ~ 116 boiled > Boiled egg has almost no calorie change and may only increase slightly with prolonged cooking.