A calorie is a unit of energy, and can come from a variety of different sources. How many calories you consume in a day determines how much energy you provide for your body. If you consume too many calories on a daily basis, you can gain weight as the energy is converted to fat. If you eat fewer calories than your body needs, you can burn fat and lose weight.  Ingredients that are calorie-dense, like butter, oil, or sugar, tend to be bad for you. Foods that tend to have a low caloric content are usually good for you, like avocado, celery, or corn. Empty calories refer to calories that are low in nutritional value, like pizza, soda, or sausage. The next row on the label is fat, and it is accompanied by 2 different types of fat underneath the total number content. Fat helps provide cell development and stores energy in the body. It is found in a lot of plants and animals, and isn't necessarily bad for you if you don't have too much of it.  Saturated fat refers to fats that come from animals. They are worse for your body than unsaturated fats. Trans fats are a kind of unsaturated fat found in oils. They are especially bad for you, and you should avoid foods with a lot of trans fat in them at all costs. Cholesterol is a fat-like material that occurs naturally in your body. You need some forms of cholesterol to regulate hormones, but too much cholesterol can increase your risk for heart disease. Avoid foods with high cholesterol values whenever you can to keep your heart happy and healthy.  There are 3 main types of cholesterol: HDL, LDL, and VLDL. They refer to the density of the cholesterol. Your body needs some HDL to keep your liver healthy, but LDL and VLDL should be avoided. Red meats and junk foods tend to be high in cholesterol. Under cholesterol, you can find the sodium content in a single serving. Sodium is found in salt, and your body needs less than 500 milligrams a day. Too much sodium can cause your blood pressure to rise, which can increase your risk of stroke, heart failure, osteoporosis, and cancer. Stay away from foods that are high in sodium whenever you can.  If you're trying to cut down on sodium, consider cutting soda and junk food out of your diet completely. Try to consume less than 20% of your daily value in sodium every day. Carbohydrates are nutrients that produce calories. They generate fuel for the nervous system and muscles, and help your body metabolize fats. Carbohydrates can be bad for you if they come from a source that is high in fat, sodium, or cholesterol (such as some pasta dishes, pizza, or dairy products).  Eating too many carbohydrates can put you at risk of weight gain and type 2 diabetes. Not eating enough carbohydrates can result in hypoglycemia or energy loss. Fiber is a nutrient found in fruits, vegetables, grains, and legumes. Fiber helps your digestive tract and aids in the burning of fat. Eating fiber is a good way to promote a healthy diet, and foods that tend to be high in fiber are usually very good for you. Aim to consume at least 20-30 grams of fiber every day.  Fiber can also counteract high cholesterol levels if you consume enough of it on a daily basis. There are fiber supplements that you can take to artificially raise your fiber intake every day. There are 2 types of sugar, natural and added sugar. Natural sugars are found in fruit and dairy products and aren't bad for you in small amounts. Added sugars are harder for your body to digest, and should be avoided whenever possible. Natural sugars usually come in foods that are high in fiber or protein, while added sugars are can lead to weight gain, heart problems, or type 2 diabetes. Added sugars are only listed on some food labels. To make sure that there are no added sugars, look for the phrase “sugar free” printed on a container or check for corn sweetener, high-fructose corn syrup, or sugar in the ingredients list. Protein is a nutrient that promotes muscle growth and health. It is often found in meat, but also appears naturally in nuts, legumes, and eggs. Protein also helps the immune system and aids your body's metabolism. Don't focus exclusively on a food's protein content though, since a lot of high-protein foods often come alongside high fat, sodium, or cholesterol contents.  Try to get protein in foods that are also low in carbohydrates or calories. Seafood, vegetables, and lean meats are all excellent sources of protein. You can increase your daily protein intake by mixing protein powder into shakes if you want to get enough protein without increasing the amount that you're eating every day. Under the protein or fiber, you'll see a black bar separating another set of ingredients. These are vitamins, minerals, and nutrients that are found in the food. The most common inclusions are vitamin A, vitamin C, calcium, and iron. These nutrients are good for you, and if the list under this black bar is longer, then the food is probably healthy for you.  Vitamin A helps promote vision and keeps your immune and reproductive systems operating at a healthy level. It also helps your lungs, kidneys, and other organs functioning normally.  Vitamin C helps repair body tissue and promotes healthy skin.  Calcium keeps your bones healthy and strong. It also helps blood clot and makes it easier for muscles to contract. Calcium consumption is important when you're young.  Iron transports oxygen in your blood and helps to convert nutrients into energy. If you're iron deficient, you could become anemic.
Note how many calories are in each serving. Read the fat content in a serving and check what types of fat are present. See how much cholesterol each serving has. Check the sodium content of the food. Look at the total carbohydrates contained in each serving. Check how much fiber you can get from a serving. Read the sugar content and check for added sugars. Note how much protein is in each serving. Check the vitamins and additional nutrients listed at the bottom.