If your New Year’s resolution involves losing weight or eating healthier, you should be reading the labels on everything you eat and drink. But what should you look for? And what do all the numbers mean?

Here’s everything you need to know.

Serving sizes.
All of the information related to the nutrients are based on the serving size indicated. So if you eat two servings, double the calories, fat, sodium, etc. Don’t just assume that there is one serving in every package.

Calories are a unit of measurement related to energy. When you consume more calories than you use, the excess is stored in your body, leading to weight gain. Only 20-30 percent of your calories should come from fat.

Contrary to their reputation, fats are actually important nutrients. However, not all fats are the same. Mono- or polyunsaturated fats are the best choices. Saturated fats should be eaten sparingly. And you should avoid trans fat.

Essential nutrients.
According to the FDA, most Americans don’t get enough dietary fiber, vitamin A, vitamin C, calcium, and iron in their diets. Foods that are high in these nutrients are good for your health.

Fats, cholesterol, and sodium.
Eating too much of these nutrients may increase your risk of certain chronic diseases, like heart disease, some cancers, or high blood pressure. Limit your intake to the recommended daily values listed at the bottom of the food label.

It’s important to look at the ingredients as well. Foods with less than half a gram of trans fat per serving can be listed as 0 trans fat. But if the ingredients contain the term “partially hydrogenated,” the food has trans fat. Added sugar can also go by other names, including high-fructose corn syrup, sucrose, maltose, dextrose, and maltodextrin, among others.