Question: I'm really confused about calories and fat. I watch what I eat but don't really know what to look for! Should I be counting calories or fat grams? Or percentages of calories from fat? What are calories and fat anyways?
Answer: A calorie is the standard unit for measuring energy released from energy-yielding nutrients, such as fat, protein, and carbohydrate. Fat is an essential nutrient that helps the body transport and absorb fat-soluble vitamins (e.g., A, D, E, and K), among other functions. Whereas proteins and carbohydrates have only four calories of energy per gram, fat has nine. Food labels are now Federally standardized to help make it easier for the consumer to know what's in a particular food. You can calculate the percentage of calories from fat by looking at the column marked "Percent Daily Value" for total fat and simply add up these percentages. It's recommended that fat make up no more than 30 percent of your daily diet (meaning less than or equal to 30 percent of total calories a day from fat).
Although it is important to watch both calories and fat grams, your focus needs to be on the total number of calories consumed, which often seems to be forgotten. With the introduction of low-fat and fat-free versions of many common foods, you'd expect people to lose weight. Instead, many are either staying at the same weight or even gaining weight. Sometimes you can eat more of these foods than their full-fat versions for the same number of calories. However sometimes low-fat foods contain more sugar than their full-fat cousins, and hence as many calories per serving. Ultimately, if you eat more calories than your body expends, regardless of whether these calories come from fat, protein, or carbohydrates, you will gain weight. Unused energy is converted and stored as excess body fat.