These measurements are based on100 grams of each food.
Different foods have different amounts of calories because the calories in the foods we eat actually come from the 3 macronutrients, fat, carbohydrates and protein.
1 gram of fat contains 9 calories
1 gram of carbohydrates contains 4 calories
1 gram of protein contains 4 calories
Each food contains a different amount or percentage of those macronutrients. Therefore foods containing a higher percentage of fat have more calories than foods that contain a higher percentage of protein and or carbohydrates. Below are the percentages of the macronutrients each food consists of.
Since the calories come from each macronutrient that the food consists of a simple way to find out roughly how many calories the food has is this equation below.
Multiply the grams of fat x 9 + the grams of carbohydrates x 4 + the grams of protein x 4.
For example here is the equation to find the calories in 100 grams of Avocado.
Macronutrients in 100 grams of Avocado:
Fat: 15 grams
Carbohydrates: 9 grams
Protein: 2 grams
15 x 9 + 9 x 4 + 2 x 4 =179
Overall the calories in food comes from the amount of fats, carbohydrates and protein that the food contains.
To find the macronutrients of other foods click here