There may be five food groups (grain, fruits and vegetables, dairy, meat and fats, oils and sweets), but every food item is constituted by three important nutrients: carbohydrates, proteins and fats. Each one is transformed into usable energy, which is measured in calories. Those are, in fact, a unit of heat-energy. One calorie is the energy that is required to increase the temperature of one gram water by 1 degree Celsius. The calories people count actually are kilocalories (meaning thousand calories). So, one kilocalorie (kcal) is the energy that is required to increase the temperature of one kilogram of water by one degree Celsius. The quantity of energy that is provided by food products is mostly measured in kilocalories.

How many calories?

Each gram of carbohydrates delivers 4 kcal, as does each gram of protein. Each gram of fat, however, delivers more than twice that amount: 9 kcal. So, it seems logical to think that if you want to lose weight, you just have to stop eating fat, since it delivers a lot of calories. But in order for the human body to remain healthy, it requires carbohydrates, proteins and fats in the right amounts. A common guideline is that sixty percent of your daily caloric intake should come from carbohydrates, thirty percent from fats and ten percent from proteins.

The optimal amount of calories that should be consumed to maintain a healthy weight is based on the amount of energy that is needed while resting and the amount of energy that is used during the daily activities. This optimal amount of calories differs per sex, age, activity level and weight. To determine the number of calories that is needed to simply ‘exist’ one day, is called the basal metabolism. To determine this, you have to input your weight in kilograms, height in centimeters and age in years in the following equations, known as the Harris-Benedict formula:

Men: BMR (basic metabolic rate) = 66 + (13.7 x weight) + (5 x height) + (6.8 x age)
Women: BMR = 655 + (9.6 x weight) + (1.8 x height) + (4.7 x age)

However, keep in mind that these equations do not take in account your daily activity level and genetic predisposition.

So, if your body needs about 2000 calories per day, that means that those calories will provide you with enough energy to keep your metabolism going and allow you to function properly. If you consume more, those extra calories will be stored as fat tissue. If you consume less calories, you will lose about a pound of bodyweight for each 3500 calories you eat less.

Important!: If you consider losing weight in a healthy and durable way, consult a dietitian, nutritionist or physician first. Don’t just stop eating, your body needs nutrients to function properly!