Knowing the number of calories you should consume per day is vital to control your weight. If you neglect this aspect you will find surprises the next time you go to the scale.
We continually see on TVs and in the multitude of Internet ads those miracle diets that promise extreme weight loss or become a few weeks the next Rocky Balboa. The truth is that it is not necessary to look for diets with fancy names to achieve the desired results, simply suffice to have 2 pillars in mind when talking about food, calories consumed and macronutrients. In this article, I want to focus solely on how many calories to consume per day since it is the key to maintaining or modifying your weight.
How to calculate the energy needs of your body
Calculating the calories you need is done based on metabolic expenditure. Here we should make a distinction between basal metabolism and total energy requirement. Basal metabolism is the energy needs you require to perform basic functions of the body at rest and fasting. As you will do more things to be lying down without moving, to this number you have to make a series of modifications depending on different variables such as physical activity, which will get the total calorie requirement.
The basal metabolism is calculated in kilocalories/day and can be known by a test called indirect calorimetry. But also we can approach that number using different mathematic formulas that we shall see. The important thing is that once you know the number of calories you need you can make changes in your weight.
If you give your body exactly the calories it needs, you will maintain our weight. If there is a negative balance between what you ingest and what you spent, this leads to a loss of weight, while a positive balance leads to a rise in weight. Depending on the physical activity performed and the macronutrients (carbohydrates, fats, and proteins) ingested, that results in a greater change in the fat percentage of the body or in the musculature.
Different variables that affect basal metabolism
– Height and weight: the basal metabolism is lower in the short and lean people, while it is higher in tall and burly ones. A person with greater muscle mass will consume more calories, since maintaining that mass costs energy.
– Age: needs decrease with age, this is due to body composition throughout life, lean mass is being replaced by fat mass that needs less energy input for maintenance.
– Gender: it is usually higher in males, so we have commented before lean mass.
– Climate: it is higher in cold climates.
-Special situations such as high fever, stress, surgery …
Different formulas for calculating (approximately) the energy needs
Harris-Benedict formula: it is one of the most used, but does not take into account the fat percentage of the individual, so the more overweight the person, the greater the margin of error.
Katch-McArdle formula: if we have a bioimpedance scale is the one we should use since this formula does take into account lean body mass and fat percentage.
Now you have to take into account the activity of the person. Depending on the activity of the person we will multiply the value obtained previously by one of the following. Recall that is a simple approach:
– Sedentary: a person who does very little or no exercise: x 1.2
– Mild: sport 1-3 times per week: x 1,375
– Moderate: sport 3-5 times per week: x 1.55
– Strong: sport 6-7 days per week: x 1,725
– Very strong: 2 workouts a day intense physical activity: x 1.9
There are other factors that also influence such as pregnancy (+ 150-300Kcal / day) or state of lactation (+ 750kcal / day), age (> 50 years: -200kcal / day, > 75: -500Kcal men and -400Kcal / day for women) or if you are suffering from a disease (the calories will vary depending on the type).
Metabolizing food also consumes energy (specific dynamic action), depending on the macronutrient to be processed, a different amount of energy is needed, a sum of 5-10% is common to our total expenditure.