Could you start the engine of your car without putting gasoline in it? Impossible! The relationship between the human body and calories is the same. They are essential to our body; we could not live without them. However, the word “calorie” is often the source of various prejudices, fears, and confusions! Suspected of making weight gain, they are our only source of energy.
But then, we very often ask ourselves the question: “How Many Calories Should I Eat A Day?“. The answer cannot be generalized and must be verified on a case-by-case basis. There are many factors to consider, which is why the caloric needs are specific to everyone.
Here is an article that will help you estimate your daily calorie needs and better understand why the body uses these calories.
What is a calorie?
A calorie is an ancient unit of energy. It was used in physics and corresponded to the energy required to heat one gram of liquid water from 14.5 to 15.5 ° C.
The calorie is no longer part of the international system of units; it is only used in dietetics to express the energy value. The calorie can be converted to joule, where one calorie = 4.184 joules.
Thus, 1000 calories = 1 kilocalorie, the abbreviation of which is kcal. It is the latter term that is most commonly used in the field of nutrition.
The energy value of food
- 1 g of lipids provides 9 kcal
- 1 g of carbohydrates provides 4 kcal
- 1 g of protein provides 4 kcal
Note also that 1 g of alcohol provides 7 kcal, almost as much as lipids. However, the drink does not contain any nutrients that the body can use; these are called empty calories.
To calculate the total energy value of food, you have to figure the number of carbohydrates, fats, and proteins in that food, convert them to calories and then add them up.
The caloric values of food must always be put into perspective. On their own, they do not make it possible to know whether it will follow again, a loss or maintenance of the weight of the food contains absorbing nutrients, if it is of good quality, etc. This is why it is not relevant to state that a portion of food makes you gain or lose weight.
When do we consume energy?
If there is one thing to remember, as long as the body is alive, it burns energy! Indeed, the body uses energy for all physiological activity:
- Movements (daily, physical activity);
- Brain activity;
- Heartbeat and adaptation of heart rate;
- Regulation of body temperature;
- Cell renewal …
It is believed that the body does not need energy at night because we are sleeping. This is, however, false! The body is in constant need of power to ensure the functionality of its physiological processes, as well as the maintenance of its vital functions: your heart continues to beat, your breathing does not stop, digestion is in progress, your temperature body temperature should be maintained at 37.5 ° C …
Of course, we consume less energy at night than during physical exertion, but we still drink it.
You will understand: the human body constantly consumes energy! This is why calories from food are essential for the body, and too much calorie restriction can greatly slow down the basal metabolism, which is not ideal for the body!
How many calories should you consume per day?
Calculate your daily energy need
The daily energy requirement, or BEJ, corresponds to the amount of energy required by the body to function normally and compensate for its energy expenditure. This energy can only be provided by food via the calories contained in food.
Each person has a specific BEJ because it depends on several data particular to each: sex, age, weight, height, physical activity …
To determine how many calories per day you should be consuming, here is the calculation to use:
BEJ = MB x NAP
(BEJ: Daily energy requirements / MB: Basal metabolism / NAP: Level of physical activity)
To calculate your basal metabolism, understand how it works, and find out how to improve it, we invite you to read this article: How to calculate your basal metabolism? (Ongoing redaction)
The level of physical activity (NAP) corresponds to the different energy expenditures linked to activities of daily living according to their duration and intensity. These activities are classified according to a coefficient:
- Coefficient 1: Sleep, nap, rest while lying down
- Coefficient 1.2: Sitting position: television, computer, meals, transport, writing …
- Coefficient 2.2: Standing position: short trips around the house, cooking, housework, shopping, dishes …
- Coefficient 3: Walking, gardening, yoga, a manual profession of medium intensity and performed standing
- Coefficient 3.5: Manual discipline of high intensity and performed standing (masonry, mechanics, etc.)
- Coefficient 5: Sport, intense professional activities (forestry work, building, etc.)
To calculate your NAP:
- Determine the average times per day spent on each type of activity
- Multiply each duration by the corresponding coefficient
- Add up the results
- Divide by 24 (since there are 24 hours per day)
In a simpler but less precise way, you can also use this summary memo of the average NAP according to your average activity over the day:
- Impotent: NAP 1.2-1.3
- Inactive: NAP 1.4-1.5
- Average activity: NAP 1.6-1.7
- Significant activity: NAP 1.8-1.9
- Very important activity: NAP> 2
The more frequent your physical activity, the more your NAP will increase. Over time, your NAP will also help improve your basal metabolism.
This is how you can increase your daily calorie energy needs.
Warning: it is not because you play sport every day that you are an active person … If your job is sedentary and you spend a lot of time sitting, sport alone will not be enough to increase by several levels your NAP.
How many calories per day to lose, gain or maintain weight?
When you want to see your weight change, you always try to know how many calories per day you should ideally consume. This is an entirely appropriate approach since the total number of calories ingested is related to the weight. Indeed, the energy intake will have an impact on it.
Let’s start with the weight loss. This is possible thanks to a simple calorie deficit, implemented gradually. To determine how many calories you should be consuming per day, you must first calculate your BEJ (from the formula stated earlier) and then subtract 200 to 300 kcal.
The reduction can be made by slices of 50 kcal per week so as not to shock the body.
For example, if your BEJ is 2200 kcal, you can opt for a calorie deficit of 2000 kcal per day.
However, beware of restrictive diets and excessive calorie deficits, which will only be effective in the short term. You risk regaining the lost weight (or even more) because these feeding methods are not sustainable over time.
To determine how many calories per day you need for weight gain, the method is the same but in reverse! You start by calculating your BEJ, to which you add 200 kcal or more depending on your goals. The calorie balance then becomes excess, which helps promote weight gain.
Maintaining weight is done simply by consuming the calories we need. A simple BEJ calculation will let you know how many calories per day you need.
Calorie intake recommendations
The National Agency for Food, Environmental, and Occupational Health Safety (ANSES) has defined a daily caloric intake to cover the body’s needs.
For men, the average energy requirement is between 2400 and 2700 kcal.
For women, the recommendation is 2000-2200 kcal. This is, of course, an average; your intake may be higher or lower depending on your profile and your lifestyle.
Children and adolescents
Children and adolescents have specific caloric needs because their body needs specific energy for growth and development.
The previous BEJ calculation to determine how many calories per day we need also applies to children and adolescents. We must add a multiplication factor: growth energy (Ec).
This gives us: BEJ = MB x NAP x Ec
To keep things simple, general recommendations exist for children and adolescents.
In children from 3 to 9 years old, the recommended total energy intake varies from 1200 kcal for the young and/or less active to 2000 kcal for the most senior and/or the most active.
For adolescents aged 10 to 18, the recommended total energy requirements are 1900 to 3000 kcal. These needs are similar to adults, but they are increased because of the energy consumed for growth.
The growth energy is all the stronger in boys, who, in the event of intense and very regular physical activity, can reach energy needs of more than 4000 kcal.
In the elderly, food is a vital and convivial part of everyday life. It is reflected in the quality of health, the length of life, and the person’s autonomy.
However, it is difficult to determine an average caloric need for the whole of this population because it is very heterogeneous.
Some seniors are in excellent health, play sports, garden, travel, and are very independent. Others are more fragile and have a condition that creates specific nutritional needs.
The lifestyle, the medical profile, and the possible disorders will significantly vary the energy needs.
However, and contrary to popular belief, the calorie needs of the elderly are not lower than those of adults! They may even be higher with regular physical activity or a metabolic disorder.
In all cases, restrictive diets should be prohibited because they expose to high risks of undernutrition.
For this population, we calculate the number of calories per day thanks to the recommendation of 30 to 40 kcal per kg of body weight (except in the case of pathology where the caloric intake is different).
Pregnant and breastfeeding women
Pregnant women have increased energy needs because they must cover the basic needs of the mother as well as the specific needs related to pregnancy.
Indeed, the growth of the fetus and the placenta, the development of the uterus, and the mammary glands require additional energy. The needs will gradually increase as the pregnancy progresses.
The European Food Safety Authority (EFSA) has proposed a simple calculation to find out how many calories per day to consume, which is retained as an energy recommendation. It is necessary to start from the initial analysis of the BEJ via the multiplication of the basal metabolism by the NAP, to which we add:
- In the 1st trimester: +70 kcal
- In the 2nd trimester: +260 kcal
- In the 3rd trimester: +500 kcal
For breastfeeding women, the calorie needs are similar to those of pregnant women in the 3rd trimester, ie their BEJ + 500 kcal. Lactogenesis indeed requires additional energy and therefore increases energy requirements.
The importance of nutritional quality
If calories are indeed transformed into energy by the body, all calories are not equal and are not of the same quality. To function, the body and its organs also need specific nutrients found in different food categories. There are seven categories of food:
- The drinks ;
- Fruits and vegetables ;
- Dairy products ;
- Meats, fish, and eggs;
- Fatty substances ;
- Fatty, salty and sweet products.
Imagine that our daily energy requirement is 2100 kcal. If we eat only one food category, we expose ourselves to nutritional deficiencies and various dysfunctions of the organism (organs, muscles, metabolism…), even by consuming our 2100 kcal!
Whatever your needs and calorie intake, your diet should always be as varied as possible to be balanced.
When and how many calories do we burn per day?
Daily energy expenditure (DEJ) is made up of 4 to 5 aspects:
- The basal metabolism, which represents 60% of the DEJ;
- The level of physical activity (NAP), which accounts for about 25% of the DEJ;
- Thermoregulation, which represents 10% of the DEJ;
- The dynamic and specific action (ADS) of food, which represents 8 to 10% of the DEJ;
- And a possible particular physiological state: growth, pregnancy, scarring following an accident, etc.
It can be difficult to estimate how many calories per day we burn because we all have different daily lives and paces!
To give you a little idea, here’s how many calories you can burn during common daily activities:
- Sleep for 7 hours: 382 kcal
- Shower for 15 minutes: 62 kcal
- Brush your teeth for 2 minutes: 4 kcal
- Drive for 30 minutes: 60 kcal
- Walking for 30 minutes (6 km / h): 149 kcal
- Running errands for 1 hour: 130 kcal
- Do household chores for 1 hour: 95 kcal
- Iron clothes for 30 minutes: 66 kcal
- Gardening for 30 minutes: 205 kcal
- Cooking a classic meal: 93 kcal
- Play with children for 30 minutes: 186 kcal
- Watch TV for 30 minutes: 28 kcal
- Sitting at the desk behind a computer screen for 1 hour: 102 kcal
Sport (for 1 hour):
- Cycling (30 km / h): 1220 kcal
- Running (12 km / h): 940 kcal
- Jump rope: 900 kcal
- Boxing: 670 kcal
- Climbing: 600 kcal
- Football: 600 kcal
- Swimming: 520 kcal
On an average day, a woman burns about 2000 kcal, and a man 2500 kcal.
How many calories per day should we consume if we exercise?
As seen above, your daily calorie requirement depends on various factors, including your physical activity and sport. For its contraction, the muscle uses energy (carbohydrates and fats), oxygen, and water. During the physical effort, the body uses substrates to form ATP (adenosine triphosphate) molecules or energy. These substrates are mainly carbohydrates, fats, and proteins as a last resort.
Therefore, if you increase the frequency and intensity of your sporting activity, your calorie needs will also increase since you will exercise more.
Also, sport is an excellent way to speed up your primary metabolism. The more you move, the more you tone your body. You then increase your muscle mass.
As explained above, muscles need a lot of energy to be maintained. Muscle tissue is also the most energy-consuming element! A muscular body will therefore require more power and therefore calories at rest. This is how your basal metabolism increases.
To know how many calories per day you should consume if you are athletic, the calculation is always the same: BEJ = MB x NAP.
The resulting calorie total is higher due to a higher than average NAP.
Overall, athletes, whether they are high performance or amateurs, have a higher than average calorie requirement. These needs are to be estimated more
specifically according to the nature of the activity, the frequency, and the intensity. The needs of some athletes can go up to 3500 kcal!