Calories / Kcal : How Caloric Deficit and Surplus Work and How They Affect Your Weight
Calories are often associated with diets, weight-loss regimens and body weight control. In reality, they represent the unit of measurement of the energy that the body obtains from food and drinks to carry out daily activities. From breathing and blood circulation to walking, work or intense physical activity, the human body constantly needs energy.
Understanding how caloric intake works can help consumers make more informed food choices and manage their body weight more effectively.
What is a Caloric Deficit?
A caloric deficit occurs when you consume fewer calories than your body needs to maintain its current weight. In this case, the body uses energy reserves – mainly body fat – to compensate for the difference. Over time, this leads to weight loss.
Example: If your body needs 2,000 kcal per day and you only consume 1,600 kcal, you are in a deficit of 400 kcal.
It is important for a caloric deficit to be moderate and sustainable. Very restrictive diets – below 1,200 kcal per day for women or 1,500 kcal for men – can lead to nutritional deficiencies, muscle loss, fatigue and a slowing of the metabolism. Specialists recommend a moderate deficit of 300–500 kcal per day for gradual and healthy weight loss.
What is a Caloric Surplus?
A caloric surplus occurs when you consume more calories than your body needs. The extra energy is stored, mainly in the form of fat tissue, leading to weight gain over time.
Example: If your body needs 2,000 kcal and you consume 2,400 kcal, you have a surplus of 400 kcal.
Not all caloric surpluses are equal: a surplus from nutritious foods (proteins, healthy fats, complex carbohydrates) can support muscle building, especially when associated with physical training. A surplus from ultra-processed foods, high in simple sugars and saturated fats, however, is associated with a higher risk of obesity, cardiovascular disease and metabolic disorders.
How Are Calories Calculated?
The daily caloric requirement varies according to several factors: age, sex, height and weight, level of physical activity, and general health status.
To estimate the basic metabolic rate (BMR) – i.e. the number of calories the body burns at rest – the Harris-Benedict or Mifflin-St Jeor formulas are commonly used. These are subsequently multiplied by an activity factor to obtain the total daily energy requirement (TDEE).
Practical example:
- A 35-year-old woman, weighing 65 kg, 165 cm tall, with moderate physical activity, needs approximately 2,100–2,200 kcal/day.
- A caloric deficit of 400 kcal/day would bring her to approximately 1,700–1,800 kcal/day for gradual weight loss.
The Role of Macronutrients in Caloric Balance
Calories come from three main macronutrients, each with different roles:
- Proteins: 4 kcal/gram. Essential for muscle maintenance and repair, they also contribute to satiety.
- Carbohydrates: 4 kcal/gram. The main source of energy for the brain and muscles.
- Fats: 9 kcal/gram. Important for hormonal functions, absorption of fat-soluble vitamins and cell structure.
A balanced diet does not mean eliminating one macronutrient, but adjusting the proportions according to individual needs and health goals.
Practical Recommendations from InfoCons
Do not follow extremely restrictive diets without the advice of a nutritionist or doctor.
Read food labels to understand the caloric content of products and make more informed choices.
Be aware that the caloric content indicated on packaging is an average and may vary depending on preparation method and portions.
Physical activity is an essential part of caloric balance: even moderate exercise helps maintain a healthy weight and improves overall health.
Avoid "miracle" diets that promise rapid weight loss, as these are often unsustainable and can be harmful in the long term.
InfoCons Consumer Protection reminds you that balanced nutrition and an active lifestyle are the most effective long-term strategies for maintaining a healthy weight. For personalised information, always consult a specialist.
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