Calories are the energy stored in food that your body uses for all its functions. Understanding how calories work is essential for weight management. Every food and beverage you consume contains calories, and every activity you perform burns calories. The balance between calories consumed and calories burned determines whether you maintain, gain, or lose weight.

Basal Metabolic Rate (BMR)

Your Basal Metabolic Rate (BMR) is the number of calories your body needs to function at rest. This includes basic bodily processes like breathing, circulation, cell production, and nutrient processing. BMR accounts for about 60-75% of your total daily calorie expenditure.

Several factors influence your BMR:

• Age: BMR decreases as you age due to loss of muscle mass
• Gender: Men generally have higher BMR than women due to more muscle mass
• Body Composition: Muscle burns more calories at rest than fat
• Genetics: Some people have naturally faster metabolisms
• Hormones: Thyroid function and other hormonal factors affect metabolism

Total Daily Energy Expenditure (TDEE)

Your Total Daily Energy Expenditure (TDEE) is your BMR plus the calories you burn through physical activity. This includes:

• Exercise Activity Thermogenesis (EAT): Calories burned during intentional exercise
• Non-Exercise Activity Thermogenesis (NEAT): Calories burned through daily activities like walking, cleaning, or typing
• Thermic Effect of Food (TEF): Calories burned digesting, absorbing, and processing food (about 10% of total calories)

To maintain your current weight, you need to consume approximately the same number of calories as your TDEE. To lose weight, you need a calorie deficit, and to gain weight, you need a calorie surplus.

Calorie Surplus vs. Deficit

The key to weight management lies in the balance between calorie intake and expenditure:

Calorie Surplus

A calorie surplus occurs when you consume more calories than your body burns. This excess energy is stored as body fat and muscle mass. A moderate surplus (250-500 calories above TDEE) is recommended for healthy weight gain, especially when combined with resistance training to maximize muscle growth.

Calorie Deficit

A calorie deficit occurs when you consume fewer calories than your body burns. This forces your body to use stored energy (fat and muscle) to meet its needs. A moderate deficit (250-500 calories below TDEE) is recommended for healthy, sustainable weight loss. Crash diets with severe deficits can lead to muscle loss, nutrient deficiencies, and metabolic slowdown.

Quality Over Quantity

While calorie balance is the primary driver of weight change, the quality of those calories matters for overall health and well-being:

• Nutrient Density: Foods high in nutrients (vitamins, minerals, fiber, protein) provide more health benefits than calorie-dense, nutrient-poor foods
• Satiety: Protein, fiber, and healthy fats keep you feeling full longer, helping you maintain a calorie deficit more easily
• Energy Levels: Complex carbohydrates and healthy fats provide sustained energy, while simple sugars cause energy crashes
• Long-term Health: A diet rich in whole foods reduces the risk of chronic diseases like heart disease, diabetes, and certain cancers

Remember, weight management is not just about counting calories, but also about making informed choices that support your overall health and wellness goals.