Energy balance

Energy balance is the relationship between the energy consumed through food and drink (energy intake) and the energy expended through bodily functions and physical activity (energy expenditure). This concept is fundamental to understanding weight management, as a positive energy balance (intake > expenditure) leads to weight gain, while a negative balance (intake < expenditure) results in weight loss. Energy is measured in kilocalories (kcal) or kilojoules (kJ), with the average adult requiring around 2000-2500 kcal per day, though individual needs vary based on age, gender, activity level, and metabolic rate.

In the context of Food Preparation and Nutrition, energy balance is crucial for planning balanced diets and understanding the role of macronutrients—carbohydrates, proteins, and fats—which provide energy. Carbohydrates and proteins provide 4 kcal per gram, while fats provide 9 kcal per gram. Alcohol also contributes energy (7 kcal per gram) but is not a nutrient. The basal metabolic rate (BMR) accounts for the largest portion of energy expenditure (60-75%), supporting essential functions like breathing and circulation. Physical activity and the thermic effect of food (energy used for digestion) make up the remainder.

Mastering energy balance helps students evaluate dietary choices, understand obesity and malnutrition, and apply this knowledge to real-life scenarios, such as designing meal plans for athletes or individuals with specific health goals. It also links to broader topics like nutritional needs across life stages and the impact of diet on health, making it a cornerstone of the OCR GCSE specification.