Understanding Energy Balance

Energy balance is a description of physics, not a diet. It explains what happens to body mass over time; it says nothing about whether a diet is nourishing.

The components of expenditure

• Basal metabolic rate — the largest component for most people, typically 60–70%.
• Thermic effect of food — the energy used to digest and process what you eat.
• Non-exercise activity — walking, fidgeting, standing, daily movement.
• Deliberate exercise — usually a smaller share than people expect.

Why both sides move

Reduced intake tends to lower spontaneous movement and, as body mass falls, resting expenditure declines too. This adaptation is a normal physiological response, and it explains why progress slows rather than continuing in a straight line.

What it does not tell you

Two diets with identical energy content can differ enormously in protein, fibre, and micronutrients. Energy balance answers one question; nutrient density answers another.