The Body's Energy Balance Is Determined by the Following Parameters:
Basal Metabolic Rate (BMR):
This is the amount of energy required for the body to function at a basic level (without any physical activity). It represents the minimum energy necessary to sustain vital life functions over a 24-hour period if we were lying down, not moving, and not eating - essentially doing nothing.
Total Metabolic Rate (Total Energy Expenditure):
This includes the energy required for basal metabolism plus the energy needed to carry out daily activities (which can vary significantly from person to person). It also includes the energy used to digest and process the food we consume.
Both BMR and total energy expenditure can vary widely between individuals. When trying to lose excess weight, one of the most important pieces of information is knowing your individual BMR. With this knowledge, it's possible to adjust your daily caloric intake appropriately to promote weight loss and avoid plateaus before reaching your goal weight.
How to Measure Basal Metabolic Rate
The most accurate way to measure BMR currently is through indirect calorimetry, which calculates energy expenditure by measuring the amount of oxygen inhaled and carbon dioxide exhaled. This method provides an exact, numerical result.
Devices like InBody analyzers, which measure body composition, can also estimate BMR. However, these devices calculate it using a formula based on fat-free body mass. While this estimate may be accurate for individuals with average body composition, in people who are overweight, it can often be misleading - either underestimating or overestimating actual BMR.
By using indirect calorimetry to precisely determine your BMR, you can make more effective changes to your diet or adjust the intensity and frequency of your physical activity in order to achieve your desired results (e.g. weight loss in the case of excess body weight).
Additional Insights from Indirect Calorimetry
Indirect calorimetry can also provide another important value: the respiratory quotient (RQ). This shows the extent to which your body relies on burning carbohydrates or fats when it needs energy.
This information is particularly valuable when aiming to lose weight. For example, if despite a significant lifestyle change your weight isn’t decreasing or is decreasing very slowly, the RQ may reveal that your body is still primarily burning carbohydrates. In such cases, a dietitian can help adjust your nutrition to encourage your body to shift from carbohydrate metabolism to fat metabolism.
Why Indirect Calorimetry Matters
Currently, indirect calorimetry is the only method that can provide such detailed and accurate insights into your metabolism. It delivers real, measurable data about your energy needs and how your body uses energy - making it an essential tool for developing effective and personalized dietary and lifestyle strategies.
