Frequently Asked Questions

In the journey toward obtaining and maintaining a healthy weight, understanding one's metabolism can be crucial to succeeding. Often, people struggling with weight loss mistakenly suspect the cause is a slow metabolism. It is possible, just not as probable as they may think. But how can you accurately assess your metabolic rate? Enter indirect calorimetry, a sophisticated and precise method to measure Resting Energy Expenditure (REE). This technique can provide invaluable insights into your body's unique energy needs, enabling tailored and effective weight loss strategies.

What is Indirect Calorimetry?

Indirect calorimetry is a non-invasive method used to measure the amount of oxygen consumed and carbon dioxide produced by the body. These measurements help calculate the REE, which is the amount of energy your body requires to maintain basic physiological functions while at rest. Unlike predictive equations that estimate REE based on factors like age, sex, weight, and height, indirect calorimetry offers a personalized and accurate assessment.

How Does It Work?

The process of indirect calorimetry involves breathing into a mouthpiece or a mask connected to a metabolic cart. The device analyzes the respiratory gases to determine the rate of oxygen consumption and carbon dioxide production. The test typically takes about 30 minutes, during which the subject remains at rest. The resulting data provides a precise measurement of the REE, reflecting the body's actual metabolic rate.

Benefits of Indirect Calorimetry

1. Accurate Measurement of Metabolic Rate

One of the primary benefits of indirect calorimetry is its accuracy. Standard predictive equations can often misestimate REE, especially in individuals with unique metabolic rates, such as those who are obese. Indirect calorimetry provides a direct measurement, ensuring that the calculated energy requirements are precise and tailored to the individual.

2. Personalized Weight Management Plans

Accurate REE measurements enable dieticians and nutritionists to create personalized dietary plans that align with an individual's specific energy needs. This personalization helps in setting realistic calorie intake goals, thereby enhancing the effectiveness of weight loss programs. Whether the goal is to create a calorie deficit for weight loss or to maintain a healthy weight, knowing the exact REE is crucial.

3. Identifying Metabolic Adaptations

Weight loss can induce metabolic adaptations, such as a decrease in REE, making further weight loss more challenging. Indirect calorimetry can detect these changes, allowing for timely adjustments in dietary and exercise regimens. Understanding these adaptations helps in preventing plateaus in weight loss and supports long-term weight management.

4. Optimizing Exercise Programs

Alongside dietary adjustments, indirect calorimetry can inform exercise programs. Knowing the REE allows fitness professionals to design workout plans that complement the individual's metabolic rate, maximizing the effectiveness of physical activity in burning calories and enhancing overall fitness.

5. Monitoring Progress and Adjusting Strategies

Regularly measuring REE through indirect calorimetry can help track metabolic changes over time. This ongoing monitoring is essential for adjusting weight loss strategies as needed. It ensures that the approach remains effective and aligned with the body's current metabolic state, thereby supporting sustained weight loss and health improvements.

6. Enhancing Patient Understanding and Engagement

For many, seeing the scientific data behind their metabolic rate can be enlightening and motivating. Indirect calorimetry provides concrete numbers that can help individuals understand their bodies better, fostering a more informed and engaged approach to weight management.

Conclusion

Indirect calorimetry stands out as a powerful tool in the realm of weight loss and metabolic health. Its precision and ability to provide personalized insights make it an invaluable asset for anyone serious about achieving their weight loss goals. By accurately measuring REE, this method empowers individuals and healthcare professionals to craft customized, effective, and sustainable weight management strategies. Embrace the power of indirect calorimetry, and unlock the true potential of your metabolism on your journey to a healthier you.

Sources

1. Compher, C., Frankenfield, D., Keim, N., & Roth-Yousey, L. (2006). Best practice methods to apply to measurement of resting metabolic rate in adults: a systematic review. Journal of the American Dietetic Association, 106(6), 881-903.
2. Weijs, P. J., & Vansant, G. A. A. M. (2010). Indirect calorimetry: Accuracy and clinical applications in nutrition. Nutrition in Clinical Practice, 25(4), 377-388.
3. Ravussin, E., & Bogardus, C. (1989). Relationship of genetics, age, and physical fitness to daily energy expenditure and fuel utilization. American Journal of Clinical Nutrition, 49(5), 968-975.
4. Müller, M. J., Bosy-Westphal, A., Kutzner, D., & Heller, M. (2004). Metabolically normal but obese individuals are resistant to the adverse effects of obesity on the cardiometabolic risk profile. Obesity Reviews, 5(4), 202-208.
5. Rosenbaum, M., & Leibel, R. L. (2010). Adaptive thermogenesis in humans. International Journal of Obesity, 34(Suppl 1), S47-S55.
6. Foster, G. D., Wadden, T. A., Phelan, S., Sarwer, D. B., & Sanderson, R. S. (2003). Obese patients' perceptions of treatment outcomes and the factors affecting them. Archives of Internal Medicine, 163(17), 2069-2075.
7. Müller, M. J., Enderle, J., & Bosy-Westphal, A. (2016). Changes in energy expenditure with weight gain and weight loss in humans. Current Obesity Reports, 5(4), 413-423.
8. Weinsier, R. L., Hunter, G. R., Zuckerman, P. A., & Darnell, B. E. (2003). Low resting metabolic rate and fat gain in women: a possible explanation for the thrifty gene hypothesis. American Journal of Clinical Nutrition, 77(3), 499-504.
9. Manore, M. M. (2005). Exercise and the Institute of Medicine recommendations for nutrition. Current Sports Medicine Reports, 4(4), 193-198.
10. Fontaine, K. R., & Cheskin, L. J. (1997). Self-efficacy, attendance, and weight loss in obesity treatment. Addictive Behaviors, 22(4), 567-570.

These sources collectively provide a strong evidence base for the benefits of using indirect calorimetry to measure REE, particularly in the context of obesity and metabolic variability.

Indirect Calorimetry:

1. Role in Assessment Indirect calorimetry is recognized as a valuable tool for accurately measuring an individual's resting metabolic rate (RMR). This measurement is crucial for determining energy needs and tailoring dietary interventions for weight management.

2. Clinical Use: The research supports the use of indirect calorimetry in clinical settings to provide personalized nutrition recommendations. By measuring RMR, dietitians and healthcare providers can create more precise calorie prescriptions that align with the individual's metabolic requirements.

3. Accuracy: Indirect calorimetry is considered more accurate than predictive equations for estimating RMR, particularly in individuals with obesity. Predictive equations often have significant variability and may not accurately reflect the metabolic rate of those with higher body weights.

4. Implementation: The research encourages the implementation of indirect calorimetry, when available, as part of a comprehensive assessment in weight management programs. This practice can enhance the effectiveness of dietary interventions and support better outcomes for individuals undergoing weight loss treatment.

In summary, the research advocates for the use of indirect calorimetry to provide accurate and individualized assessments of energy needs, which can improve the design and effectiveness of weight management interventions for adults with overweight and obesity.

Sources

1. Raynor HA, Champagne CM. Position of the Academy of Nutrition and Dietetics: Interventions for the Treatment of Overweight and Obesity in Adults. J Acad Nutr Diet. 2016 Jan;116(1):129-147. doi: 10.1016/j.jand.2015.10.031. PMID: 26718656.

1. Basal Metabolic Rate (BMR) and Resting Metabolic Rate (RMR) are often used interchangeably, but they are measured under slightly different pretest conditions and typically result in different values. The difference between BMR and RMR usually falls within a certain range, and understanding this difference can be useful when calculating energy needs.

Definitions

• Basal Metabolic Rate (BMR): The number of calories your body needs to maintain basic physiological functions at complete rest. It is measured under very strict conditions after a full night’s sleep and 12 hours of fasting in a controlled environment.
• Resting Metabolic Rate (RMR): Similar to BMR, but measured under less strict conditions. It accounts for the calories burned while at rest in a post-absorptive state, i.e. 4-6 hours after eating, no exercise or stimulants that day.

Percentage Difference

The calorie difference between BMR and RMR is generally small but noticeable. On average, RMR is about 5-10% higher than BMR. This difference is due to the less stringent conditions under which RMR is measured, which can include the energy cost of digestion and minimal activity.

Calculation Example

Suppose an individual's BMR is calculated to be 1,500 calories per day. Using the 5-10% range, we can estimate the RMR as follows:

• 5% Higher RMR:
                             RMR = 1,500 calories × 1.05 = 1,575 calories/day  
• 10% Higher RMR:
                              RMR = 1,500 calories × 1.10 = 1,650 calories/day 

Summary

In percentage terms, the Resting Metabolic Rate (RMR) is generally about 5-10% higher than the Basal Metabolic Rate (BMR). This slight increase accounts for the more relaxed conditions under which RMR is measured, reflecting a slightly higher energy expenditure compared to BMR.

Sources

Several reputable sources confirm the difference between Basal Metabolic Rate (BMR) and Resting Metabolic Rate (RMR), typically highlighting that RMR is about 5-10% higher than BMR due to the less stringent conditions under which it is measured. Here are some key sources that discuss and validate this difference:

• National Academy of Sports Medicine (NASM)
  • The NASM explains that RMR can be 10% higher than BMR due to less restrictive testing conditions. This source is widely used in the fitness and health industry for training and educational purposes.
  • Reference: National Academy of Sports Medicine. (n.d.). Understanding Metabolism. Retrieved from NASM

• American Council on Exercise (ACE)
  • The ACE notes that RMR measurements are typically higher than BMR by 10%, as RMR includes the energy cost of maintaining basic physiological functions under less controlled conditions.
  • Reference: American Council on Exercise. (n.d.). Basal Metabolic Rate: What Is It and Why Does It Matter?. Retrieved from ACE Fitness

• Journal of the American Dietetic Association
  • A study reviewed in this journal highlights the differences between BMR and RMR, indicating that RMR is typically higher by around 10% due to the less stringent testing conditions.
  • Reference: Frankenfield, D., Roth-Yousey, L., & Compher, C. (2005). Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. Journal of the American Dietetic Association, 105(5), 775-789. doi:10.1016/j.jada.2005.02.005

• Journal of Applied Physiology
  • This journal includes research articles discussing metabolic rates and the slight increase in RMR over BMR, commonly cited as around 10%.
  • Reference: Muller, M. J., Bosy-Westphal, A., & Klaus, S. (2004). Metabolically active components of fat-free mass and resting energy expenditure in humans: recent lessons from imaging technologies. Journal of Applied Physiology, 95(5), 1956-1963. doi:10.1152/japplphysiol.00338.2003.

Thames Diagnostics offers BMR or RMR Metabolic testing using indirect calorimetry.

In most cases, you do not need a referral to use Thames Diagnostics. However, some insurance plans may require a referral from your primary care physician. Please check with your insurance company before scheduling an appointment at Thames Diagnostics.