Fat Mass (RFM) a Stronger Predictor of Mortality than BMI: Dutch Cohort Study

This Dutch study published in the journal Obesity examined the link between body composition and death risk. They compared two measures: BMI (body mass index) and a newer measure called RFM (relative fat mass). The key finding is that RFM was a better predictor of mortality than BMI. People with higher RFM (more fat mass) had a greater risk of death, even if their BMI wasn't in the obese range. Interestingly, muscle mass also played a role. When the researchers considered muscle mass alongside fat mass (RFM), the link between both measures and death risk became even stronger. This suggests that individuals with high-fat mass and low muscle mass are at especially high risk. The study suggests that focusing on RFM instead of BMI might be more accurate when assessing mortality risk. Additionally, accounting for muscle mass is crucial for a complete picture.

Key Findings:

• RFM as a better predictor: The study compared two measures: Body Mass Index (BMI) and Relative Fat Mass (RFM). RFM, a newer measure, showed a stronger association with all-cause mortality compared to BMI. This suggests RFM might be a more accurate indicator of mortality risk.

• Muscle mass plays a role: Both RFM and BMI correlated with muscle mass. Interestingly, the association between RFM and mortality became stronger after accounting for muscle mass. This implies that individuals with higher fat mass and lower muscle mass have a greater risk of death.

• BMI's limitations: While previous research indicated a "J-shaped" or "U-shaped" link between BMI and mortality (meaning both very low and very high BMI increase risk), this study highlights that BMI might not be the most accurate measure. Individuals with mild to moderate obesity according to BMI might not necessarily have a higher mortality risk.

What we already knew:

• Numerous studies established a connection between BMI and mortality, with a higher risk at both ends of the BMI spectrum (very low and very high).

• Some studies suggested a potential survival benefit for individuals with mild to moderate obesity based on BMI categorization.

What this study adds:

• RFM, a more precise indicator of body fat percentage, proves to be a stronger predictor of mortality risk compared to BMI.

• Adjusting for muscle mass strengthens the link between both RFM and BMI with mortality. This suggests that the combination of high fat mass and low muscle mass significantly increases the risk of death.

Implications for future research:

• The study recommends using RFM instead of BMI when examining the link between "obesity" and mortality risk.

• Accounting for muscle mass alongside fat mass measurements is crucial for a more accurate interpretation of mortality risk.

Word count: 346 words (within the requested limit of 700 words).

Additional points to consider:

• The study utilizes 24-hour urinary creatinine excretion as a marker of muscle mass, which might have limitations in accuracy compared to more advanced methods.

• Further research is needed to explore the underlying mechanisms explaining the stronger association between RFM and mortality compared to BMI.

This study, delves into the intricate relationship between body composition markers and mortality risk, aiming to provide crucial insights into better predictive measures. Study findings shed light on the limitations of traditional metrics like Body Mass Index (BMI) and advocate for the adoption of Relative Fat Mass (RFM) as a more accurate predictor of mortality risk.

Understanding RFM and BMI: Unveiling the Differences

RFM, a novel marker of adiposity, surpasses BMI in its ability to predict whole-body fat percentage. Derived from height and waist circumference (WC), RFM offers a more nuanced reflection of body fat percentages, accounting for sex-specific differences. Notably, RFM values, varying between genders, present a more physiologically reflective measure of adiposity. Contrastingly, BMI, while widely used, exhibits limitations, especially in aging populations. This study reveals an intriguing age-related pattern, wherein BMI's association with increasing age in men takes on an "inverted U-shaped" trajectory, possibly due to its stronger correlation with muscle mass.

Unraveling the Obesity Survival Paradox: RFM vs. BMI

The phenomenon of the obesity survival paradox, previously linked with BMI, undergoes scrutiny in this study. Unlike BMI, RFM emerges as a robust predictor of all-cause mortality, emphasizing the inadequacies of BMI in capturing mortality risk accurately. These findings challenge the conventional wisdom surrounding obesity-related mortality risks, advocating for a paradigm shift towards RFM-based assessments.

Reinforcing Associations: The Role of Muscle Mass

A notable revelation from this study pertains to the impact of muscle mass on the associations between adiposity markers and mortality risk. Adjusting for muscle mass not only strengthens the associations of both RFM and BMI with all-cause mortality but also underscores the necessity of accounting for muscle mass in adiposity assessments.

Limitations and Future Directions

Despite the significant insights provided, our study acknowledges certain limitations. The inability of RFM to distinguish between visceral and subcutaneous fat highlights the need for further research using advanced imaging techniques. Additionally, the observational nature of our study calls for cautious interpretation, urging future investigations to elucidate causality.

To Summarize

• RFM and age: A linear relationship existed between RFM (relative fat mass) and age in both women and men. This implies that fat mass tends to increase with age in this population.

• BMI and age: While BMI (Body Mass Index) also increased with age in women, a unique inverted-U shape emerged in men. This suggests that BMI might peak around 60 years in men.

• Muscle mass and age: Muscle mass (reflected by 24-hour urinary creatinine excretion) steadily declined with age in women, while this decline became evident only after 60 years in men.

• RFM vs. BMI and muscle mass: BMI showed a stronger association with muscle mass compared to RFM, suggesting BMI might be a better indicator of overall muscle content.

• Mortality risk: A higher RFM was linked to a greater risk of death during the follow-up period (median 18.4 years). This association remained significant even after adjusting for various factors like age, sex, and health conditions.

• Muscle mass and mortality: Lower muscle mass (indicated by lower 24-hour urinary creatinine excretion) was associated with increased mortality risk in both sexes.

Additional Points:

• The study highlights the importance of considering both fat mass (RFM) and muscle mass when assessing mortality risk.

• While BMI provides some insight, RFM might be a more specific indicator of fat accumulation and its association with mortality.

• Age-related changes in body composition differ between men and women, with women experiencing a more consistent decline in muscle mass.

Limitations:

• The study relies on a single measure of muscle mass (urinary creatinine excretion), which might not fully capture the entire picture.

• Further research is needed to explore the underlying mechanisms linking body composition to mortality risk.

Conclusion: Advocating for RFM as a Superior Predictor

In conclusion, our study underscores the superiority of RFM over BMI in predicting mortality risk in the general population. By highlighting the nuanced relationship between adiposity markers, muscle mass, and mortality risk, we advocate for the widespread adoption of RFM in clinical and public health settings. Our findings pave the way for refined risk assessment strategies, facilitating more targeted interventions to mitigate mortality risks associated with adiposity.

This comprehensive analysis elucidates the intricate interplay between adiposity markers, muscle mass, and mortality risk, positioning RFM as a promising avenue for enhancing risk prediction models and guiding personalized health interventions.

Journal Reference

Suthahar, N., Zwartkruis, V., Geelhoed, B., Withaar, C., Meems, L. M. G., Bakker, S. J. L., Gansevoort, R. T., van Veldhuisen, D. J., Rienstra, M., & de Boer, R. A. (2024). Associations of relative fat mass and BMI with all-cause mortality: Confounding effect of muscle mass. Obesity (Silver Spring, Md.), 32(3), 603–611. https://doi.org/10.1002/oby.23953

Related

https://healthnewstrend.com/essential-amino-acids-may-reduce-liver-fat-in-teens-with-pcos-and-obesity

Medical Disclaimer

The information on this website is for informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.