If you're out of shape is your BMR lower?

EvgeniZyntx

Maybe.

Abstract:

Lower than predicted resting metabolic rate is associated with severely impaired cardiorespiratory fitness in obese individuals.
Miller WM1, Spring TJ, Zalesin KC, Kaeding KR, Nori Janosz KE, McCullough PA, Franklin BA.

Abstract
Obese individuals have reduced cardiorespiratory fitness as compared with leaner counterparts. Regular exercise maintains or increases fitness and lean body mass. Lean body mass, in turn, has a direct impact on resting metabolic rate (RMR). Given these relationships, we sought to evaluate the association between RMR and cardiorespiratory fitness in obese individuals. We evaluated 64 obese individuals (78% female) with direct assessment of RMR and cardiorespiratory fitness via breath-by-breath measurement of oxygen consumption and carbon dioxide production at rest and during exercise. The mean age and BMI were 47.4 ± 12.2 years and 47.2 ± 9.2 kg/m(2), respectively. The majority of subjects, 69%, had a measured RMR above that predicted by the Harris-Benedict equation. Compared with the higher RMR group, those with a lower than predicted RMR had increased BMI, with values of 52.9 vs. 44.7 kg/m(2), P = 0.001, respectively. Analysis of those demonstrating significant effort during cardiopulmonary exercise testing (peak respiratory exchange ratio ≥1.10) revealed a significantly higher peak oxygen uptake (VO(2) peak) in the higher RMR group (17.3 ± 3.5 ml/min/kg) compared with the lower RMR group (13.6 ± 1.9 ml/min/kg), P = 0.003. In summary, a lower than predicted RMR was associated with a severely reduced VO(2) peak and a higher BMI in this cohort. These data suggest that morbid obesity may be a vicious cycle of increasing BMI, reduced cardiorespiratory fitness, muscle deconditioning, and lower RMR. Collectively, these responses may, over time, exacerbate the imbalance between energy intake and expenditure, resulting in progressive increases in body weight and fat stores.

Article: http://onlinelibrary.wiley.com/doi/10.1038/oby.2011.262/abstract;jsessionid=55F7EA672B4A52DF716286C3FE9EE6FD.f04t02


Another argument to get or stay fit - it may directly improve your resting metabolic rate.

EvgeniZyntx

And a study that might engender its own debate but also supports fitness vs RMR....

Low fitness partially explains resting metabolic rate differences between African American and white women.
Shook RP1, Hand GA2, Wang X2, Paluch AE2, Moran R3, Hébert JR4, Swift DL5, Lavie CJ6, Blair SN7.
Author information
Abstract
BACKGROUND:
High levels of obesity among African American women have been hypothesized to be partially resultant from a lower resting metabolic rate compared with white women. The aim of the current study was to determine if differences in cardiorespiratory fitness and moderate-to-vigorous physical activity are associated with differences in resting metabolic rate among free-living young adult African American women and white women.
METHODS:
Participants were 179 women (white women n = 141, African American women n = 38, mean age = 27.7 years). Resting metabolic rate was measured using indirect calorimetry, body composition using dual energy x-ray absorptiometry, cardiorespiratory fitness via maximal treadmill test, and moderate-to-vigorous physical activity using an activity monitor.
RESULTS:
African American women had higher body mass index, fat mass, and fat-free mass compared with white women but lower levels of cardiorespiratory fitness. No differences were observed between African American and white women in resting metabolic rate when expressed as kcal/day (1390.8 ± 197.5 vs 1375.7 ± 173.6 kcal/day, P = .64), but African American women had a lower resting metabolic rate when expressed relative to body weight (2.56 ± 0.30 vs 2.95 ± 0.33 mL/kg/min, P < .001). After statistical adjustment for differences in body composition between groups using linear regression models, African American women had a lower resting metabolic rate compared with white women (1299.4 ± 19.2 vs 1400.4 ± 9.2 kcal/day, P < .001). The addition of cardiorespiratory fitness reduced the differences among groups by 25%. The addition of moderate-to-vigorous physical activity did not improve the model.
CONCLUSIONS:
The present study confirms that African American women have a lower resting metabolic rate compared with their white peers, and low cardiorespiratory fitness explained 25% of this difference. Variables associated with resting metabolic rate, such as cardiorespiratory fitness, represent possible points of tailored interventions designed to address high levels of obesity seen in certain demographic groups.

lithezebra

That's fascinating. Are African American women more prone to cardiac and respiratory diseases that might have an impact on this vicious cycle? (I know that rates of hospitalization and death due to asthma are much higher in African Americans, and that that problem is likely caused at least in part by less aggressive management of asthma, because of less access to medical care, as well as by socioeconomic circumstances that increase exposure to environmental factors that promote asthma).

EvgeniZyntx

lithezebra wrote: »

That's fascinating. Are African American women more prone to cardiac and respiratory diseases that might have an impact on this vicious cycle? (I know that rates of hospitalization and death due to asthma are much higher in African Americans, and that that problem is likely caused at least in part by less aggressive management of asthma, because of less access to medical care, as well as by socioeconomic circumstances that increase exposure to environmental factors that promote asthma).

I don't know, but I'd suggest that the subject of this thread is the impact of cardiovascular fitness and metabolism. I posted that research with respect to that.

If you want to discuss social groups and disease prevalence, can I suggest a different thread?

Need2Exerc1se

Seems logical to me that it would be. Regular exercise gives your more energy, I always assumed that came from having a higher metabolic rate.

ilex70

Makes sense.

You are heavy, which makes moving more difficult, so you move less.

You move less so your cardio fitness and lean muscle mass both decrease.

Which makes moving even less pleasant, so you move less and you get more heavy...and so on, and so on.

yarwell

Seems logical, if my VO2max in ml/min/kg is poor this may well be reflected in the bottom end as well as the upper range.

My VO2max is about 35, ie 840 kcal/hr. My RMR is 1600 aka 67 kcal/h. I guess that puts my RMR at 2.79 ml/min/kg.