Author Topic: Basal Metabolic Rate and other things  (Read 4328 times)

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Offline Squarebanks

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Re: Basal Metabolic Rate and other things
« Reply #30 on: May 09, 2012, 12:54:30 PM »
On the other hand, unfortunately, there is this study:

Recidivism after weight loss is on the order of 95%.  This seems like evidence of a physiologic basic for weight regain.  And how do you separate psychology from physiology, anyway?  The brain is part of the body, after all.
This seems to contradict the main body of research. Again, most studies show a small, insignificant difference in RMR immediately following weight loss which can be attributed to hormonal changes, but this difference seems to be gone within weeks.

Do adaptive changes in metabolic rate favor weight regain in weight-reduced individuals? An examination of the set-point theory

http://www.ajcn.org/content/72/5/1088.full.pdf+html

Measured in energy-balanced conditions, RMRs of the weight-reduced women were normal relative to those of never-overweight control subjects and did not explain weight regain patterns. These findings indicate the importance of ensuring an energy-balanced state before measuring RMR after weight loss. Even after months of energy restriction, RMR normalized within 10 d of energy balance, as reflected by a return to the euthyroid state. The results also suggest that adaptive down-regulation of RMR is not a characteristic of weight-reduced individuals and does not explain their weight-regain tendency. The weight-gain tendency of obesity-prone persons appears to be caused by factors other than variations in metabolic rate.

http://www.ajcn.org/content/69/6/1064.full.pdf+html

We have spent a great deal of time looking unsuccessfully for defects in energy expenditure to explain the development of obesity and the difficulty in maintaining weight loss.

http://www.ncbi.nlm.nih.gov/pubmed/1330959?dopt=Abstract

No differences in rates of energy expenditure between post-obese women and their matched, lean controls.
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Offline jt512

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Re: Basal Metabolic Rate and other things
« Reply #31 on: May 09, 2012, 03:15:36 PM »
On the other hand, unfortunately, there is this study:

Recidivism after weight loss is on the order of 95%.  This seems like evidence of a physiologic basic for weight regain.  And how do you separate psychology from physiology, anyway?  The brain is part of the body, after all.

This seems to contradict the main body of research. Again, most studies show a small, insignificant difference in RMR immediately following weight loss which can be attributed to hormonal changes, but this difference seems to be gone within weeks.

I don't see why my comment contradicts any of the research you quoted.

As for the abstract I posted up-thread (reposted below), it appears that the last measurement of RMR was at week 30 of a weight-loss program, and the authors are merely speculating that the reduction in RMR could persist during weight maintenance.  So, this study may not contradict what you say the main body of research shows.

Quote
J Clin Endocrinol Metab. 2012 Apr 24. [Epub ahead of print]

Metabolic Slowing with Massive Weight Loss despite Preservation of Fat-Free Mass.

Johannsen DL, Knuth ND, Huizenga R, Rood JC, Ravussin E, Hall KD.

Context: An important goal during weight loss is to maximize fat loss while preserving metabolically active fat-free mass (FFM). Massive weight loss typically results in substantial loss of FFM potentially slowing metabolic rate. Objective: Our objective was to determine whether a weight loss program consisting of diet restriction and vigorous exercise helped to preserve FFM and maintain resting metabolic rate (RMR). Participants and Intervention: We measured body composition by dual-energy x-ray absorptiometry, RMR by indirect calorimetry, and total energy expenditure by doubly labeled water at baseline (n = 16), wk 6 (n = 11), and wk 30 (n = 16). Results: At baseline, participants were severely obese (x̄ ± sd; body mass index 49.4 ± 9.4 kg/m²) with 49 ± 5% body fat.  At wk 30, more than one third of initial body weight was lost (-38 ± 9%) and consisted of 17 ± 8% from FFM and 83 ± 8% from fat. RMR declined out of proportion to the decrease in body mass, demonstrating a substantial metabolic adaptation (-244 ± 231 and -504 ± 171 kcal/d at wk 6 and 30, respectively, P < 0.01). Energy expenditure attributed to physical activity increased by 10.2 ± 5.1 kcal/kg·d at wk 6 and 6.0 ± 4.1 kcal/kg·d at wk 30 (P < 0.001 vs.  zero). Conclusions: Despite relative preservation of FFM, exercise did not prevent dramatic slowing of resting metabolism out of proportion to weight loss. This metabolic adaptation may persist during weight maintenance and predispose to weight regain unless high levels of physical activity or caloric restriction are maintained.

PMID: 22535969  [PubMed - as supplied by publisher]

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