Tää vuos on ollu kaikille rankka. Toisille enemmän, toisille vähemmän.
2 t ·
''When Anssi Manninen gets so triggered from me pointing that citing blogs & narrative review papers does not ‘prove’ energy balance is false that he emails your PhD advisor
''
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Kyse varmaan tästä: :D
2020 Dec 3
Do Lower-Carbohydrate Diets Increase Total Energy Expenditure? An Updated and Reanalyzed Meta-Analysis of 29 Controlled-Feeding Studies
David S Ludwig 1,
Stephanie L Dickinson 2,
Beate Henschel 2,
Cara B Ebbeling 1,
David B Allison 2
8 t ·
There is a new study by Ludwig et al (a researcher who has touted the superiority of low carb diets for a while now) that concluded low carb diets increase energy expenditure (EE) in long(er) term studies. Basically this study re-analyzed Kevin Hall’s original meta-analysis from 2017 but separated the studies into those less than 17 days or longer than 17 days
Study:
https://pubmed.ncbi.nlm.nih.gov/33274750/
This meta-analysis was well done from a statistics perspective, but there are major GAPING holes that aren't explained
First off, they chose to omit metabolic chamber data when doubly labeled water (DLW) data was available. Metabolic chamber is the gold standard for energy expenditure and is a DIRECT measurement of EE while DLW is merely a surrogate. So why would Ludwig choose to use DLW when a direct measurement was available? This would be like using skinfold data instead of MRI measurement of body fat even when both were available! It makes ZERO sense
Using DLW data biases the long term studies towards low carb (LC) superiority as DLW has NOT been validated for EE measurements during LC diets & has been consistently demonstrated to OVERESTIMATE energy expenditure compared to non-LC diets. This is likely due to the change in respiratory quotient (RQ) (ratio of O2/CO2) during low carb diets which causes greater than predicted increase in CO2. Since RQ is used in the calculation to determine EE from DLW, this causes an overestimation of EE when using DLW for low carb diet studies. Additionally, the increased loss of body water from LC diets also exacerbates this overestimation. This is likely why ONLY studies using DLW have shown significant increases in EE in favor of LC diets, whereas metabolic chamber studies have failed to show the same outcomes
Citations:
https://www.biorxiv.org/content/10.1101/403931v3
https://pubmed.ncbi.nlm.nih.gov/27385608/
Furthermore, there was evidence of biasing the data to favor LC diets. One of the studies (Rumpler et al.) in the meta-analysis was 35 days long but Ludwig chose data from the 28 day mark where the difference between low carb diets and low fat diets were the greatest (~200 kcal/d difference) however on day 35 there was no difference between the two diets. No good explaination was provided for why this timepoint was chosen compared to day 35. During days 28-35 the subjects were moved from a deficit to maintenance. This might make sense as to why Ludwig chose this time point if not for his own studies which were done at maintenance and included in the same meta-analysis. The choice to using the data from day 28 instead of day 35 does not make sense and is not adequately explained by the researchers
Citation:
https://pubmed.ncbi.nlm.nih.gov/1989409/
Further, in other studies (Abbot et al.) Ludwig claims that the low carb diet increased energy expenditure more than the control diet, but this is not supported by the data in the paper and the conclusions from the researchers themselves
Citation:
https://pubmed.ncbi.nlm.nih.gov/2305878/
Finally, there is NO data demonstrating increased fat loss from LC diets in these studies. In fact, every single study which 'demonstrated' increased EE (up to supposedly ~400 kcal/d difference) from LC diets did NOT show any significant increase in fat loss when compared to the low fat diet. In fact, several of the studies showed a slight (not statistically significant) advantage of fat loss to the low fat diets. If LC diets TRULY cause a REAL increase in EE, why don’t we observe increased fat loss? Because the increase is likely not real & simply due to a data artifact of DLW not being a viable measurement of EE for LC diets
In summary: the current meta-analysis does not support the researchers’ conclusions that LC diets increase EE. It merely supports the non-validity of DLW for use in assessing energy expenditure during LC diets
Shawn Baker
you called me out on this... I await your response and analysis
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