11 ms·

A recent meta-analysis came out and claimed to show that we don't have evidence right now for a link between obesity and what we've measured so far about the hu

A recent meta-analysis came out and claimed to show that we don't have evidence right now for a link between obesity and what we've measured so far about the human microbiome [0]. I can imagine a regime where two people with the same diet but with very different bacterial communities would have different health outcomes. It toally makes sense to me that if you have bacteria that are better at breaking down long fats into absorbable molecules, that you'd be getting more effective calories from the same food compared to someone without those bacteria. In fact, this has been shown to work in mice in 2006 [1]. However, in the real world, you aren't living in a sterile cage. You can sample bacteria from the environment and your microbiome is allowed to change in response to your diet. It's possible that in this regime, your diet impacts your microbiome much more than your microbiome impacts the outcome of your diet. [0](http://mbio.asm.org/content/7/4/e01018-16 http://mbio.asm.org/content/7/4/e01018-16) - Looking For a Signal in the Noise - Revisiting Obesity and the Microbiome Sze and Schloss, mBio 2016 [1] http://www.nature.com/nature/journal/v444/n7122/abs/nature05414.html http://www.nature.com/nature/journal/v444/n7122/abs/nature05... An obesity-associated gut microbiome with increased capacity for energy harvest Turnbaugh et. al., Nature 2006

gadders 10y ago
Animals used for meat production are bred for their feed conversion ratio [1] i.e. how much body mass can they produce for a given amount of food. If this can vary within other mammals, I don't see a reason why it couldn't happen in humans. I'm not sure if it would necessarily be microbiome related. [1] https://en.wikipedia.org/wiki/Feed_conversion_ratio https://en.wikipedia.org/wiki/Feed_conversion_ratio
- hammock 10y ago
  Surprised this isn't referenced more when people bring up "calories in, calories out" edit: see my child comment if you somehow think I am arguing against the concept
  - jtuente 10y ago
    Probably because it's still irrelevant to CICO. CICO doesn't tell you how much calories go in or out, rather it tells you to measure them wherever possible and make adjustments based on your weight changes.
    - hammock 10y ago
      It is relevant. You might have thought I meant it debunks it (or supports it), what I meant was it adds color to it. Conversion ratio allows you to quantify the difference from one person to another (the "adjustments based on weight change" you refer to)
      - WorldMaker 10y ago
        I still think calories in health science are the last bastion of phlogiston in any of the sciences. It's a deeply over-simplifying metric that implies a false equivalency. We estimate the calories in food by the amount of heat equivalent they create when burnt. We estimate the calorie usage of a human body by the heat it produces during the effort. None of those estimates do justice to the complex biology and chemistry processes at work: not all calories are equal, they never have been, they never will be. (Humans aren't just heat-producing machines. Digestion is nothing at all like producing raw heat from food.) ETA: It's the health science equivalent of the physics spherical cow fallacy writ large and taken dogmatically.
        DougWebb 10y ago
        It's kind of like measuring the performance of vehicles by looking only at the chemical energy of the fuel they use and how far they go on a given amount of fuel. Those seem like reasonable measurements, until you try to put jet fuel in a motorcycle or bunker oil in your car. The design, efficiency, and maintenance status of the engine matters a lot.
        jtuente 10y ago
- elsherbini 10y ago
  In fact, many livestock are given subtheraputic antibiotic doses[0] to increase their weight gain, but the mechanism isn't known for why it works. In that case it feels like it almost has to be a shift of the bacterial community that causes it. [0] https://scholar.google.com/scholar?as_ylo=2015&q=subtherapeutic+antibiotic+use+in+livestock&hl=en&as_sdt=0,22&as_vis=1 https://scholar.google.com/scholar?as_ylo=2015&q=subtherapeu...
- chriskanan 10y ago
  While that's true, the hypothesis in the paper is consistent with feeding antibiotics to livestock to improve their feed conversion ratio by decreasing the diversity of bacteria in their microbiomes [0, 1]. [0] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1804117/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1804117/ [1] https://en.wikipedia.org/wiki/Antibiotic_use_in_livestock https://en.wikipedia.org/wiki/Antibiotic_use_in_livestock
semi-extrinsic 10y ago
This is often what happens with meta-analyses: many people have convinced themselves there is a pattern based on limited-but-good data, have asserted so in the literature such that it's almost accepted as fact, and then a meta-analysis actually crunches the numbers and finds little to no statistical support for the claim. A recent well-documented case is that of jellyfish blooms in the oceans: http://theconversation.com/how-time-poor-scientists-inadvertently-made-it-seem-like-the-world-was-overrun-with-jellyfish-61564 http://theconversation.com/how-time-poor-scientists-inadvert... Just to clarify, I'm not saying these people are stupid. But rather that Feynman was very right when he said that the easiest person to fool is yourself.

gadders 10y ago

Animals used for meat production are bred for their feed conversion ratio [1] i.e. how much body mass can they produce for a given amount of food. If this can vary within other mammals, I don't see a reason why it couldn't happen in humans. I'm not sure if it would necessarily be microbiome related. [1] https://en.wikipedia.org/wiki/Feed_conversion_ratio https://en.wikipedia.org/wiki/Feed_conversion_ratio

hammock 10y ago
Surprised this isn't referenced more when people bring up "calories in, calories out" edit: see my child comment if you somehow think I am arguing against the concept
- jtuente 10y ago
  Probably because it's still irrelevant to CICO. CICO doesn't tell you how much calories go in or out, rather it tells you to measure them wherever possible and make adjustments based on your weight changes.
  - hammock 10y ago
    It is relevant. You might have thought I meant it debunks it (or supports it), what I meant was it adds color to it. Conversion ratio allows you to quantify the difference from one person to another (the "adjustments based on weight change" you refer to)
    - WorldMaker 10y ago
      I still think calories in health science are the last bastion of phlogiston in any of the sciences. It's a deeply over-simplifying metric that implies a false equivalency. We estimate the calories in food by the amount of heat equivalent they create when burnt. We estimate the calorie usage of a human body by the heat it produces during the effort. None of those estimates do justice to the complex biology and chemistry processes at work: not all calories are equal, they never have been, they never will be. (Humans aren't just heat-producing machines. Digestion is nothing at all like producing raw heat from food.) ETA: It's the health science equivalent of the physics spherical cow fallacy writ large and taken dogmatically.
      - DougWebb 10y ago
        It's kind of like measuring the performance of vehicles by looking only at the chemical energy of the fuel they use and how far they go on a given amount of fuel. Those seem like reasonable measurements, until you try to put jet fuel in a motorcycle or bunker oil in your car. The design, efficiency, and maintenance status of the engine matters a lot.
        jtuente 10y ago
elsherbini 10y ago
In fact, many livestock are given subtheraputic antibiotic doses[0] to increase their weight gain, but the mechanism isn't known for why it works. In that case it feels like it almost has to be a shift of the bacterial community that causes it. [0] https://scholar.google.com/scholar?as_ylo=2015&q=subtherapeutic+antibiotic+use+in+livestock&hl=en&as_sdt=0,22&as_vis=1 https://scholar.google.com/scholar?as_ylo=2015&q=subtherapeu...
chriskanan 10y ago
While that's true, the hypothesis in the paper is consistent with feeding antibiotics to livestock to improve their feed conversion ratio by decreasing the diversity of bacteria in their microbiomes [0, 1]. [0] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1804117/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1804117/ [1] https://en.wikipedia.org/wiki/Antibiotic_use_in_livestock https://en.wikipedia.org/wiki/Antibiotic_use_in_livestock

semi-extrinsic 10y ago

This is often what happens with meta-analyses: many people have convinced themselves there is a pattern based on limited-but-good data, have asserted so in the literature such that it's almost accepted as fact, and then a meta-analysis actually crunches the numbers and finds little to no statistical support for the claim. A recent well-documented case is that of jellyfish blooms in the oceans: http://theconversation.com/how-time-poor-scientists-inadvertently-made-it-seem-like-the-world-was-overrun-with-jellyfish-61564 http://theconversation.com/how-time-poor-scientists-inadvert... Just to clarify, I'm not saying these people are stupid. But rather that Feynman was very right when he said that the easiest person to fool is yourself.