Friday, October 24, 2014

Weight loss advice from fat people

There is an assumption that is easy to make about health advice: that the health of the person giving advice is a good test of the correctness of their theories. This is a terrible mistake.

Here are a couple of reasons why it is a mistake:

  • It conflates what people advocate with what they do.

    This goes in two directions. Someone could advocate something that they don't adhere to, or they could adhere to it but do something else that, known to them or not, changes the outcome.

    For example, someone could claim to gain fat on a very low carb diet, but not realise that those high-protein peanuts they are eating have signficant carbohydrate in them. Or, on the other hand, they could claim great loss, but not mention that were also taking a hormone that turned out to have made all the difference.

  • It doesn't take into account what the person is struggling with.

    Someone with a strong genetic propensity to gain fat and who has been obese for a long time is simply never going to have the results from a fat loss intervention that someone with a more moderate genetic risk who has not ever been fat.

    A hard gainer is never going to get as bulked up as a natural bodybuilder type, even if they find the perfect protocol.

This latter problem would even seem to suggest that people who struggle or have struggled with health problems are better judges of what works and what doesn't. There is some truth to this: If someone with a health problem manages to improve it, that positive outcome suggests that someone else in the same position might also see improvement following the same plan.

Moreover, sick people, fat people, people who can't meet their goals through mainstream advice are often more likely than others to hit upon fundamental scientific misconceptions that are holding them back, or new therapies that are incredibly effective. And yet, a person who has recovered from severe diabetes, for example, may still have health measurements that don't inspire great confidence in someone who is starting out with less severe issues.

However, this is also a mistake!

If you want to evaluate whether someone's health advice is good, comparing where they started with where they are is a good starting heuristic, but it doesn't take the place of evaluating scientific research. There can always be coincidences, or relevant information you are not aware of.

People who do health research and promote their conclusions are aware that their own health is under scrutiny. They can hold themselves up as positive anecdotes of what is possible, and they should.

Anecdotes, like observational correlations, are useful for generating hypotheses. A randomised controlled trial that refutes the hypothesis must be considered better evidence than an anecdote or even a correlation generated from a large data set. On the other hand, a negative anecdote can single-handedly refute certain kinds of scientific claim.


It bothers me when people criticise the theories of public figures based on their personal successes. It equally bothers me when people applaud those who have lucked out genetically, and who can basically do no wrong: they will look fantastic under a variety of abuses.

Take advice from fat people, if the advice is scientifically tenable.

Ignore advice from thin people if it doesn't stand up to scrutiny.

8 comments:

  1. Thanks for this, Amber! You have a knack for laying the issues out clearly. I've seen people discount advice from still-overweight people, even if those people have lost half their body weight so far. I've also seen people slavishly follow the advice of naturally lean people whose body compositions don't change no matter what protocol they follow. People need to do their own research, and -- this step can't be left out -- they need to track very carefully, one variable at a time, how their own bodies respond to protocol changes. It's true that we are not all wildly different from one another, but there's enough difference at important margins that seemingly small things, such as a few grams of absolute dietary carbohydrate intake, can have substantial impact on individual results.

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  2. Your assessment is accurate. Another issue that is important is that overweight people usually become insulin resistant so that what they eat gets rapidly stored as fat, thus they remain hungry, craving carbs, and tired because their bodies are not giving them needed energy. Like getting paid well by your company, with direct deposit, but the bank won't let you make a withdrawl. This becomes a vicious cycle leading to greater weight gain. The only way I broke out of this--after reading Gary Taubes Good Calories, Bad Caloires--was very low carb/KETOGENIC diet. Even with my strict diet, and exercise, the weight loss has been very slow. Additionally, I am middle-aged which makes it harder.
    Nan

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  3. Hey Amber, good post. It's resonant for me, as someone trying to build a nutrition consulting practice. I feel like I need to "look the part." (I mean, why would anyone trust an overweight or unhealthy looking nutritionist.) But the truth is, many times, looks can be deceiving. I've seen plenty of clients who looked great on the outside but who were total messes on the *inside.* The shape of my body and the state of my health don't always, every second of every day, reflect the *knowledge* I have and can share with others. It's rough out there -- people are very quick to judge based on someone's physical appearance. But if someone is, say, 260 pounds, maybe they *started* at 350, and while someone taking a quick look at them might think they're out of shape or unhealthy, they're actually doing great on whatever plan they're following!

    My weight doesn't fluctuate much, but the way I *feel* about my body does. And when I'm having a less-than-confident day, it's hard for me to push that aside and feel like I can still be taken seriously as a health/nutrition professional.

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    1. Exactly! ☺

      These days when I see someone overweight, I recognise that I have no idea what they are going through or where they've been.

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  4. I think this also falls into the territory of a logical fallacy; 'tu quoque' or to put it plainly disregarding a persons argument because they are a hypocrite. Also known as an " appeal to hypocrisy ". Just because someone is fat, doesn't mean their theory or argument is wrong.

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  5. Unfortunately, when dealing with humans, we end up having to contend with Ethos, Pathos, and Logos.
    http://sachighmedia.com/visual/wp-content/uploads/2012/04/04-ethospathoslogos.jpg

    A compelling argument consists of a balance of all 3 elements in most cases, and failing to "practice what you preach" and suffering from the same malady you claim to be able to cure - sadly, two strikes against ethos before you've even opened your mouth. Unless your interlocutor is particularly scientifically literate, citing research will have little effect. Empirical data is only part of the formula to a well-crafted argument.

    It's not ideal, but it's how humans work.

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    1. What about the case where the person has lost a lot of weight, but are still overweight, or what if their own research works generally, but not their own special case? That's not a failure to practise.

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