Critical Thinking


Since Wanaka I’ve been trying to negotiate my way between recovering from racing and getting ready for another race which is now just over 3 weeks away. I’ll post later about how this has been going but for the moment it’s meant I’ve had a lot of non training time where I’ve been able to indulge a passion of mine of doing yet more reading on nutrition and diet.

Over the years of reading lots about nutrition (my reading list is fairly up to date here ) I like to think I’ve become a more critical thinker when I read these books. It embarrasses me now when I look back and see how I just accepted what Patrick Holford said in his Optimum Nutrition Bible. Anything labelled a bible must me true right ? Now I believe he’s pretty much a quack having dug a little deeper. This unthinking acceptance is something that most seem to fall in to when looking at nutrition. My aim is to do my part in trying to make us all think.

Before we left the UK I had two books recommended. Racing Weight I started but didn’t finish so I intend to give my thoughts on that once back in the UK. The other was The China Study by T. Colin Campbell. I read this trying to be aware of my confirmation bias since it was at odds with what I believed. I was left a little worried about how biased it seemed. It was a guy reporting on a single study which he’d spent a huge amount of his life working on. It would be difficult for this guy to see serious flaws in it. It just didn’t ring true to me but I wasn’t really able to delve in to the detail and check myself. Instead I searched around for others that may have. Boy oh boy did I find a lot. Here are some that are worth looking at:

The main problem with the China Study is it’s observational data which can’t be used to determine causation though correlations can be found which would provide hypotheses to test. Unfortunately Campbell makes alsorts of assertions about causation. To illustrate what I mean you can observe that rain and umbrellas are seen at the same time. They’re correlated but that doesn’t give us causation. We could test two hypotheses that this may suggest: 1) putting up umbrellas causes rain or 2) rain causes umbrellas to go up. It may be neither is true and there’s some third unobserved thing causing both. This is a trivial example and I assume no one would require them tested.

However there are other examples. Personally I’ve become pretty convinced that sunscreen is great for stopping sunburn but there’s little evidence that it prevents skin cancer. I’ve clearly stated my bias but my aim here isn’t to in to the details but instead to show where critical thinking is required. Queensland had the highest rate of skin cancer in the world ( ) and lots of sun. A nice correlation… so QED right ? Well… what about they also have a massive public information campaign to use sun screen ? Now this advice may be being ignored by everyone but I would guess not. So, say this campaign has worked so sunscreen use has increased. This would mean there was a correlation between sunscreen use and skin cancer. Most of you are no probably screaming B*****IT or have stopped reading. Take a minute and accept thats your confirmation bias kicking in. Open your mind for a moment. Some hypotheses that could be tested:

  1. suncream makes it sunny (I’d thought I’d start with the daft one)
  2. suncream causes cancer. Some possible ways: a) it blocks out the UV rays that burn you but not he ones that cause skin cancer, the former allows you to spend more time in the sun getting you hit by more of the latter; b) something in the cream is carcinogenic; c) sunscreen blocks manufacture of vitamin D and it’s this deficiency that’s make you more susceptible to cancer.  ( )
  3. sun causes cancer

If you have a critical mind can you really believe that something we evolved with (ie the sun)  is really that dangerous to us. Take a look here and note we see highest rates in south of England (everyone will say yeh – the sun) but what about that band across the south of Scotland ? Could that be due to lack of sun. Look at the graphs of it’s growth. Thats scary since it’s increasing despite the message thats drilled in to us – use sunscreen to prevent cancer. Either we’re all just ignoring it (so the govt etc… should stop wasting it’s money) or the advice is wrong (again the govt could stop wasting it’s money) ! My view is – develop a tan as best you can, avoid getting burnt, avoid sunscreen as much as possible. This means if you have to be out in the sun long enough to get burnt (eg your long ride) then use sunscreen. Otherwise don’t. Just slowly build up a tan.

  1. The second example is much closer to my heart. I hear far too often that obesity causes heart disease and diabetes, or probably more often it is a risk factor for them. The latter I take to mean there is a correlation though I wonder whether most read that as meaning it causes. So… what do we see. The observation is that obese people and diabetes and heart disease are correlated. This doesn’t tell us that obesity causes diabetes anymore than it tells us heart disease causes diabetes. It’s they tend to be seen together. The chances are there’s a common underlying thing that creates both obesity and diabetes. My money is on excessive carbohydrate consumption. Thats by the by, though it does make you aware of my bias. My big concern is that this misunderstanding and the general pervasiveness of the message means we don’t question it, our money is being spent researching blind alleys, and people are getting pretty dodgy advice.

Take diabetes. Type 2 Diabetes is where someone can’t metabolise carbohydrates very well due to insulin resistance. Given carbohydrates are non essential it would seem obvious that sensible advice would be simple to stop eating carbs (do some research there’s evidence that type 2 diabetics can control their diabetes without drugs by controlling carb intake). However what advice does Diabetes UK give ?

  1. Have starchy carbs with every meal (yes – eat the very thing you’re struggling to deal with)
  2. Avoid fat, especially saturated fat.

[ ]

Yes, they’re proposing a low fat, high carb diet. This is certainly one charity I won’t give money to. Why would they give such advice ? My guess is that since diabetes is a risk factor for heart disease and we all know saturated fat cause heart disease (I won’t even go in to this here … it’s already a long post). They are mistaking a correlation for causation. An alternative hypothesis is that some underlying thing, say high carb diet, cause both diabetes and heart disease. If this hypothesis is right then they’re not only giving you a diet that will make diabetes harder to deal with but will increase your chance of getting heart disease. This will of course just increase the correlation between diabetes and heart disease. This shit terrifies me. Someone gets diabetes will go to them probably not questioning whether their advice is solid.

What is the problem here ? I think the idea of public private partnerships ( Diabetes UK Corporate Acknowledgements here ) is deeply flawed in this sort of area. The idea that a charity should be support by a profit making company just feels wrong to me. If the shareholders of said company are keen to support charity they should give directly and let the company focus on making a profit.  Better still those same shareholders could chose not to try and avoid tax but pay their full contribution to our society (come on Lewis Hamilton start the trend… I’m sure your projected billion dollar career earnings will be enough for a comfortable life even if you paid over 40% of them in tax. Come on …. do your bit. Sorry …off on a tangent) and let government support research directly.

Why are these partnerships flawed ? The problem is that companies are trying to make a profit. Thus they will have a tendency to support research that will result in something that they can sell. (ie a cure) For them to make money we need to get sick and then cure us, they definitely don’t want us just not getting sick. So, say that diet could more or less eliminate type 2 diabetes – no drug company selling diabetic drugs is going to fund research to prove this as it would completely remove their market. Even if some independent research was funded it’s unlikely to get the publicity that the more numerous, better funded research projects supported by for profit companies.

The fact Pharmaceutical companies spend more on advertising than on research ( ) should ring alarm bells that they’re more interested in selling us something than in our health.

Look at obesity and the government advice on diet. Are they being influenced by the grain industry (I’ve spent ages searching both the FSA and USDA sites but can’t find details of their funding). It’s certainly in the interests of their continued growth that we continue to grow.

This brings me to a Horizon episode I’ve just watched with a critical eye. It’s about Dr Atkins (now I’m sure most of you already have an opinion. Remember your biases. If you’ve not read his book then do so before judging. If you’ve not tried his diet, then do so. I have and IT MAKES SENSE). The tone of the show suggests they’re not Atkins sympathisers. There are a few things I noted about the show

  1. As expected the First Law Of Thermodynamics came up. They implied that Atkins somehow defied this. I’m not sure of his view but current low carb advocates ABSOLUTELY DO NOT dispute this law. Even low carb diets mean you lose weight due to eating less than you need (as detailed in the previous two posts). The tone of this documentary was clearly that it did – they pointed out that you are allowed to eat unlimited calories on this diet. The impression they gave is that people did. However… precisely because of the First Law Of Thermodynamics they clearly can’t have eaten unlimited amounts. This was probably poetic license as the show eventually came to this conclusion that with the Atkins diet people ate less calories WITHOUT having to calorie count.
  2. The next bit was a really dumb experiment. They had people eat as much as they want of a meal. The meals looked the same but some were eating one that had extra fat in the form of cream. They were trying to establish whether it was the fat in the Atkins diet that satiated the appetite. The high fat eaters ate more so they concluded that that wasn’t why Atkins worked. Our eminent scientist and expert had made a gaping error though. The meal they used was spaghetti bolognese, so both meals had tonnes of carb. They were not comparing an Atkins diet – to do this one would have had to be low carb high fat. They completely missed that it could be fat in the absence of carbs that provides satiety. Funny that later when they check out whether protein is filling they don’t suffer the same mistake.
  3. Final point is this American expert. Clearly he had a low carb bias and he commented how this diet “may have an adverse effect on health”. no science there then. In fact, you can always say something may have an effect. Of course it may … what we’re interested in is is it likely. I may win the lottery this weekend… i wish that was scientific evidence I will but I’m pretty sure it isn’t. He then goes on to say how terrible it is that these low carbers are experimenting with peoples lives. That they’re performing this massive experiment on us without  knowing whether it could all end terribly. This is bizarre on two points – low carb is still considered a fad, far from a nationwide experiment. Secondly this is precisely what the low fat advice has been for the past 20-30 years. Our government has provided this massive experiment based on virtually no evidence it would do us good. From my stand point it’s not looking like a great outcome with all these “modern” (read started since we took this advice) diseases out of control. (if you’ve not already read this then do, if you have just take another look at the graph about a third down).

Back to The China Study. What worries me about all this is that a movie “Fork Over Knifes” is coming out mid year with the author of the China Study in it ( ) … now if we have a Hollywood movie saying stop eating meat the non critical thinkers out there (the majority) are going to take this as some scientific fact.

Finally bringing this back to triathlon training ( I promise my next post will be back fully on topic) it’s important to read advice with a critical mind engaged to see if the advice is appropriate to you. Scott talks about this in his latest blog post.

This entry was posted in Critical Thinking, Nutrition, Uncategorized and tagged . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s