Sunday, April 10, 2016

It's a bit more complicated than that - fat and sugar

Ian Leslie has written an interesting long read for the Guardian: "The Sugar Conspiracy".

It's a good illustration of how science works. Science is a great idea and, I would argue, the best thing we have for finding out if something is true or not. I like Jerry Coyne's definition of science, broadly construed: "as the use of reason, empirical observation, doubt, and testing as a way of acquiring knowledge." Unfortunately, like many great ideas, it's carried out by fallible humans, and so whilst in principle, and practice, science has given us great leaps forward, that progress is often constrained by the personalities and foibles of those involved in the debate at the time. Max Planck's remark neatly sums this up: “A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.” Leslie, referencing that same remark (and showing empirical support for it), shows how nutritional advice has followed this pattern. (To see another illustration of this in practice, you should read the excellent Big Bang by Simon Singh).

However, I have a few problems with the article:

The first is that it talks favourably about the Atkins diet, deriding those who questioned it. However, the Atkins diet is a fad diet, and not a very good one.

For starters, Leslie rightly says "Controlled trials have repeatedly failed to show that people lose weight on low-fat or low-calorie diets, over the long-term.". The problem is, the Atkins diet is also a low calorie diet.

The Atkins diet advocates high fat and protein, and virtually no carbohydrates. The diet results in people eating food that leaves them feeling full for longer. Consequently, they have a reduced calorie diet because they don't eat as many calories. Whilst patients may lose weight on the Atkins diet, the diet is not risk free - for example it may lead to damage to tissue and vascular damage, and could lead to life threatening complications.

The article also seemed a bit disingenuous to claim "Only in the last few years has it become acceptable to study the effects of Atkins-type diets." Atkins first book may have been published in 1972, but it was the 2002 book "Dr. Atkins' New Diet Revolution" that really saw the Atkins diet take off (see the Google ngram graph). It didn't take long for the scientific community to look at the efficacy and safety of low-carb diets, see "Atkins and other low-carbohydrate diets: hoax or an effective tool for weight loss?" from The Lancet in 2004 and "Safety of low-carbohydrate diets" from 2005. These are both over a decade old - does that qualify as the "last few years"?




The Atkins diet also restricts intake of fruit and vegetables - diets high in fruit and veg lower the chances of a number of diseases.

On top of that, ideally the goal of a weight loss programme should be for the weight to stay off. A recent (albeit small) study showed the Atkins diet was no more effective than other weight loss programmes, but that after the 6 month trial, the 12 month follow up showed that weight had been put back on.

My second issue with the article is that it leaves one with the impression that fats are okay, and sugar is bad, and that reducing sugar is the key to resolving the obesity epidemic (and there is an epidemic - some people will try and tell you that there isn't one, but it has become harder to deny when there are more obese people than underweight people in the world) - but it's much more complicated than that. Cutting out carbohydrates is will not give a healthy, balanced diet, after all carbohydrates are the bodies preferred energy source - in fact the NHS Eat Well guide is a very good way of thinking about how much, and of what, you should be eating. However, following a diet plan can be useful, and there is also a guide on the pros and cons of a number of diets out there on the market. Indeed cutting out carbohydrates will result in less fruit and veg being consumed - something Robert Lustig does not recommend.

This leads to another grumble - Leslie should have distinguished between refined carbohydrates ("sugar") and complex carbohydrates, like starch. The article is about the refined carbs - what people put in their tea, and yet when advocating low carb diets, this can include cutting out complex carbohydrates as well. It's a distinction that should have been made.

Lastly, Taubes is lauded for his book, but he is not without his critics - some of those criticisms are the same that Leslie is making: conclusions being made with insufficient evidence, which Taubes is also guilty of when he concludes that low carb diets are the key.

Diet is not the only factor when it comes to weight management. It is emerging that the microbiome of the gut may play a part, and of course, the other important factor absent is levels of exercise. The article makes it look like cutting out carbs will solve obesity, but his isn't the case.

Whilst there are lots of factors involved in a person's weight, achieving or maintaining a healthy weight isn't complicated. You must expend more calories than you take in to lose weight. It's simple physics - whilst people may lose weight at a different rate, the body gets its energy from the food that is eaten. If more of that energy is being used than is being taken in, then weight will reduce. As Michael Pollen said "Eat food. Not too much. Mostly plants". I would add - move yourself often.

The problem though is not informing people of these things, it's actually changing people's behaviour (see page 13 of this link) so that the information is taken on board - but if the information provided is misleading, as I feel that Ian Leslie's article is, then that won't help in that regard.

Tuesday, March 29, 2016

Thoughts on terrorism

A couple of memes have popped up quite frequently in my social media feeds regarding the recent atrocities. Both I feel I should share, but for different reasons.

First we have this, which I take issue with:



Here are the groups responsible for those attacks. I have gone for those attacks that most closely match the numbers of dead. Sadly, some of the above cities have been the victims of more than one attack.

PlaceDateResponsible
Lahore27/03/2016Tehrik-i-Taliban Pakistan
Istanbul19/03/2016ISIS
Brussels22/03/2016ISIS
Iskanderia25/03/2016ISIS
Maiduguri16/03/2016Boko Haram
Peshawar16/03/2016Unknown
Ankara13/03/2016Kurdistan Freedom Falcons
Grand Bassam13/03/2016AQIM

Some terrorism may have no religion, but three of these groups are overtly religious, and do what they do in the name of their religion:

  • Boko Haram - founded with the goal of establishing an Islamic state, and now allied with ISIS.
  • ISIS - Specifically set up to have a world wide Islamic caliphate.
  • Tehrik-i-Taliban Pakistan - an umbrella group for various Sunni Islamist militants, one of their goals being the enforcement of their interpretation of Sharia law.

I am not saying that all Muslims are terrorists, but to say that terrorism as a whole has no religion is to deny part of the problem. Some terrorism has religious motivation. As Sam Harris* has said:

"Many countries in Latin America have legitimate grievances against the U.S. Where are the Guatemalan suicide bombers? Where are the Cherokee suicide bombers, for that matter? If oppression were enough, the Tibetans should have been practicing suicidal terrorism against the Chinese for decades. Instead, they practice self-immolation, for reasons that are totally understandable within the context of their own religious beliefs. Again, specific beliefs matter, and we deny this at our peril. If the behavior of Muslim suicide bombers should tell us anything, it's that certain people really do believe in martyrdom. Let me be very clear about this: I'm not talking about all (or even most) Muslims - I'm talking about jihadists. But all jihadists are Muslim. If even one percent of the world's Muslims are potential jihadists, we have a terrible problem on our hands. I'm not sure how we deal with 16 million aspiring martyrs - but lying to ourselves about the nature of the problem doesn't seem like the best strategy."

Sam Harris's 1% is not that far fetched - this is from a Pew poll "The World's Muslims: Religion, Politics and Society" that took a dispassionate look at the beliefs of Muslims around the world:

They may be in the minority, but many Muslims feel suicide bombing is often or sometimes justified.

The second meme deals with the issue of understanding ISIS specifically:


Firstly, yes, the meme has a number of mistakes - some of the details aren't quite correct, in terms of locations, dates etc. Also, two of the attacks were not by ISIS - Ankara on March 15th, and San Diego (I'm guessing it means San Bernardino). I'm also not sure if the statement that ISIS is killing more Muslims than any other group is true.

That said, the central point is important - our media is biased in its reporting. This is partly understandable, we feel more empathy to those closest to us. The Paris and Brussels attacks shook me far more than the other attacks mentioned in these memes, because I know people there, I've visited there. It resonates far more than places across the globe I've not visited, and don't know anyone that's from there. This in no way diminishes the grief, pain and sorrow of each of these attacks, but to feel equal empathy for all the world's ills is to leave one in such a well of pity and despair, I don't think there would be any way out.

Whilst the West's disproportionate reporting of terrorism is understandable, a consequence is that it very much seems that ISIS is out to get us in the West specifically. But they're not - they want to establish a worldwide Islamic caliphate under their interpretations of Islamic Law, whether you identify as Muslim or not.

I haven't got the first clue how to bring world peace, but when it comes to dealing with terrorism, you have to identify the problem itself, and ignoring parts of it - in this case the motivations, and the atrocities occurring very far from our doorstep - we are prone to being duped by those who claim to offer solutions to our perceived problems, and not the actual issue at hand.

*Sam Harris seems to provoke a lot of controversy around what he says. If you have issue with some of Sam Harris' other views, that's cool, but please let's just focus on the quote I have used and nothing more.

Sunday, March 27, 2016

In defense of the BMI

I've heard a few friends dissing the BMI recently, including being sent an article titled "BMI is a terrible measure of health", Katherine Hobson. I think the they are wrong to do so, and this is why.

The BMI has it's limitations, but it is certainly not terrible, and I think it can be very useful for helping people lead a healthy lifestyle, so here is a defense of the BMI. If you don't know what the BMI is, read this first.

One of the most common criticisms I hear is that the BMI will put athletic people into the overweight/obese categories because muscle is more dense than fat. BMI is very crude, and doesn't take these things into account. This seems a ridiculous limitation - if someone is athletic and sporty, are they actually in need of a metric to find out if they're a healthy weight? As Hobson says: "The goal of using any obesity indicator should be to identify people with excess fat, since that fat has been associated with bad health outcomes". I agree, and as such, it seems silly to use an obesity indicator on professional athletes.

Hobson goes on to summarise some research: "A study by researchers at UCLA published this month in the International Journal of Obesity looked at 40,420 adults in the most recent U.S. National Health and Nutrition Examination Survey and assessed their health as measured by six accepted metrics, including blood pressure, cholesterol and C-reactive protein (a gauge of inflammation). It found that 47 percent of people classified as overweight by BMI and 29 percent of those who qualified as obese were healthy as measured by at least five of those other metrics. Meanwhile, 31 percent of normal-weight people were unhealthy by two or more of the same measures. Using BMI alone as a measure of health would misclassify almost 75 million adults in the U.S., the authors concluded."

However, given the population of the U.S. at the time of the study was 322 million, it means that over 75% of the population are correctly classified. The research is behind a pay wall, so it's a shame to not see the full paper (I also wonder how those other metrics compare with each other).

On top of that, if the goal is to find people with excess fat, it is not fair to knock the BMI when it is being compared to tests with a different goal: to assess cardiometabolic health.  BMI might not be the best indicator of cardiometabolic health, but then that's not its goal. That said, with over a 75% success rate, it doesn't seem to be too shabby!

This study was commissioned because employers in the US wanted to penalise employees up to 30% of health insurance costs if they failed certain health metrics, including BMI. The study wanted to find out how BMI compared to six indicators of cardiometabolic health. If insurance companies, or employers, are misusing the BMI when it comes to health insurance payments, that's hardly the fault of the test, that's the fault of people not using it appropriately.

A better criticism of the "athletes get measured overweight" is that BMI doesn't take into account bone, fat or muscle, it just lumps the entire body together as a single unit. As stated, we are looking for a measure of excess fat - and the fact that BMI doesn't look at fat directly is a legitimate criticism. So what happens when we compare BMI to a more direct measure of body fat, our stated goal for this metric?

study compared BMI to skin fold thickness (which is a more direct measure of body fat), to assess the BMI cut offs (for healthy weight, obesity etc) in different ethnicities. They found those who were obese by BMI were obese by skin fold thickness 50 - 80% of the time depending on ethnicity and gender); and those who were not obese by BMI were not obese by skin fold thickness 85% to 99% of the time.

Clearly BMI is a crude, but useful, estimate of a person's body fat.

The BMI began as an epidemiological tool for populations, and so will always be a problem when applied to an individual. It's similar to the lottery - if enough people play, someone will win, but it won't be you.

In this case we're dealing with more realistic odds - if you're obese by BMI, it's not a certainty that you will get Type II diabetes for example, but it is much more likely. When looking at large populations, the effects of obesity can be seen, and they are not good for health.

So how does BMI compare when looking at other metrics for obesity? Is BMI a fair assessment of whether or not someone's weight is too high?

Measuring someone's waist circumference can be used to assess whther they are obese. The BMI compares against a measure of waist circumference pretty well. A study showed that 6% of people will have a healthy BMI, but an obese waist, and also, 6% of people will have an obese BMI, but a normal waist. The remaining 88% will have a waist circumference that matches their BMI.

An even better metric than waist circumference and BMI is,the hip to waist ratio, which takes into account where fat is stored in the body a little more - fat stored around the belly is associated with poorer health outcomes than fat stored elsewhere ("apples", those who store fat around the wait tend to do worse than "pears" who store more fat on the hips). The hip to waist ratio is a very good metric for assessing helath, and better than the BMI as far as I'm concerned. There is another metric that is better than BMI as well: the Surface-based Body Shape Index, lead to a more accurate predictor of mortality, compared to BMI.

So why am I still defending the BMI when other metrics are available, that also look to be better indicators of health? Well it can be harder to do accurately measure the hip to waist ratio, as there are different ways to do it. Likewise, the Surface-based Body Shape Index is again a little more complicated. BMI is very simple - you just need your weight and height, and if you're terrible at maths, it's very easy to calculate online.

Why is this important? Well, being overweight and obese greatly increases your risks for a number of diseases. However, biology is complex, and the effects of excess fat are not fully understood - whilst being overweight and obese can increase your chances of various maladies, once you have those maladies, you may be less likely to die from them than someone of a healthy weight.

Clearly, there is more to health than just measuring obesity - more than one metric should really be taken into account. However, obesity is still a significant risk to health. People severely underestimate the risks associated with lifestyle, and it's not a case of not knowing the risks. Simply knowing the risks isn't always enough. Let's take smoking, everyone knows it's a risk, however, not everyone fully appreciates this fact. Knowledge of smoking risk comes in four levels:

Level 1: having heard that smoking increases health risks.

Level 2: being aware that specific diseases are caused by smoking.

Level 3: accurately appreciating the meaning, severity, and probabilities of developing tobacco related diseases.

Level 4: personally accepting that the risks inherent in levels 1–3 apply to one’s own risk of contracting such diseases.

It's that level 4 - where you actually realise that the risks will apply, directly, to your own health, that many smokers seem not to get. I suspect that when it comes to other risk factors people don't have that fourth level of awareness.

Sadly, the fantastic  NHS tool "Atlas of Risk" is no longer running, however, it was based on a number of large data sets, and it would show you the leading causes of death in the UK, both nationally and locally, and would also show the biggest risks leading to those deaths. Thankfully, I got a screen grab of the tool for a lesson I taught. Here are the national risks, leading to death, in this country:


Being obese, not eating enough fruit and veg, and not getting enough exercise are the 4th, 5th and 6th most risky things that you can do if you don't want to die earlier than you otherwise would, from natural causes. The 1st and 3rd leading risks are also associated with obesity.

At the end of the day, the hardest bit about staying healthy is the effort you put in, because it's not that complex. You can ignore all those fad (and often expensive) diet plans - just follow the NHS EatWell plate. Get some regular exercise. It will make a difference.

That said, we will all die eventually, and people are free to be obese, smoke and do other activities that negatively impact their health.

But for those that want to improve or maintain their health, I don't think the BMI should be disregarded. Firstly, as we have seen, it's not perfect, but is still a useful indicator. However, secondly, and I think more importantly, it can help monitor your progress, in a way that the better waist to hip ratio may fails at.

Most people tend to lose excess fat evenly, they don't reduce fat in some areas and not others. Therefore, if people were using the hip to waist ratio, this would stay the same, even if significant changes to lifestyle were bringing about a reduction in over all excess fat. However, a person's BMI profile would improve in that time.

The BMI was initially developed as a tool for epidemiological studies - it was always going to have flaws when applied to individuals. But if you recognise those limitations, there's no reason why it can't be there in the tool kit available to assess one's health.

Saturday, March 26, 2016

Thoughts on Batman vs Superman

I enjoyed Batman vs Superman. It was good, but not great. I think Ben Affleck as Batman was one of the highlights though.

Here's why I think that, it will contain spoilers.

Firstly, I thought Affleck was great as Batman. Things I liked about this Batman:

1. Not once did I think about Affleck playing Batman whilst watching it, it just made me think of Batman.

2. As well as Affleck's performance, it also look great - the costumes were spot on.

3. Nice to see Batman doing a suitably bad ass looking work out. You don't get to be Batman without some hard graft in the gym.

4. Batman doing some detective work. One criticism I read was "Why didn't Batman work out the White Portuguese was a boat?", which seems silly, because he did in the end.

Some have taken issue with Batman killing people. Yes, that's not his way in the comic books, but Batman's been killing on the big screen since Michael Keaton (I'd argue not all of these are definitely kills, but the vast majority are):


It's easier in comics when you're dealing with still frames to have non lethal fights.

What I didn't like though were Batman's use of firearms, given this:
 

Granted, he was using the guns dropped by others, but still. However, that was a minor gripe. It would have made the film better to see Batman only using the guns he picked up as clubs.

I was more uncomfortable with seeing Batman break another man's neck - granted it was a Darkseid hinting dream sequence, but seeing Batman physically kill a man in that fashion seemed the most un-Batman like. This is not rational given the life ending injuries he has given, as shown in the video above.

I've also heard that people didn't like the slightly more cruel take on Batman in the film, but Miller's Batman was clearly an influence, and whilst All Star Batman and Robin is seen as an else worlds story, Miller has said that Year One, All Star Batman and Robin,  and the Dark Knight series are all in the same universe. One of the big criticisms of All Star was the sadistic take on Batman - so maybe they shouldn't have looked as much to Miller's take? Either way, I though it was a great take on Batman, and I look forward to more.

The final fight with Superman and Batman was good - I've read of some complaining it wasn't, and that there should have been more intricate choreography, but I don't think so, their trading of blows was good - I guess with the hype people wanted more.

I also liked Wonder Women - she kicked ass! That said, I've not really read much Wonder Woman, so no idea if she reflects her comic book alter ego so well or not.

I like the hints of things from the past, eg:



Lastly, I liked the plot. It made sense to me - I know others struggled with it, but I think they've taken things a bit too seriously. Yeah, there are plot holes, but that's not uncommon, and if you just sit back for the ride, I don't think it's as terrible as some reviewers made out.

Yes, there were missed opportunities to maybe deal with more serious topics like social problems, politics and xenophobia, but this is Batman vs Superman. I wasn't going there for a complex plot, I was going there for some fun, and to watch Batman and Superman slug it out. The plot is certainly where the film couldn't have been improved, but I don't feel it needs to receive the savaging it has.

Whilst film critics can be useful and informative, this film was never going to contend for an Oscar, and I think the proof in the pudding will be the audience's response. I do hope they disagree with the critics, and that the critical panning doesn't jeopordise the DC Cinematic Universe plans - the film hints at lots more to come, and I want to see it all!



Sunday, February 14, 2016

How to predict the future with dreams

There are two ways:

Firstly: Make the prediction after the event has happened.

Let's go over the first way, using an imaginary example of a dream from Richard Wiseman's excellent book Paranormality to illustrate the point:

"At two o'clock in the morning you are right in the middle of a rather sinister dream in which you are driving along a dark country lane. Eric Chuggers, your all-time favourite rock star is sitting in the passenger seat, and the two of you are chatting easily. Suddenly a giant purple frog jumps out in front of the car, you swerve to avoid the frog but go off the road and hit a tree. However, tonight your cat feels a bit peckish and decides to pester you for food. As she jumps onto the bed you wake up from the dream with a vague memory of Eric Chuggers, a giant purple frog, a tree and impending death."

In a couple of days time you wake to the news that Eric Chuggers was driving through the city, swerved to avoid a car, and hit a lamp post. You realise that your dream was a prediction of the future!

However, this doesn't stack up on closer inspection. Firstly, in the dream, Eric is not driving, but in the passenger seat; it's a dark country lane, not the city; there is no purple frog; Eric slams into a lamppost and not a tree.

However, the dream gets twisted as a prophecy, given that all of the incidents are broadly similar. Of course, the other dreams that you have had that week are forgotten. And so it is for most dreams - the majority go forgotten, as real life events don't trigger our memory of them.

So it is with "true" tales of prophecy - it's not uncommon to see, after the fact, people coming forward with how they predicted a catastrophic event, because they had this or that dream that if you squint your eyes, kinda matches the real life events.

I am unaware of any cases of a catastrophe being avoided because someone acted on their prophetic dream to stop the disaster occurring.

The second way, which is essentially the same as the first: wait. It's a bit like the first, but in this case you have a dream in which you are convinced that a life altering situation is going to happen.

Let's say you have a vivid dream of some life changing event happening when you are 32 years old. Maybe this will be a good thing - you will meet the partner of your dreams. Maybe it's a bad thing and you will die.

You have this dream as a child, and you really remember it, you're convinced that you have had a prediction of the future. Your life carries on, and you hand to 32 as a special number. You've primed yourself already for spotting things that happen based around this number.

Maybe you marry the partner of your dreams, but you're actually 29. However, you don't think any less of your premonition - it turns out you were spot on, because he lived at number 66 when you first me, which, is 32 x 3. You got married three years before you were 32, and that's a hit for your premonition!

Maybe you marry the partner of your dreams, but you're actually 29. However, you don't think any less of your premonition - it turns out you were spot on, because if you add the day, month and year of when you get married it's 23, which is 32 backwards! Granted it's 3 years earlier than you thought, but 32 is there if you look closely enough.

Of course, maybe the prophecy was your death, and you are convinced that you will meet your end at 32. However, you're in the 32nd week of your pregnancy, it's not been going well, and now, the 32 years has become 32 weeks, and the impending doom has transferred from yourself to your unborn child. Harrowing stuff, and entirely understandable. However, had these issues arisen in the 34th week you may not have thought anything of it.

It's a lot like the "27 club" - whereby famous and talented muscians die too soon, at the age of 27 - Amy Winehouse being a recent example, who joins the likes of Kurt Cobain, Jimi Hendrix,  and Jim Morrison. Of course, this club becomes self selecting. Any musician who dies at 27 enters it.

Nobody thought of the 27 club this year when we sadly lost David Bowie, Glenn Frey or the tragic deaths of Viola Beach reported today.

As soon as you become fixated on a particular feature of a dream, it is bound to crop up at some point in your life. Of course, this is not because your dream was prophetic. The details of the dream have long been forgotten, and all that is left is a fixation on a particular feature or two.

Again, from Paranormality Wiseman writes that sleep scientists are finding out that the majority of dreams tend to be unpleasant ones. This means that most "prophetic" dreams will involve something horrid.

None of these dreams, of course, translates to the real world, unless you make them, after the event, and with a little tweaking along the way.

If you're worried about your dreams, that's understandable, they can impact on how you feel.

But dreams are no more prophetic than tea leaves - you'll only see what you want to see. This is why it's best to forget your prophetic dreams- after all, they're more likely to be horrid than not, and who wants to see that?


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