Tuesday, 20 March 2012

The Truth About Fat

After tackling some of the ideas around 'do more' in The Truth About Exercise, the BBC's Horizon program tackles some of the notions behind 'eat less' in The Truth About Fat (news release here),
  • Surgeon Gabriel Weston discovers the surprising truth about why so many people are piling on the pounds, and how to fight the fat epidemic.

    She discovers the hidden battles of hormones that control people's appetites, and sees the latest surgery that fundamentally changes what a patient wants to eat by altering how their brains work.Gabriel is shocked to find out that when it comes to being overweight, it is not always your fault you are fat.
The short, sharp summary is that Weston has discovered that obesity is not simply a matter of willpower, and there is evidence that it is heavily linked to genes, hormones and neurological factors.
A quick aside; to be honest it disappoints me that a surgeon - and in fact the majority of the medical establishment - are still so far behind the science curve when it comes to obesity.  'Fatty lacks willpower' is not the cause of obesity.  I mean much of what we see here was well known to me around 2007, and I was late to the paleo gig! 

The show kicks off with fat phobic inferences.  Weston assumes we crave fatty foods.  Hmmm - maybe, but to be honest it is sugary stuff that seems to enjoy ubiquity.  It is in your bread and chicken as well.  Sugar is also in your fat-free food. 

Weston also makes a classic error in stating that we have prehistoric genes which do not match up to a modern food-abundant environment, because food was scarce in prehistory.  Now head out in to the wilds.  Look at the animals.  Are they starving?  Nope.  Turn on your TV and tune in to a 'wild animal' program.  Are the wild animals perpetually starving?  Probably not.  I am not saying that there are not times of acute hunger-stress in the lives of wild animals, and exceptional climatic events will clearly lead to death from starvation, but for an adaptive species like ours, we're arguably the last to suffer. 

And that is the crux of the argument; if I were to take you out in to the wilds, you'd be dead of starvation in a few weeks.  You head out to the wilds with a survival expert like Ray Mears and you'll see that there is food all around.  Our HG ancestors were survival experts.  In an ancestral capacity, at the very least you can migrate with food in a geographical and temporal/seasonal fashion.  Furthermore, evidence suggests that the impact of drought and resulting episodes of hunger for example, affected those invested in settled agriculture more than HG.  For the record, we simply did not live in a perpetual state of hunger!  Calories were fugitive, not necessarily scarce.

Back to the program.  When Weston investigated hormonal influences on obesity she was asked to eat a breakfast of her choosing.  She chose a fry up.  Her bloods were taken and she was then asked to fast for 24hrs.  After the fast her bloods were again sampled.  Dr Carel Le Roux looked at two hormones (Ghrelin and PYY if I recall correctly) and plotted the concentration of each.  Categorising them euphemistically as a 'fullness hormone' and a 'hungerness hormone', Weston showed a standard profile of the former rising during a meal whilst the latter fell, and then in subsequent time, the signals from the 'hunger hormone' rising whilst the 'fullness hormone' level dropped.

In contrast, the obese seem to show almost a steady state level of each hormone so that they tend to graze continually, always peckish, without ever feeling full.  Signalling eh?  Who'da thunk it? (Contrast this grazing with an apex predator who hunts because of hormonal triggers relating to hunger).

What also interested me was that after her fast, Weston was told that she could eat what she wanted and she went for sugary pain au chocolat.  This, we were told was the fattiest and sugariest food available to her - but was it?  It may well have been the sugariest, but the fattiest on offer to her?  I am not so sure - and certainly Weston was not going to let fat-phobia ruin a good anecdote relating our 'love of fat'.

The program moved on to identical twins - and in particular, discordant twins.  Discordant twins are identical twins who are different in some particular way.  In this case the discordance was weight.  The driver for the discordance was EPIGENETICS!  The researcher involved seemed to think that stress was a major factor in genetic expression.  If he read De Vany then he'd have known this some time ago!

Other research covered the influence of RXRA expression, as driven by your mother's diet whilst in the womb.  Fascinating stuff.

The program closed with gastric bypass surgery.  What was interesting about this was how this surgery seems to affect appetite at a neuronal level.  Using MRI, psychologist Samantha Scholtz (yes she seems to have carb-chops), has shown how the reward and addiction centres of the brain react differently post gastric bypass.  The question is 'why'?  This is a work in progress (with the attendant suggestion of a 'pill' sometime in the future that mimics the effects).

All in all I welcome the publicising of much of this information, but a little bit of me was surprised that anyone in medicine should state that this stuff is new and revelatory.  It is rather damning that they are at least five years behind the curve and that some self educated monkey at his keyboard could have pointed them to evidence for much of this stuff a long time ago.

When the pupil is ready, the teacher arrives.

4 comments:

Chris said...

Your points are all very valid and well made. It was an interesting programme, but I kept thinking that we had heard all this before years ago....

Asclepius said...

I know the feeling. I can't wait to see the recommendation to IF which will no doubt feature in some future episode of Horizon...

Anonymous said...

I found the programme intersting but it left me hanging. What is to happen next is the real point of the programme with something of such groundbreaking diagnosis. We obviously cannot expect all overweight individuals to have bypass sergery carried out so how soon will the alternative be available. Is government in on the results and what is the health ministery doing to move things along. Like all matters concerning health of the nation time is of the essence.

Asclepius said...

Surgery is downstream of the problem. What the government need to do is to repeal their current support of bad advice - such as support of low fat food, support of highly processed food, financial support of the grain and sugar industries, be transparent about what we do and don't know when it comes to health advice, and, move with the science!