Thursday, June 28, 2012

20/20 Looked at Low Carb 10 Years Ago

It's incredible to think that this video from the TV magazine show 20/20 featured Taubes' then fairly revolutionary thinking on carbohydrates.  It was on July 7th, 2002, that his New York Times article, "What if it's all a big fat lie?" was published.  I remember reading afterwards that it was disastrous for bread sales.

Towards the end, Barbara Walters mentions that the Atkins Diet is a radical departure from conventional eating, and mentions that one can only eat "very little" in the way of vegetables.  I don't know where this is coming from, because Atkins most definitely emphasizes large quantities of non-starchy vegetables every day - more, in fact, than most people eat on the Standard American Diet.

I also don't feel that the way we eat is very extreme.   Many days, our meals resemble traditional homecooked meals, just without the bread, potatoes, rice or pasta.  And we skip the low-fat options too, so there's always a fair amount of cheese in the house, as well as cream and butter.

Be that as it may, I'm not a big fan of the Atkins diet.  To me, it allows too much prepared food and baked goods, which detracts from the whole food approach that I believe in.  However, I know it has worked for millions of people.  What do you think?  Take a look at the video and see for yourself:

Tuesday, June 12, 2012

Pasta-eating, beer-drinking Swedes and LCHF diets

A large new 25 year observational study from Sweden published in Nutrition Journal this month has found that Swedes started increasing their fat consumption from about 2004 onwards at the same time that low carbohydrate, high fat (LCHF) diets became popular.   This was a reversal of a trend towards lower fat options that started in the mid-1980's.

In addition to a distinct switch away from low fat margarine to butter, the following tables show a growing trend towards increased fat in the diet:

Far from losing weight as a result of the increased fat consumption (something the low carb community might expect), the body mass indexes (BMI) of the Swedes participating in the study continued to increase throughout the 25 year study period:

What was particularly worrisome to researchers was an apparent reversal in the long term downward trend of serum cholesterol levels starting around 2004, leading them to believe that Swedes were putting themselves at increasing risk of cardiovascular disease:

At this point you are probably thinking that this does not bode well for proponents of low carbohydrate eating.  After all, what could be clearer than the following trends away from carbohydrates in favour of fats?

As it happens, this study leaves me with more questions and skeptical observations than constructive conclusions:
  • While the percentage of energy from carbohydrates has been steadily falling in recent years, I would like to know whether the total calories consumed changed in this period, and if so, whether they increased or decreased.
  • On page 6, the study notes that there were 23 observations of BMI measurements under 10, and 3 above 100.  I don't know if any living person has ever had a BMI above 100.  Below 10 is also very unlikely.  One person was also recorded as measuring 2.7 meters (that's almost 9 feet!).  It's well known that the Swedes are some of the tallest people in the world, but that's rather extreme.  If the trained nurses who recorded these measurements made these 27 mistakes, I hope we can assume the others were more or less accurate.
  • This was an observational study.  There are many valid criticisms of observational studies drawn from self-reported questionnaires.  Portion sizes are notoriously variable, and people are often far from accurate in what they report that they eat.
  • It is very unfortunate that only total cholesterol was reported (it does not appear to have been measured).  Without knowing the subjects' triglyceride levels, or their HDL, the cholesterol trends in the table above are predictive of nothing. This must have been a terrifically expensive study, and it's a shameful waste not to have at least measured HDL.  
  • A very interesting chart shows that alcohol consumption showed a clear and steady upward trend.  In particular, men's consumption of export beer showed a steady increase that appeared to have had absolutely no correlation to the popularity of LCHF dieting.  Do you think those beer drinkers public realize what a carb-load beer provides?
  • On page 9 we read that consumption of boiled potatoes and whole grain crisp bread was balanced by consumption of pasta and whole grain soft bread during the 25 year study period.  It sounds to me as if carbohydrate consumption stayed relatively constant, even though they may now represent a smaller percentage of total food consumed.  In other words, I suspect total calories eaten increased even though this is not confirmed in the stufy.
So what do the results of this study mean?

I'm inclined to agree with the researchers that these Swedes might be at higher risk of cardiovascular disease than they might have been 10 or 15 years ago. This is probably because they are fatter than they used to be, and they appear to be eating more total calories than before because of an increased consumption of fats.  If they diminished their carbohydrate consumption at all, it probably wasn't by much, as consumption of potatoes and crispbread was replaced with bread and pasta, as well as more beer and wine, all rich carb sources.  However, because no detail was provided regarding the subjects' HDL and triglycerides, the rising cholesterol trend has little predictive power at all.

The wording of the study, and the resulting media headlines imply that LCHF diets lead to greater risk of cardiovascular disease.  However, there's probably no point at all in drawing any conclusions at all about the validity of low carb diets based on the results of this study, since the test subjects did not eat low carb diets.

Besides, just because LCHF started to become popular in the media around 2004, there's no proof that this has anything to do with any of the other apparent changes in trends.  Correlation does not necessarily mean causation.

While the subjects may have switched to HF, there's no indication of LC, in spite of what the headline might imply.

Oh well, I suppose the research funds helped to support the economy, at least.  But I would have preferred to have learned something useful and new from this study.

Edit:  It seems I'm in good company.  Denise Minger from Raw Food SOS shares many of the same thoughts on this Swedish study.  You can read her critique here.