Tuesday, June 19, 2012

Does Dieting Increase Diabetes Risk?

That's certainly the message that HAES practitioner Linda Bacon wanted her followers to believe. In fact her tweet suggests that "even short periods of calorie restriction" increase diabetes risk.

In case you're not familiar with Dr. Bacon her work challenges the assumptions made about obesity and she has been highly critical of studies linking obesity with morbidity and mortality.

In an interview she gave to Med Journal Watch she explains why she believes not everyone agrees with her conclusions,

"My experience from having worked closely with many obesity researchers who are more conventionally-minded than me is that they are so strongly mired in their assumptions, that they don't look at the evidence."
And now back to diabetes and dieting, the story of which in this case begins back in time during the Dutch famine of World War II which they not so affectionately call the Hongerwinter (hunger winter).

It was September 1944. The Germans blockaded Holland and cut off food and fuel shipments to punish the Dutch people who opposed the Nazi regime. Food stocks dwindled. By the end of November rations amounted to fewer than 1,000 calories a day, and by February, to 580. 4.5 million people suffered, and over 22,000 perished. At the famine's worst daily rations amounted to half of a medium sized potato and 2 slices of bread. To compound matters, fuel was nearly impossible to come by and despite frigid winter temperatures, gas, heat and electricity were turned off. The famine lasted until May 1945.

Can you imagine being a child in Holland during the famine? The suffering and the horror they must have felt are unfathomable and when coupled with the severe and prolonged under-nutrition they experienced perhaps it's no surprise that their cohort have seen increases in risk of a variety of medical conditions including type 2 diabetes.  It's their experiences that Dr. Bacon uses as the source for her diabetes related caution against dieting.

The link Dr. Bacon provided in her assertive tweet about dieting and type 2 diabetes risk led to a a paper entitled, "Famine Exposure in the Young and the Risk of Type 2 Diabetes in Adulthood". In it researchers studied 7,557 Dutch women who endured the Hongerwinter and who on average were 9 years old when it occurred. Subjects were stratified into 3 groups on the basis of their self-reported exposure to famine - none, moderate and severe. The researchers found a small and statistically significant increase in risk to those women who reported themselves as moderately or severely affected by famine and this risk, while slightly attenuated, persisted after controlling for age at start of famine, education, BMI, waist circumference and waist to hip ratio.

The authors also noted that their study was unable to distinguish whether or not this association was related to under-nutrition or to famine related stress and point readers to a Finnish study that found a similar increase in lifetime risk of type 2 diabetes associating with the results of a psychological stress test in childhood war evacuees.

So in the end it would seem that from reading the evidence enduring a moderate to severe famine at a young age increases the risk of developing type 2 diabetes perhaps by way of the impact of under-nutrition, or perhaps by way of the impact of psychological stress, or perhaps by another as yet not elucidated cause.

In no way shape or form does this data suggest that "dieting" increases the risk of type 2 diabetes and in no way shape or form is suffering through a famine where daily rations include 2 small slices of bread and half a potato fairly described as a "short period of calorie restriction".

For Dr. Bacon this seems to be a bit of a pattern - slam conventional researchers for being, "so strongly mired in their assumptions that they don't look at the evidence", and then be so strongly mired in her assumptions that either she herself doesn't look at the evidence, or if she does her confirmation bias is so powerful that she'll happily find a way to present it to fit her narrative (click here for more examples). When I questioned her about this particular example on Twitter, despite her battle cry on Huffington Post of, "Show me the data we demand, and you should, too", she blocked me.

A few days ago dietitian and HAES advocate Julie Rochefort asked me on Twitter what barriers I saw to mobilizing HAES into practice. The main one I see seems to be regularly reflected by Dr. Bacon - knee jerk anger and either the willful manipulation of evidence, or a lack of critical appraisal of data so long as it seems to fit the HAES storyline.

Dr. Bacon is certainly HAES' most visible champion and role model. Responding to criticism with anger and manipulating or simply not critically evaluating HAES friendly data undermines the credibility of HAES as a whole, makes HAES easier for detractors to dismiss, and sets an absolutely terrible example for HAES practitioners and supporters to follow.

Annet van Abeelen, Sjoerd Elias, Patrick Bossuyt, Diederick Grobbee, Yvonne van der Schouw, Tessa Roseboom, & Cuno Uiterwaal (2012). Famine Exposure in the Young and the Risk of Type 2 Diabetes in Adulthood Diabetes DOI: 10.2337/db11-1559