WHI: Low Fat Diet Does NOT Decrease Incidence of Diabetes

The same folks whose multimillion dollar brought you solid evidence that the low fat diet does not reduce heart disease have just analyzed their data and found that eating a low fat diet has no impact on preventing diabetes.

Here's the study as reported by Archives of Internal Medicine:

http://archinte.ama-assn.org/cgi/content/short/168/14/1500

The Women's Health Initiative Study lasted 12 years and involved 48,835 postmenopausal women aged 50 to 79 years. Women were randomly assigned to a usual-diet comparison group (n = 29 294 [60.0%]) or an intervention group with a 20% low-fat dietary pattern with increased vegetables, fruits, and grains.

Here is the finding: "Weight loss occurred in the intervention group, with a difference between intervention and comparison groups of 1.9 kg [4 lbs] after 7.5 years (P < .001). Subgroup analysis suggested that greater decreases in percentage of energy from total fat reduced diabetes risk (P for trend = .04), which was not statistically significant after adjusting for weight loss." [emphasis mine]

What this means is that whatever tiny difference they found in the incidence of diabetes between the low fat diet group and the group eating a high carb, high fat "eat what you want" diet disappeared when they adjusted their data to take into account weight loss.

People who lost a bit of weight over this period had less diabetes, no matter how they lost the weight.

In fact, we know now that low carb diets produce more sustainable weight loss than do low fat diets. That has been shown in quite a few studies, the most recent of which is the Israeli study that found that a barely-low carb diet (one that was 40% carbohydrate, or 200 grams a day for a person eating 2000 calories a day) produced more weight loss than the low fat diet.

That study is reported here: http://content.nejm.org/cgi/content/full/359/3/229

So if weight loss alone heads off diabetes, the low carb diet would be a much better choice. Of course, the low carb diet (particularly one that is truly low carb, which is not really the case with this Israeli study) prevents diabetes not only by causing weight loss, but by lowering blood sugar to normal levels in people who are pre-diabetic, and by doing this, it prevents the glucose toxicity: the poisoning of beta cells by high post-meal blood sugars, which pushes pre- into actual diabetes.

Sadly, though, the hugely funded WHI study was designed by people who were so certain they would see huge gains from the low fat diet that they did not include an arm that examined other diet strategies. The WHI only compared the low fat/high carb diet with the high fat/high carb diet.

It is worth noting that the Israeli study did not find a significant impact on the development of diabetes in the group of mostly men they studied who were eating a Kosher 40% carb diet. This does not surprise me because these men were eating 200 grams of carbohydrate for each 2000 calories they consumed.

That works out to almost 60 grams per meal--equivalent to a bagel per meal--which would be enough to raise blood sugar damagingly high after every meal for anyone who had any impairment in blood sugar metabolism.

In fact, how this diet could be considered a "low carb" diet escapes me. I would not consider a diet to be low carb unless the carb intake was at most 20% of all calories, or 100 grams a day in a 2000 calorie a day diet, which feedback from a lot of people with diabetes who control their blood sugar using carbohydrate restriction suggests is close to the upward limit of carbs most people can eat and maintain control.

But still, you'd think that the fact that the WHI data show that the low fat diet had no impact on either heart disease or diabetes when compared to the "all crap all the time" typical diet would be the last nail in the coffin of the argument that people with diabetes should cut fat rather than carbs from their diet.

Sadly, it isn't. The American Heart Association and the American Diabetes Association and are funded almost entirely by the drug and device companies and medical groups who earn huge profits only as long people continue to have the diseases these organizations are supposed to be fighting. So as soon as they were published, the AHA denounced the findings of the Israeli study--as tepid as they were, despite the clear cut proof that study gave that the cardiovascular risk profile of people eating a barely low carb diet improved over 2 years compared to those eating the low fat diet.

The ADA is almost certain to ignore the WHI data and say that "more study needs to be done" though the fact is that this was the single largest study of nutrition and health ever funded.

In fact, you can already see how this latest WHI finding was either a) ignored or b) spun by the mainstream media who report it. I've seen at least one report (based on the same abstract you saw at the head of this post) that touted the statistically insignificant difference between the low fat and non-low fat groups as implying that the low fat diet prevented diabetes, when the words "statistically insignificant" mean that in fact the difference in diabetes incidence between the two groups is meaningless.