Bad Science: The Low Fat vs Low Carb Debate

The diabetes establishment just can't get their head around the idea that cutting carbs helps people with diabetes. You can see this in the way the most recent study comparing low carb and low fat diets reports its results.

This was a metastudy just published in Diabetes Care.

Influence of Fat and Carbohydrate Proportions on the Metabolic Profile in Patients With Type 2 Diabetes: A Meta-Analysis Satoru Kodama, et al. Diabetes Care 32:959-965, 2009

Let's cut to the chase. This study which is a metastudy, glommed together the findings of 19 previous studies and concluded:

the L[ow]F[fat]H[high]C[carb] diet significantly increased fasting insulin and triglycerides by 8% (P = 0.02) and 13% (P < 0.001), respectively, and lowered HDL cholesterol by 6% (P < 0.001) compared with the HFLC diet.

Translated into English this says that when you feed low fat diets to people with diabetes, their insulin levels (if they make insulin) rise, because the high carb intake has pushed up their blood sugar, their triglycerides--the blood lipid most closely associated with heart attack--rises and their HDL, good cholesterol, drops.

Pretty straightforward. But wait. That's not all they report, because the first sentence in their results section is this: Changes in values for A1C, fasting plasma glucose (FPG), and total and LDL cholesterol did not differ significantly between the LFHC and HFLC groups.

So what they're saying is that it makes no difference in the blood sugars of people with Type 2 diabetes whether they eat a low carb or high carb diet.

And here's the punchline: the final conclusion of this study is;

However, stratified analysis indicated that the increase in triglycerides was insignificant when accompanied by energy intake restriction" and "the adverse effect on triglycerides from the LFHC diet could be avoided by restricting energy intake to a degree sufficient for the attainment of weight reduction.

This translates to, "People with diabetes should continue to eat a low fat/high carb diet. They should just eat even less calories so they lose weight."

We could debate whether people with type 2 diabetes will lose weight on any diet that increases their insulin resistance, but that's not what I'm going to do here.

Instead, I'm going to show you the glaring error in this study that makes it irrelevant to its subject. And what is that? It's the definition of "low carbohydrate." Because it turns out that the "low carbohydrate" diet being compared to the high carb diet is one made up of 40% carb 40% fat and 20% protein.

Working this out against the daily input for a typical women, 2000 calories, we find that 800 calories would be contributed by carbohydrate. Since each gram of carbohydrate contains 4 calories, this means that the "low carbohydrate diet" being discussed here--the "low carb" diet explored in 19 studies--contains 200 grams a day of carbohydrate.

Can anyone not obsessed with the need to prove the worth of the low fat diet honestly argue that a woman with Type 2 diabetes who is eating 200 grams of carbohydrate a day is eating a low carb diet?

No wonder these people with diabetes saw no difference in their A1cs. They were eating twice as much carbohydrate as even the most flexible low carb dieter would consider low carb.

And the actual carb intake here probably was worse, because these weren't normal sized women. They were people with Type 2 diabetes, most of whom were overweight who were probably eating a lot more calories than 2,000. So their actual carbohydrate intake may have been as much as 300 grams a day.

How idiotic research papers like this get through peer review escapes me. Whatever your scientifico-religious beliefs, you'd think if someone is going to use the term "low carbohydrate" in your title and conclusions, they should be describing people eating low carbohydrate diets.

A diet that is 40% carbohydrates is not a low carb diet. A low carb diet is one that ranges from 7-20% of calories coming from carbohydrates and for that woman eating 2,000 calories it would top out at 100g a day of carb.

Try that diet, and you WILL see dramatic differences in A1c.

Just this week I received another email from a happy visitor to my web site reporting this:

My A1C at dx was 10.9%, (Dec. 4, 2008). As of May 4, it was 5.2%. Mainly low carb diet and exercise , plus metformin. Surprisingly, to me, quite mild exercise.

There is no drug on the market that will make that kind of improvement in the blood sugar of a person eating a high carb diet.

But the powers that be in the diabetes establishment continue to waste paper and electrons disseminating garbage studies like the one cited above. And because they do, and because doctors only pay attention to the conclusion, not the methodology, hundreds of thousands of people with diabetes are seeing their kidneys fail, their feet succumb to gangrene, and their hearts stop.

This isn't an abstract philosophical debate. It's a matter of life and death. The American Diabetes Association who fund the journal Diabetes Care are largely funded by junk food companies (Cheerios anyone?) and the drug manufacturers whose profits will fall if the diabetes community ever discovers the power of low carb diets to control their blood sugars.

Shame on them.