Saturday, February 02, 2013

It's The Fat In The Diet, Not The Carbohydrate, That Drives Diabetes

This is a fantastic video. It's a TED talk by Dr. Neal Barnard on how a very low fat diet, one that essentially excludes animal food, can in effect "cure" type 2 diabetes. What I love about it is his description of how insulin works to clear the blood of glucose, and how it is not so much the glucose in blood (or the sugar and starch we eat that gets converted to blood glucose) that drives diabetes, but the inability of insulin to assist entry of glucose into the cell, that is, insulin resistance:

The study to which he refers:

A Low-Fat Vegan Diet Improves Glycemic Control And Cardiovascular Risk Factors In A Randomized Clinical Trial In Individuals With Type 2 Diabetes, Diabetes Care, August 2006

Here's a discussion of this study from a few years ago: High-Carb, Low-Fat Diet For Diabetes.

Barnard compared his low-fat, vegan diet to the American Diabetes Association's diet. What happened when people with diabetes ate a high-carb, low-fat diet - consuming 70% of their calories as minimally-processed carbohydrates? They lowered their blood glucose. Here's how each group fared (all of the following were statistically significant):

Among participants whose diabetes medications remained unchanged: (A1C is short for hemoglobin A1c or HbA1c, a measure of blood glucose over the last 3 months.)
  • A1C fell 1.23 points in the Vegan group
  • A1C fell 0.38 points in the ADA group
Reduction in diabetes medications:
  • 43% of the Vegan group
  • 26% of the ADA group
Body weight decreased:
  • 6.5 kg [14.3 lbs] in the Vegan group
  • 3.1 kg [6.8 lbs] in the ADA group
Among those who did not change lipid-lowering medications:
  • LDL cholesterol fell 21.2% in the Vegan group
  • LDL cholesterol fell 10.7% in the ADA group
Reductions in urinary albumin:1
  • 15.9 mg/24h in the Vegan group
  • 10.9 mg/24 h in the ADA group

Those on a low-fat, vegan diet had lower blood glucose, lower LDL cholesterol, improved kidney function, and over double the weight loss. There were also significantly greater reductions in BMI, waist circumference, and total cholesterol in the low-fat group compared to the ADA group.

Notably, there was no significant difference in exercise between groups, so these changes weren't because vegans were overtly spending more calories. ("Overtly" is key, since, as previously discussed, some diets lead to greater expenditure of calories from digestion and thermogenesis.)

Participants in the low-fat, vegan group were allowed unrestricted consumption. They could eat as many calories and as much carbohydrate as they wanted, as long as they didn't eat from certain food groups. Participants in the conventional diet group had to limit their caloric intake, count calories, and control portion sizes. Even with unrestricted food intake and a higher calorie consumption, the high-carb group lost more than twice as much weight.

It is frustrating for me to hear people say their doctor instructed them to eat fewer carbohydrates since their blood glucose is inching up. I've researched this for years and I can see it's more the fat in the diet, not the carbohydrate, that is a problem. Also, fat is the ideal solvent for many industrial pollutants, chemicals which have been implicated in the development of diabetes, obesity, and other metabolic disorders. And these chemicals bioaccumulate, making the fat of animals - cheese, butter, lard, marbled steak - likely to contain the highest amounts.
1 People with diabetes suffer microvascular complications involving the kidneys which allow passage of protein into urine. The lower the amount of the protein albumin that leaks into the urine, the healthier the kidneys.


RB said...

I like the story about the ribs.

The more about learn about low-fat plant-centric diets, the more I think they are the way to eat.

Ezer said...

His examples are terrible, first we don't have carnivore teeth because we evolved to eat cooked meat and cooked food in general. We smaller intestine than gorilla's because of the same reason. He says we were bad hunters, but he doesn't realize humans probably practised persistent hunting that's very different from other animals.

Ezer said...

I wouldn't emphasize the absence of animal food in the diet. I'd emphasize consuming 70% of the calorie from minimally-processed carbohydrates. That means a lot of fruits and veggies, a lot of vitamins, antioxidants and very little carb (if he counted fiber as carb) and very slow digesting carbs. That means very little crap. That's what the study shows, his explanations about fat obstructing insulin being the cause is mere hunch.

Bix said...

I wouldn't call his point about dietary fat and insulin (and so, diabetes) a mere hunch. There is a lot of scientific support for this hypothesis:

Mitochondrial H2O2 emission and cellular redox state link excess fat intake to insulin resistance in both rodents and humans

Which I discussed here:

Diabetes Is A Disorder Of Fat Metabolism

Some more studies:

Dietary Fat And Diabetes

Dietary Fat Raises Insulin Levels

Type Of Fat Eaten Affects Insulin Levels

The More Fat You Eat, And The More Saturated That Fat, The Higher Your Risk For Diabetes