High-Carb, Low-Fat Diet For Diabetes

If you downplay the contributions of fat and protein in the diet, the question becomes ... Can you eat a high-carbohydrate diet if you have diabetes? Yes. In fact, it may be easier to manage blood glucose when you're consuming a diet rich in minimally processed carbohydrates ... whole grains, beans, root vegetables, squashes, leafy greens, whole fruits.

That was the finding of this study:

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

Participants, all of whom had type 2 diabetes, were assigned to either a low-fat vegan diet or a conventional diabetes diet (using 2003 American Diabetes Association (ADA) Guidelines), which they followed for 22 weeks.¹

Here were each group's goals:

The high-carb, low-fat diet (HCLF): (~10% of energy from fat, 15% protein, and 75% carbohydrate) consisted of vegetables, fruits, grains, and legumes. Participants were asked to avoid animal products and added fats and to favor low–glycemic index foods such as beans and green vegetables. Portion sizes, energy intake, and carbohydrate intake were unrestricted.

The conventional diabetes diet: (15–20% protein, <7% saturated fat, 60–70% carbohydrate and monounsaturated fats, and cholesterol ≤200 mg/day) was individualized, based on body weight and plasma lipid concentrations.

Here's what participants ate over the course of 22 weeks (which did not quite meet their goals). Click to enlarge:*





* Not shown:
High-Carb Low-Fat Diet: Caloric intake 1425 kcal/day, Cholesterol 24 mg/day. Note that they did not eat a vegan diet.
ADA Diabetes Diet: Caloric intake 1392 kcal/day, Cholesterol 189 mg/day
________
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 HCLF group
  
• A1C fell 0.38 points in the ADA group

Reduction in diabetes medications:

• 43% of the HCLF group
  
• 26% of the ADA group

Body weight decreased:

• 6.5 kg [14.3 lbs] in the HCLF 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 HCLF group
  
• LDL cholesterol fell 10.7% in the ADA group

Reductions in urinary albumin:¹

• 15.9 mg/24h in the HCLF group
  
• 10.9 mg/24 h in the ADA group

Those on the high-carb, low-fat diet had lower blood sugars (and so could reduce their meds more), 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 HCLF group compared to the ADA group. 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.)

Gary Taubes in his book, Good Calories, Bad Calories said, "Carbohydrates make us fat and ultimately cause obesity. The fewer carbohydrates we consume, the leaner we will be." This study did not support his claims.

Participants in the HCLF 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. I agree with Taubes about one thing ... all calories are not alike.
________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.

Charts: Bix. Source: Data from study.