If you take two overweight people with metabolic syndrome (at increased risk for diabetes), give them the same number of calories, except one eats a high-protein diet, the other eats a lower-protein diet with more carbs and fiber, which one will experience better insulin sensitivity?
This new study out of Germany did just that and found:1
"Insulin sensitivity was 25% higher* after 6 weeks of the high-cereal-fiber diet than after 6 weeks of the high-protein diet."Group assignment:
* Measured by euglycemic-hyperinsulinemic clamp
- The high-protein group was eating 28% protein, 43% carbohydrate, and 13 g cereal fiber.
- The lower-protein, higher-carb, higher-fiber group was eating 17% protein, 52% carbohydrate, 43 g cereal fiber.
- This high-protein diet provided about 140 g protein and 215 g carb.
- This lower-protein/higher-fiber diet provided about 85 g protein, 260 g carb.
"High-protein intake was associated with a tendency to increased protein expression in adipose tissue of the translation initiation factor serine-kinase-6-1, which is known to mediate amino acid–induced insulin resistance."Anecdotally, I've noticed that people who eat more meat, and so more protein and fat, have a harder time clearing glucose from their blood.
This isn't the first time fiber was found to improve insulin sensitivity. This study found:2
"Increased insoluble dietary fiber intake* for 3 days significantly improved whole-body insulin sensitivity. These data suggest a potential mechanism linking cereal fiber intake and reduced risk of type 2 diabetes."A take-away message for me ... keep fiber intake up; watch protein/meat intake.
* 31 grams insoluble fiber daily. (Wheat bran is about 90% insoluble, where as oat bran is only about 50-60% insoluble)
2 Cereal Fiber Improves Whole-Body Insulin Sensitivity In Overweight And Obese Women, Diabetes Care, 2006