Obesity 2010, 28th Annual Scientific Meeting
"Lowering the Palmitic Acid Content of the Typical North American Diet Improved Insulin Sensitivity in Women"
Kien et al. found that replacing palmitic acid (a saturated fat, found in butter, cheese, beef, bacon, and palm oil which is in an untold number of packaged/processed snack foods) with oleic acid (a mono-unsaturated fat, found in olive, pecan, peanut oils) improved insulin sensitivity in young non-obese women.
It was a small study, just 18, but it was well-conducted - double-blind and cross-over. The high saturated fat diet increased insulin resistance in 8 of the 9 women. Insulin sensitivity improved by an average of 63% when women replaced saturated fat (palmitic acid) with monounsaturated fat (oleic acid).
They also found a decrease in VO2 peak in the saturated fat diet. VO2 peak is our maximum oxygen uptake (measured in volume, during exercise). It is now known to be an early marker of impaired insulin sensitivity.1 This low capacity for exercise, as measured by VO2 max, can occur even before other markers for diabetes such as impaired fasting and after-meal or postprandial glucose.
I wasn't surprised at the increase in sensitivity to insulin following a reduced saturated-fat diet (See Type Of Fat Eaten Affects Insulin Levels/KANWU Study), but I was surprised at the gender difference. I'll be keen to note male/female differences now.