Insulin Sensitivity Means More Than You Think

Insulin is, by current accounts, the greatest scourge to a lean physique, long-term health, smart children, world peace, sexual competence, NAFTA, singularity, the economy, the rain forests, climate change, your mother, your father, and your brothers and sisters. In short,  you should panic and throw yourself from the nearest window.  Since the nearest window is on the first floor, I merely got a bit wet (it’s been raining). Hopefully you smacked your head and came to your senses: we have insulin for a reason. Today, I’d like to shine the light on a study that shows we might be able to determine our “best” diet from our fasting insulin levels.In the study “Insulin sensitivity determines the effectiveness of dietary macronutrient composition on weight loss in obese women,” subjects were given a diet based on their fasting insulin levels. Those who were insulin-sensitivity (fasting insulin < 10 microU/mL) were given a high carbohydrate/low fat diet (60%cho/20%fat, HF/LF). Those who were insulin-resistant (fasting insulin > 15 microU/mL) were given a “low” carbohydrate/high fat diet (40%cho/40%fat, LC/HF). I put low in parenthesis because I don’t think 40% of calories from carbs is particularly low, though certainly lower than what one would see in the Standard American Diet…which is shit to begin with. Conclusion?

RESULTS: Insulin-sensitive women on the HC/LF diet lost 13.5 +/- 1.2% (p < 0.001) of their initial BW, whereas those on the LC/HF diet lost 6.8 +/- 1.2% (p < 0.001; p < 0.002 between the groups). In contrast, among the insulin-resistant women, those on the LC/HF diet lost 13.4 +/- 1.3% (p < 0.001) of their initial BW as compared with 8.5 +/- 1.4% (p < 0.001) lost by those on the HC/LF diet (p < 0.04 between two groups). These differences could not be explained by changes in resting metabolic rate, activity, or intake. Overall, changes in Si were associated with the degree of weight loss (r = -0.57, p < 0.05).

Those who could tolerate higher carbs got better results eating higher carbs. Those who couldn’t tolerate higher carbs got better results eating lower carbs. Excuse me while I pass out from total and utter shock…ok, now that I’m awake what the hell do we know? Well, this study was very unique in that all of the meals were prepared in the lab for the subjects and there were weekly weigh-ins and dietary compliance discussions. Quite controlled and I think it shows just how placing a blanket statement about any macronutrient is short-sighted, or in this case, misinformed.

So what’s the take home?

  • Pay attention to your fasting insulin level during your next blood test. If you’re not happy with your physique, make some adjustments.
  • This doesn’t mean that, if you’re insulin sensitive, you should eat high carb junk. EAT REAL FOOD, but now you can make more of those sweet potato fries you’ve been jonesin’ for. Health is still paramount.
  • If you’re making a change, pay attention to how your body feels; you might be insulin sensitive but still subjectively feel better on lower carbs. Trial and error here will go a long way toward better health.
  • There is no universally applicable carbohydrate level for all humans, full stop.

Insulin sensitivity determines the effectiveness of dietary macronutrient composition on weight loss in obese women.

5 thoughts on “Insulin Sensitivity Means More Than You Think

  1. Thanks for the effort, Skyler.

    This is such a small study that the results mean next to nothing, to me. And they tell us nothing about the situation in men. I’d consider it a pilot study needing clarification by a larger number of subjects.

    It does suggest why some people respond to one kind of diet and not another.

    There may be 5-10 common physiologic mechanisms leading to overweight and obesity. The optimal approach to weight loss could depend on the individual’s specific physiology.

    It’s too early to suggest checking insulin levels on everyone who wants to lose weigth.


    1. Hello Steve,

      There certainly wasn’t an attempt at portraying any diet or methodology as superior. Merely that there is mounting data to show ahead of time how (or rather how well) are person will do on X diet.

      I find this especially relevant for everyone that the study was done on obese women, as their bodies tend to fight back harder/lose fat more slowly than men. This of course doesn’t take into account leaner individuals but that’s typically not of concern for dietary research regarding using markers to guide dietary choices.

      I’m looking forward to seeing research in coming years with regards to further accumulating data, especially those that measure postprandial insulin secretion.


  2. Actually, this is something I discovered just this very week!

    I’ve been following the primal/paleo way of eating now for a year, but nothing was really working for weight loss, so I decided to go VLC and eat nothing but meat as much as I could. I didn’t lose much weight, a kilo or two, but I felt frackin’ AWESOME. I had energy, my mood was always light and stable, I was never hungry. I ate this way for about 9 months and all of a sudden this week I’ve been craving veggies like a crazy woman and I’ve been eating them like a crazy woman too. My carbs have gone up from 20g a day to somewhere more in the 50-100g a day but the weight’s falling off me now.

    Basically I think it took nearly a year of protein and fat to fix my insulin sensitivity and nutrition issues (4 years of a low-protein, high-grain, vegetarian diet) then my body went “You know what, I’m finally fixed. Lets work on getting some of this fat off, I don’t need it anymore!”


    It’s taken me this long though to realise it doesn’t matter what any experts say, or even those fluent in paleo ways – no one but you can ever know how much of anything you need. My body told me what it needed (first more meat, now more carbs) and I listened. No one else can listen to your body for you!

    1. Great work Natalie!

      “Nobody can listen to your body for you!” – The strangest thing is that it takes work to learn how to listen to cues subtler than “this food made me nauseous.” Of course, as a person loses fat, they tend to improve insulin sensitivity; I believe Richard over at Free The Animal has noted this as well.

      Again, great work!

  3. Agreed 100% that we all got to listen to our body. I however think that people just don’t get how long it takes or even how to do it at all. I think that many people think that a single experience is representative of an absolute root cause, failing to acknowledge the context (eg: sitting around all day vs just after a workout).

    On the second point though, I think some personalities, especially those over-analytical types, find it very hard to chase the vague notion of “listening to your body”.

    Then there are those on the opposite side, to whom food is simply a part of life, not worth a second thought. Eating becomes a subconscious process, and when they diet, they just listen to any “authority” who has given them some short term results (think low carb + water loss) and then take their advice is the bible from then on.

    Sry for the long and rambling post, but I hope it makes a point. Keep up the great work!

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