Saturday, April 25, 2020

Insulin Sensitivity in the Brain

We all know people who go on a diet, lose weight, and manage to keep it off. Others go on a similar diet, lose a little weight, and then regain it all, often ending up heavier than when they started.

Many people would say the latter group probably didn't follow the diet carefully and gradually ate more and more of the things they shouldn't eat.

But now there's some evidence that insulin resistance in the brain can predict weight-loss and weight-gain patterns. A German research group showed that people with insulin resistance in the brain lost less weight than people who were insulin sensitive and then regained the weight, whereas the insulin-sensitive ones were able to keep the weight off.

Apparently, the insulin sensitivity in the brain also determines where fat will be deposited. Those with brain insulin resistance deposited more fat in the visceral area, and this fat is supposed to be more detrimental than subcutaneous fat.

So what can we do with this information? At this time, not much. I don't know about you, but I'm not keen on injecting insulin into my brain.

However, knowing about this effect may help if you're one of the people who doesn't lose much weight even though you're following a diet strictly. When that happens, many health people probably blame you, assuming you're cheating on the diet even though you say you're not.

I know that kind of disbelief by medical people. My endo put me on an ACE inhibitor, which is usually used to lower blood pressure, because she said it would protect the kidneys, and people with diabetes are at risk of kidney disease. When other medical people see I'm on an ACE inhibitor, they ask how long I've had high blood pressure. I say I don't have high blood pressure, and they give me a patronizing look. At that point, I probably do have high blood pressure because I don't like not being believed.

Determining whether or not you have insulin resistance in the brain is not simple. The researchers used magnetoencephalography and functional MRI, techniques not available at your doctor's office.

Presumably, anything that reduces insulin resistance elsewhere in the body should also reduce it in the brain, and that would include exercising and losing weight, things we mostly likely already know we should do.

But if you're still having trouble losing weight, it could be it's not a lack of willpower. It could be insulin resistance in your brain.


  1. You have probably already considered this but if not...

    Intranasal Insulin Reduces Body Fat in Men but not in
    Manfred Hallschmid,1 Christian Benedict,1 Bernd Schultes,2 Horst-Lorenz Fehm,2 Jan Born,1 and
    Werner Kern2
    Insulin acts in the central nervous system to reduce
    food intake and body weight and is considered a major
    adiposity signal. After intranasal administration, insulin enters the cerebrospinal fluid compartment and
    alters brain functions in the absence of substantial
    absorption into the blood stream. Here we report the
    effects of 8 weeks of intranasal administration of insulin (4 40 IU/day) or placebo to two groups of healthy
    human subjects (12 men and 8 women in each group).
    The insulin-treated men lost 1.28 kg body wt and 1.38 kg
    of body fat, and their waist circumference decreased by
    1.63 cm. Plasma leptin levels dropped by an average of
    27%. In contrast, the insulin-treated women did not lose
    body fat and gained 1.04 kg body wt due to a rise in
    extracellular water. Our results provide a strong, first
    confirmation in humans that insulin acts as a negative
    feedback signal in the regulation of adiposity and point
    to a differential sensitivity to the catabolic effects of
    insulin based on sex. Diabetes 53:3024 –3029, 2004

  2. Thanks. Intranasal insulin is interesting. It also seems to work with Alzheimer's disease (see Suzanne Crafts).

    The interesting thing about this study is that it works in men but not women, although the numbers were small and this might not hold up in larger studies.

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