Is insulin sensitivity as important as we think?

[Johan]

http://www.ncbi.nlm.nih.gov/pubmed/1...ubmed_RVDocSum

The current study was initiated to determine whether insulin resistance and/or hyperinsulinemia affected the ability of obese individuals to lose weight in response to hypocaloric diets. Thirty-one obese, nondiabetic women, with values for body mass index ranging from 28.0-35.0 kg/m2, volunteered for this program. Resistance to insulin-mediated glucose disposal was assessed by determining their steady state plasma insulin and glucose concentration during the last 30 min of a 180-min infusion of somatostatin, insulin, and glucose. The total integrated insulin response to breakfast and lunch was also determined. After the baseline measurements, volunteers were placed on a hypocaloric diet calculated to lead to a minimum weekly loss of 1% of ideal body weight. Individuals who met the criteria after 30 days of dieting were defined as weight loss successes (n = 20) and continued on the diet for another 30 days. Individuals not meeting the criteria were designated as weight loss failures (n = 12) and were discharged from the study. There was a mean (+/-SEM) weight loss at 60 days of 9.2 +/- 0.4 kg in the 20 individuals defined as weight loss successes, but there was no correlation between weight loss and either steady state plasma glucose or the total integrated insulin response (r < 0.1; P > 0.83). Furthermore, using the same criteria to define insulin sensitivity and insulin resistance as those for therapeutic successes, the therapeutic failures comprised six insulin-sensitive and five insulin-resistant subjects. In summary, insulin-mediated glucose disposal varied widely in nondiabetic, obese women, and there was no relationship between baseline insulin resistance or total integrated insulin response and weight loss. It is concluded that the ability to lose weight on a calorie-restricted diet over a short time period does not vary in obese, healthy women as a function of insulin resistance or hyperinsulinemia.

[Johan]

Thoughts?

It seems to me that as long a supplement can't specifically increase insulin sensitivity in muscle tissue and instead increase insulin sensitivity everywhere, then it won't make much of a difference for fat loss?

[Johan]

bump

[Narkissos]

Originally Posted by Johan

Thoughts?

It seems to me that as long a supplement can't specifically increase insulin sensitivity in muscle tissue and instead increase insulin sensitivity everywhere, then it won't make much of a difference for fat loss?

What do you base this on?

That's a huge leap... particularly since the researchers did not distinguish between fat-loss and weight-loss here.

In fact, their conclusion definitely referenced 'weight-loss'.

I do not see this study having any relevance for our community or purpose... as each of us here is interested in body composition (i.e. fat-loss, lean muscle retention), as opposed to weight-loss.

But that's just my personal opinion

[Johan]

My reasoning is that the only reason(ignoring health benefits for the time being) we want to increase insulin sensitivity is to increase partitioning of nutrients to the muscles.

The only way to do that would be if we increase insulin sensitivity in muscle cells or decrease it in fat cells so that muscle cells get proportionally higher insulin sensitivity.

If we raise insulin sensitivity equally much in muscle tissue and fat, then we wont change at all how nutrients are partitioned. The body as a whole is a more efficient machine, but the same % of nutrients will go to the fat cells as before.

The study itself just made me thinking a bit. Would be interesting to see studies where they focus on body composition changes rather than weight loss.

[Narkissos]

Originally Posted by Johan

My reasoning is that the only reason(ignoring health benefits for the time being) we want to increase insulin sensitivity is to increase partitioning of nutrients to the muscles.

The only way to do that would be if we increase insulin sensitivity in muscle cells or decrease it in fat cells so that muscle cells get proportionally higher insulin sensitivity.

If we raise insulin sensitivity equally much in muscle tissue and fat, then we wont change at all how nutrients are partitioned. The body as a whole is a more efficient machine, but the same % of nutrients will go to the fat cells as before.

The study itself just made me thinking a bit. Would be interesting to see studies where they focus on body composition changes rather than weight loss.

Not sure if I agree with this totally. There's surely a weighted measure where sensitivity is concerned. I think muscle cells are more efficient at partitioning nutrients... so even if 'whole-body' sensitivity is increased 'equally', the ratio of the increased will be skewed towards partitioning nutrients towards musculature.

At least... IMHO.

'Cus I mean, I think about stuff like how many calories a pound of fat burns at rest, vs the amount of fat a pound of muscle burns at rest.

Sure...both weigh 1 lb. And, yes, both burn calories at rest. However, muscle burns way more than fat does.

Extrapolating, and applying the same actuality to nutrient partitioning, I don't think it'd be a stretch to suggest that equal points of increases (see: 1lb vs 1lb as measures) would not result in equal partitioning.