T Nation

Insulin sensitivity, wait a minute

Ok ok, did I read correctly?. In Doug Kalman’s article he states that low carb diets Improve Insulin sensitivity?. JB whats up with dat? Just confused now.Thanks Mike

The problem with ketogenic diets isn’t that they’re low in carbs but that they’re high in saturated fat.Most keto diets are high in saturated fat which is known to impair insulin sensitivity but Jeff Volek’s study participants ate a diet high in poly and monosaturated fats which improve sensitivity and thus the discrepency.Thats my guess.

In response to your “whats up with dat” question, I have a few comments:

1) There is conflicting data on every topic known to mankind. Take anabolics for example. You will find one study saying they dont work for every one saying they do. So if we changed our opinions each and every time a new study was published, we would be in real trouble...

2) With that said, I havent even seen the data so I wouldnt know how to comment. But I will say this, before I do see the data, Im still pretty sure that insulin sensitivity goes down with ketogenic diets.

3) The discrepancy may be the following (bear in mind I have only seen what Doug wrote on this site and that certainly isnt enough to form a solid opinion!)...Doug said specifically that the subjects lost fat and that insulin levels went down with the ketogenic diet. Well I agree that this will happen. Few carbs in the diet = low insulin. However low insulin in the blood doesnt mean high insulin sensitivity. In fact from the data Ive seen I believe that if these subjects were given a glucose challenge (some carbs), their insulin response would be much higher than in someone (healthy) who eats carbs regularly. This means that insulin sensitivity is impaired. Sure, it may not impact body comp when ON the ketogenic diet (as you will probably lose weight). But when coming OFF...look out!

4) Re-read my appetite safor construction article. I wanted people to understand that the danger of keto diets (with regard to insulin sensitivity) lies in coming off them.

Thank you very much John for taking the time to help me understand that better. Just jokin a bit with the wassup wit dat… me speaks proper english most of da time :slight_smile:

First of all, let me say that I have seen a
lot of conflicting data on this topic from
many sources. Some indicating the keto diets
increase insulin sensitivity and some
indicating a loss of sensitivity. I think this
is a case of “needs more research.”

But, let me point something out here. High *glucose* sensitivity does not = insulin insensitivity. In other words, if you give a glucose challenge test to someone on a keto diet, their body will react with a much higher insulin release than someone with more carbs in their diet. But this *does not* mean that their cells are insulin resistant. All that "extra" insulin may in fact be very effective at driving nutrients into cells. Such a scenario just means that the body is not used to seeing much glucose, and is therefore more sensitive to glucose, and *possibly* insulin also. And if you think about it, this makes sense because, on a keto diet, the body is "starved" for glucose, so it will want to make the best use of it by "sucking it all up into cells." Hence the greater amount of insulin to make best use of the available glucose. The problem when coming off a keto diet might arise because the body wants to "supercompensate" for that period of low glucose by storing lots of glucose, hence an increase in both muscle glycogen *and* adipose storage. In other words, the problem coming off a keto diet might not be due to insulin insensitivity but to "glucose supercompensation." Just a thought. I could be way off.

Free, thanks for clarifying the insulin and glucose sensitivity issues. For ease of discussion, Ive sort of lumped the two into one in the past (you’ve probably noticed this). It’s just easier on those not trained or familiar with science. Although the two are different, I think the functional consequences are the same. If you have poor glucose tolerance, you release a lot of insulin per unit glucose ingested even though you may not need it for nutrient uptake. And that can be a problem for fat gain. If you have poor insulin sensitivity, because the glucose doesnt get into the cells as easily, more insulin is released. And you get the same problem as above. Ideally you want the best of both (insulin and glucose tolerance) so that insulin stays low per unit carb in order to maximize the nutrient uptake in muscle while minimizing it in fat cells.

As far as your thoughts on the glucose situation on keto diets, I've recently seen data showing the hypoglycemia leads to low glucose uptake and insulin insensitivity in muscle tissues. It appears that since the body is glucose starved, it wants to preserve the glucose for brain function and other tissues and doesnt want the glucose to be all sucked up by muscle tissues.

Also during keto diets, the high blood levels of fats, the the reliance on beta oxidative pathways, and the ketones all also contribute to glucose and insulin intolerance. This situation mimics the syndrome x symptoms of type 2 diabetics who are obese and have cardiac problems.

I dont know how long this carb intolerance and insulin problem lasts after the keto diets are stopped but from what Ive seen, people get fat for a while after keto diets if not properly managed. This leads me to believe that the problem is a bit protracted.