Insulin: An Undeserved Bad Reputation, Part 3…MOOOOO!!!!

This article represents part 3 of a series on how insulin has been unfairly demonized by many in the nutrition field.  If you have yet to read the first few parts, you can read Part 1 here, and you can read Part 2 here.  In this article, I will discuss how dairy products are among the most insulinemic foods out there, yet do not promote fat or weight gain, which pokes holes in the hypothesis that carbohydrates drive fat accumulation through insulin secretion. 

Dairy Products Are Insulinemic Yet Don't Promote Weight Gain

One of the premises of individuals like Gary Taubes is that carbohydrates stimulate fat accumulation by stimulating insulin secretion.  I've already shown how this premise is flawed in the last two parts of my series.  Namely, I showed how protein also stimulates insulin secretion (sometimes as much as carbohydrate) yet does not promote weight or fat gain.  I also showed how the drug exenatide restores rapid-phase insulin secretion in diabetics yet promotes weight loss.

If the carbohydrate/insulin hypothesis were true, then we would predict that foods that are extremely insulinemic would be uniquely fat promoting.  What many people do not realize is that dairy foods are among the most insulinemic foods out there.  In fact, they create much greater insulinemic responses than you would expect based on their carbohydrate content.  Not only that, but lactose, the primary carbohydrate in dairy foods, is actually low glycemic and produces slow rises in blood sugar (lactose has a glycemic index of 46 compared to white bread which is 100).  In fact, the glycemic index of many dairy products is quite low, with full-fat milk at 39, skim milk at 37, ice cream at 51, and fruit yogurt at 41.

Despite the low blood sugar responses, dairy products create very large insulin responses.  For example, in one study, dairy products created similar or greater insulin responses than white bread, despite the fact that the blood sugar response for some of the dairy products was 60% lower than the white bread.  In this study, the researchers compared the glycemic and insulinemic responses between white bread, a low gluten/lactose mixture, a high gluten/lactose mixture, cod with added lactose, milk, whey protein with added lactose, and cheese with added lactose.  All of the conditions contained 25 grams of carbohydrate and 18.2 grams of protein, except for the white bread and low gluten/lactose mixtures, which contained 25 grams of carbohydrate and 2.8 grams of protein.  Thus, lactose was the carbohydrate in all of the conditions except for white bread.

When you look at the insulin area-under-the-curve (AUC) for the various conditions, you can see that the dairy products actually created greater insulin responses than the white bread, despite having similar amounts of carbohydrate:

Insulin response of dairy foods compared to white bread

It is obvious that it is not the lactose that is responsible for the greater insulin response, because the gluten/lactose and cod/lactose mixtures resulted in similar or lower insulin responses to white bread.

The blood sugar response was also not responsible for the greater insulin response.  In fact, the blood sugar response was lower in all of the conditions compared to the white bread, with the milk creating the lowest blood sugar response yet 3rd highest insulin response:

Blood glucose response to dairy foods compared to white bread

The insulinogenic index, which relates the amount of insulin secretion to the blood glucose response, was significantly higher in the dairy products, indicating that the dairy products stimulated much greater insulin secretion that you would expect based on the blood glucose response:

Insulinogenic index of dairy products compared to white bread

This is not the only study to show the insulinemic effects of dairy products.  I showed in my previous article how whey protein, a dairy protein, created the highest insulin response compared to non-dairy proteins.  In a study on type 2 diabetics, the inclusion of whey protein in a meal increased the insulin response by 31-57%, while the blood glucose response was reduced by up to 21%.  In another study, the addition of 400 mL of milk to a bread meal increased the insulin response by 65%, despite the fact there was no change in the blood glucose response.  In this same study, the addition of 200 or 400 mL of milk to a spaghetti meal increased the insulin response by 300%; again, there was no change in the blood glucose response.  In fact, drinking milk with the spaghetti meal created an insulin response that was similar to white bread.

Here's the results of another study showing the glycemic and insulinemic indexes of milk compared to white bread:

Why Does Dairy Stimulate So Much Damn Insulin?

It is clear that dairy products stimulate large amounts of insulin secretion, as much or more than white bread.  One of the reasons dairy products create large insulin responses is due to their amino acid content.  In fact, the postprandial insulin response from dairy products correlates with the rise in branched chain amino acids leucine, valine, and isoleucine.  I already pointed out in part 1 of this series how leucine will directly stimulate your pancreas to produce insulin.

Another reason that dairy products stimulate so much insulin secretion is their effects on a hormone called glucose-dependent insulinotropic polypeptide (GIP).  Like GLP-1 which I wrote about in part 2 of this series, GIP is an incretin.  This means that it is a hormone produced by your intestines that stimulates insulin secretion.  Dairy products stimulate increased production of GIP.  In the study I discussed earlier which compared whey, milk, and cheese to white bread, whey and cheese resulted in 21-67% greater GIP responses than white bread:

Glucose-dependent insulinotropic polypeptide (GIP) response to dairy foods compared to white bread

The above data illustrates one of the problems with the carbohydrate/insulin hypothesis...it assumes that carbohydrate is the primary stimulus of insulin secretion.  However, it is clear that amino acids and incretins play significant roles in insulin secretion as well.  And as I pointed out in part 1 of this series, the blood sugar response of a food only explains 23% of the variation in the insulin response.  Thus, a lot more goes into insulin secretion than the blood sugar response from eating carbohydrate.

Dairy and Weight Gain/Loss

It is clear that dairy products are extremely insulinemic, moreso than many high carbohydrate foods.  Thus, if the carbohydrate/insulin hypothesis were true, then we would predict that a diet high in dairy products should promote weight and fat gain.  However, studies fail to show any relationship between dairy product intake and weight gain.  For example, there is no relationship between intake of dairy products and BMI in Japanese women.  In U.S. men, there is no relationship between an increase in dairy consumption and long-term weight gain.  In perimenopausal women, high intakes of dairy products are actually inversely associated with weight gain (i.e, higher dairy product intakes are associated with less weight gain).

While these are observational studies, the results from controlled studies on animals and humans are similar.  In fact, animal studies show less weight gain when they are fed dairy products.  In mice, yogurt supplementation results in less weight and fat gain than controls on isocaloric diets.  In another study, transgenic mice lost weight on energy restricted diets.  The mice were then allowed to eat ad libitum (i.e., as much as they felt like).  The mice fed dairy products regained less fat and weight during refeeding.  In a third study, the intake of dairy products, but not a calcium supplement, decreased weight gain and body fat in mice fed a high-fat diet.  In a fourth study, dairy protein attenuated fat gain in rodents fed a high-fat, high-sugar diet.  In a fifth study, a dairy diet attenuated weekly weight gain in Sprague-Dawley rats.

Of course, these are animal studies.  What about humans?  In one study, low-fat dairy products did not promote weight gain, while high-fat dairy products did.  Hmmm, could it be that the weight gain in this study was simply caused by excess calories and not insulin?   In another study, increased intake of dairy products did not affect body composition.  In a third study, increased intake of dairy products did not impair weight loss.  In a one-year study, increased intake of dairy products did not affect changes in fat mass.  In a 6-month follow-up to this study, high dairy product intake predicted lower levels of fat mass.  In a 9-month study, increased intake of dairy products did not affect weight maintenance, but the high dairy group exhibited evidence of greater fat oxidation.

Why Am I Not Fat?

My own personal experience with dairy fits right in with the science.  I consume a lot of dairy and have for many years.  I go through 2-3 gallons of milk per week.  I also go through a lot of Greek yogurt, cottage cheese, regular cheese, and whey protein.  I have some type of dairy with just about every meal.   Thus, I have large amounts of insulin flowing through my body pretty much all day.  If insulin was truly the fat-promoting, weight-gaining hormone that some have made it out to be, then I should be obese by now.  Yet, I am not...not even close.

Not only that, but the people who think insulin makes you hungry, that would imply that I should be starving all of the time with all of the insulin that is flowing through my body all day.  Yet, I'm not.

Got Milk?  Got Insulin!

The evidence is overwhelming that dairy products do not promote weight gain, and they actually inhibit weight gain in animal studies.  This is despite the fact that dairy products produce very large insulin responses, as much or greater than many high carbohydrate foods.  Thus, it is clear from this article, as well as my previous articles, that the carbohydrate/insulin hypothesis is incorrect.  Insulin is not the criminal in the obesity epidemic; instead, it is an innocent bystander that has been wrongly accused through guilt by association.

Click here to read part 4 of my series, where I address the misconception of how insulin regulates blood sugar.

88
Leave a Reply

avatar
31 Comment threads
57 Thread replies
0 Followers
 
Most reacted comment
Hottest comment thread
33 Comment authors
MarkoJamielipo now funcionaMarty KendallWill Recent comment authors
  Subscribe  
Notify of
Todd
Guest
Todd

James, Good points about dairy being insulinogenic, and yet not fattening by itself. But I think you are missing something important here: Advocates of the carbohydrate/insulin hypothesis typically do not claim that insulin by itself induces fat storage; glucose must also be present. Taubes quotes Edgar Gordon on p. 392 of Good Calories, Bad Calories as follows: the storage of fast, and therefore the production and maintenance of obesity, cannot take place unless glucose is being metabolized. Since glucose cannot be used by most tissues without the presence of insulin, …obesity is impossible in the absence of adequate tissue concentrations… Read more »

Jason
Guest
Jason

There also might be an issue of the time horizon. What happens after one meal might not be indicative of what happens after years of exposure.

There have been several diet studies that have shown low-carb diets lower fasting insulin levels overtime better than low fat diets.

This is my favorite:
http://www.nutritionandmetabolism.com/content/3/1/7

Jennifer
Guest
Jennifer

Hi, I’m new to the site as well, but it looks like you have some interesting reading here and I look forward to delving into it. As for dairy and insulin, though, I don’t see where you can say that because dairy causes an insulin rise but weight gain does not (always) go along with it, that that proves that insulin is not the main culprit as far as fat gain. This makes sense in that the purpose of dairy is to grow immature animals to the stage where they can start getting enough nutrition on their own to become… Read more »

rmarie
Guest
rmarie

I’m new to your blog and this was a fascinating read for me. I have a very unscientific mind, so please excuse the following question which seems quite logical to me but may be way off: If whey or dairy ‘rev up’ insulin production while at the same time keeping BG low, would it help a pre-diabetic like me to consume some dairy along with carbs to help raise insulin to counter BG spikes? And I just have to ask this, James: Why are you consuming so much dairy – and low-fat at that! I would understand it if it… Read more »

Bryan - oz4caster
Guest

James, your excellent series has been a great revelation on the workings of insulin. I too am a dairy fan, but I use only raw Jersey milk with some made into kefir, plus some cheese (usually goat cheese lately). I’d be curious to see a post about your views on raw vs pasteurized/homogenized dairy and whole vs low-fat dairy (forgive me if you’ve already covered these topics since I’m new to your blog and haven’t looked at earlier posts yet).

Franck
Guest
Franck

“Why Am I Not Fat? My own personal experience with dairy fits right in with the science. I consume a lot of dairy and have for many years. I go through 2-3 gallons of milk per week. I also go through a lot of Greek yogurt, cottage cheese, regular cheese, and whey protein. I have some type of dairy with just about every meal. Thus, I have large amounts of insulin flowing through my body pretty much all day. If insulin was truly the fat-promoting, weight-gaining hormone that some have made it out to be, then I should be obese… Read more »

Lucas Tafur
Guest

Good post, James. I must say, nevertheless, that insulin is part of the problem, not the only one. Most trials showing the insulin response to a meal are just that, after 1 meal, in particular “healthy” individuals. You would expect that postprandial insulinemia after a calorie restricted diet high in carbohydrates or high protein/fat/LC would be practically the same (because as you imply, protein stimulates insulin as much as carbs). However, this is not the case. You know that insulin stimulation by protein/aminoacids is not equal as stimulation by carbs. The other issue is BG. While the insulin response can… Read more »

CarbSane
Guest

In my experience, dairy can be “fattening” in a low carb context, but not for the typical insulin (ir)rationale. Even if one is eating fatty meats, chicken with skin, bacon, etc., these foods tend to be self-limiting for most people. There are some people who may eat bacon grease or all of the drippings from a fatty burger, but animal fats and oils are not particularly palatable to most people. For example, I use 80-85% ground beef because I like the flavor and texture of the finished product. But if I’m browning it for a chili, I drain excess fat… Read more »

Sam
Guest
Sam

so much food for thought. I’ll avoid the puns for now. I really hope you’re angling all this work to be re-useable, angling toward ending up with something publish-able to compete against the pseudo science in the diet industry. For a long time I’ve been favoring the more expensive and horrid-tasting casein products over whey products, reasoning that casein’s slower-release protein would be better for hunger control, and partly this had to do with insulin control, (whey releasing more insulin, so preference goest to casein). This series on insulin is making me rethink my approach – the only argument left… Read more »

Jason Weber
Guest
Jason Weber

Krieger, you’ve done it again. You’ve completely thrown my head into a spin. Very nice and now I really understand more clearly the effect of carbs and diet. From what I gather, it’s not ingesting of carbs, but rather making sure I get the right amount of calories that are sustainable. Better carbs equals more satiety? More fats and better proteins to help the process? Very Nice! Thank you so much, because I am following a low carb diet but high amounts of protein and fats. My losses are due to calorie reduction and satiety, because I do feel full… Read more »

Giuseppe Meazza
Guest
Giuseppe Meazza

Mr. Krieger, First let me thank you for sharing such excellent content. It is a genuine honor to stop by and read your work. While I would still not make any sort of wild claims about promoting weight gain, per se, the fact that this series is on insulin did make me want to ask your general take on a somewhat related topic. With wide variation in individual sensitivities to various foods, and coupled with the often high stress nature of modern life (both beyond our control and oftentimes even more from self-imposed stress) is it possible that dysfunctional insulin… Read more »

1 2 3 4