Tuesday, June 19, 2012

Insulin, are you hungry?

An apology. This is a dry post, I had to edit the zombies out as it was getting way too long, maybe another day. It's a bit difficult to know where to start on quite how bad this paper is. Obviously, having read the abstract, we can flick down pretty well immediately to Fig 1 in the full text.



There are a few oddities. First is the flat line in weight gain on days 1, 2 and 3. This is the suppression of hunger by insulin, maybe. There was a full seven days on insulin. This I will return to in the next post.

Next is the sudden increase in weight gain through days 4, 5, 6 and 7 in the insulin infused groups, giving a final set of weight gains on day 7 which are not statistically distinguishable from controls. Except in the group on 2iu/24h of course. The group receiving 2iu/24h is special.

Then there are the data from days 11, 12, 13 and 14. By this time the insulin infusion had stopped (which occurred around day 7ish). Look at the 2iu/24h group. Waaaay after the insulin infusion had stopped their weight gain was still much slower per day than the other three groups. Oddly this didn't reach p < 0.05, despite standard errors which were far from overlapping those of the other three groups. But trying to see what the final weights gains were is difficult because these "post pump" weight gains have been, err, umm, sort of, err. I'm not sure what the word I need is...

You see the data from these last four time points are slightly moved. Each plot has been pulled down, and by a different amount each. No one is going to say by how much. It's pretty obvious that the control line can simply be moved back up to show a linear increase in weight from the insulin infusion period as these rats never got any insulin. But all lines have been shifted down so their day 11 values are set to their day 7 values, whatever the intermediate weight gain on days 8, 9 and 10 was. It is quite likely that the 6iu/24h and the 1iu/24h rats gained weight fairly linearly and so possibly ended up on day 14 at exactly the same weight as the control group. Or heavier.

It's also very likely that the 2iu/24h group also gained weight fairly linearly but slowly, ie their "pulling down" of day 11 values to those of day 7 didn't involve much of a drop compared to the other three groups. Who knows outside the lab?

Here are the data from Fig 1 in tabular form:




Anyhoo, the 2iu/24h rats, however much they did or didn't eat/gain on days 8, 9 and 10, only gained 1.39g/d on days 11, 12, 13,and 14. Food intake per day was down significantly through this later period, 27.7g/d vs at least 30g/d in all other groups. This is very important. The implication is that if you get yourself set up with just the right insulin infusion for a week, then you still won't be hungry a week later! Wow. Insulin is a satiety hormone blah blah blah.

But if you under-dose at 1iu/24h then it's, oh-oh, back up to pre-infusion weight gain rate, or possibly slightly more. Ditto if you over-dose at 6iu/24h, just the same thing happens. Fascinating. Do you think there might be something odd about this 2iu/24h group? Perhaps someone should repeat the experiment at this infusion rate? Then we might see if the result for these rats, on which the whole concept of suppression of weight gain over 7 days rests, was a quirk. No stats were done on the zero weight gain days, ie days 1-3 on insulin. The only p< 0.05, on which the title of the paper rests, was the 2iu/24h group at day seven.

If we lose the 2iu/24h group all we can say is that an insulin infusion reduces weight gain for three days, with complete restoration of any lost weight gain by the seventh day of a continuing infusion.


So, has the experiment been repeated? Luckily it has. By this very group. And the results are in this very same paper! But well buried. You have to be a dissonant pedant to find it. It's all in Figure 4.





This not quite the same experiment as Fig 1, the timings are slightly changed, but the basic design with insulin at 2iu/24h for seven days is identical.

In the main experiment time "on pump" was 7 days and they looked at all of these days, averaging everything over this time.

In Fig 4 they did the same 2iu/24h pump for seven days but only analysed days 3, 4 and 5 as time "on pump". Go figure. They also chose days 8, 9 and 10 as their "post pump" days vs days 11-14 in the first part of the study. Again, go figure. But eyeballing the graphical weight changes in Fig 1, I doubt this matters.

The data in Fig 4 look at meal size and meal frequency because that's how you bury data. But we can reverse engineer Fig 4 to get total food intake per day. Take a ruler to the graph. Multiply meal size by meal frequency and you get food intake per day, neat huh?

The rats on 2iu/24h ate 25.5g/d during "on pump" days 3, 4 and 5. This is pretty much the same as the total 7 day value from Fig 1 and Table 1. Happy researchers? Well done for correct choice of days. But...

Does the depressed food intake continue even after insulin has finished? Do you get sustained appetite control if you get the insulin infusion "just right" for a week? Eyeballing Fig 4's "post pump" values, these are about 3.4g/meal, 9.8 meals/day giving over 33g/d food intake...........

My, those are bloody hungry rats! This is the highest food intake per day in any group in the whole paper. It's the direct opposite of the findings presented in Fig 1 "off pump" section. The sustained depression of food intake shown in both Fig 1 and Table 1 could not be repeated in the Fig 4 experiment.

It doesn't happen.

The 2iu/24h group are no different to any other infusion rate when you look at Fig 4 "post pump" section. Quite why the rats on 2iu/24h used to generate Fig 1 data showed depressed weight gain long term is a complete mystery. Personally I'd want to have had a pathologist check out the pumps in the lowest food intake rats in this group, looking for low grade peritonitis. The pumps are in the abdominal cavity. Maybe some surgeon dribbled in to the wound during implantation. I've worked with surgeons. Ultimately we'll never know.

But ANYONE quoting the data presented of Fig 1 to you WITHOUT even mentioning the results of Fig 4 to you is, well, hmmmmm..... probably in obesity research.

I was going to go on to discuss the flat line of weight gain on days 1, 2 and 3 (at all insulin infusion rates) next but I'll leave that to another post as it has nothing to do with the "insulin at 2iu/24h causes sustained decreased food intake" claim.

Which is complete bollocks.

Peter

24 comments:

Sam Knox said...

Peter,

You may have already looked at this. It was in the "Related Citations " section of the webpage for the original study:

Effect of long-term insulin on body weight and food intake: Intravenous versus intraperitoneal routes
Christiane Larue-Achagiotis, Jacques Le Magnen
Laboratoire de Neurobiologie de la Nutrition, Coll├Ęge de France, Paris
Received 13 July 1984. Revised 17 January 1985.

The effects of continuous intravenous (i.v.) or intraperitoneal (i.p.) infusion of regular insulin on food intake (FI) and body weight (BW) were examined.

When rats were infused i.v. with insulin at 0·2 IU/h for 14 days, BW increased until the 10th day and then plateaued, whereas FI was augmented until the end of treatment. The 24-h hyperphagia was mainly due to a diurnal increase in FI—resulting mainly from a large augmentation in meal number, with unchanged meal size. Nocturnal meal number increased and meal size decreased so that nocturnal FI was not affected. At the cessation of infusion, rats became hypophagic and lost weight. Another group of animals, infused with a lower dose (0·1 IU/h), showed that the increases in BW and FI were dose-dependent.

Insulin infused (0·2 IU/h) for 14 days via an i.p. catheter increased FI and BW. The 24-h increase in FI was again mainly due to an enhanced diurnal intake, but at the cessation of insulin infusion rats did not lose BW. In rats infused with insulin at 0·1 IU/h for 14 days, BW and FI did not increase. In rats infused via an implanted minipump with insulin at 0·1 IU/h for 7 days, however, BW increased significantly over controls for the first 3 days, without any significant change in FI, the discrepancy between results observed here and other results is discussed, these effects suggest a relative ineffectiveness of the i.p. route compared to i.v.

Peter said...

Sam, yes, there is a world of difference between systemic and intra portal insulin infusions (though I'd not seen your citation). There are case reports of intense insulin resistance in humans on sc delivering pumps which eventually can be resolved by peritoneal pump delivery. I feel it is the systemic delivery needing massive inputs to get portal levels up to what they should be, with massive over exposure of adipocytes, which is the problem. ie systemic insulin causes far more insulin resistance via adipocytes than portal delivery... Though the paper is looking at very acute effects. Have to think about that one.

Of course this French paper completely disagrees with the findings on days 1-3 of the paper I've discussed. I don't think Vanderweele et al faked anything as the paper was so awful and the cover up so botched that they couldn't have faked anything this bad. Made up data and methods would easily have been much neater!

So reconciling the two is interesting. The French paper certainly rings true but we'd need to look at the fine print to see what was going on...

Peter

Bill said...

Wow, Pi-Sunyer is pretty big in obesity research (nowadays). I guess everybody's got to start somewhere.

Peter said...

Bill,

"Wow, Pi-Sunyer is pretty big in obesity research (nowadays)."

Which may go some way to explaining why the USA has the worst obesity problem in the world. One dreads to think what will happen when The Good Doctor gets in to power!

Peter

Michael said...

Please, leave this Good Doctor alone; he had/has better things to do than to properly supervise his underlings:

http://www.dailymail.co.uk/femail/article-1245397/Revealed-The-love-letter-writing-beauty-left-heart-bus.html

Elliot said...

Really enjoying all the great content lately.

I think Dr. Guyenet may be feeling the heat, as signs are he's changing his blog into more of a kitchen appliance focus... http://wholehealthsource.blogspot.com/2012/06/pressure-cooker-for-21st-century.html

Elliot said...

And to be fair, it does look like a nice pressure cooker...

Andrew S said...

as I understand it:

Rats get an insulin pump. In response, they develop some IR, cuz, gee that's a lot of insulin. Due to the chronic insulin level, they tend to eat more often to maintain a steady BG level and avoid both hypo- and hyperglycaemia. Total caloric intake doesn't charge, however. Maybe their body responds by producing less insulin.

Stop the insulin pump after a week. Cells can't get any nutrients because they're IR, and the pitiful amount of endogenous insulin just doesn't cut it. Hyperphagy sets in, and BG levels probably stay high.

Is that about right?

Bill said...

@ Michael, that is the most random thing I've ever read.

Peter said...

Micheal, !!!
Bill, yes!
Andrew, there are a few gems in the discussion which give more pointers as to exactly what is happening on days 1-3 but they are pure scandalous speculation rather than the hard data from Fig4. But cpd on soft tissue sarcomas tonight, so progress is slow...

Peter

Andrew S said...

There's some data hidden here by the 0 IU rats being the heaviest eaters before the test. The 2IU group post-pump had significantly different food intake post-pump compared to the other groups, but the difference from their pre-pump level is -2.2, compared to differences +1.1, +.3, and -0.8 -- was that significant, or did the authors hunt for anything they could stick an asterisk next to? The fact that group 2's post-pump weight gain was less than half of any other groups yet was not significant suggests that they're on the edge of statistical significance with all of these measurements anyway. Furthermore, in a set of 20 significant data points one expects one of them to be a false-positive (p = 0.05).

ie, interesting study. Either there's a bathtub curve here, or something went wrong with those 8+ rats, and the authors can only barely say that something is going on. Suggestive, but definitely needs to be repeated, with more rats and more levels. Yet on the repeat, they only used 4 animals?!

To base one's beliefs on the edge of significance for 8 rats seems unwise to me.

Chip Spitter said...

Hello Peter and others. I read this blog with great interest - which is why I’m apologising up front for what is probably a trivial anecdote (sorry, no rat studies to share).

Nutshell – after 4 months on LCHF my LDL-C has hit 12.9 (400), ApoB is 2.7. Compared with 5 years ago (typical low fat diet), these numbers have increased by about 250-300%. I’m Apo E4/E4 (boo). I know some here don’t place much importance on cholesterol numbers, and higher than average I could deal with - but those figures are insane. Call me a deluded narcissist, but it would seem I have some special issues to consider. My Trigs and HDL improved, it’s just the LDL that seem to dislike cream and sausages. No thyroid or blood sugar issues that I know of.

If anyone here has tips on where to look for relevant research or information, I’d greatly appreciate it. I’ll continue to research and monitor, but I figure if I (a dumb fisherman) throw it out in the pool where all the smart fish congregate, I may get a better response than " LDL 400? So what?"

Cheers.

Chip Spitter said...
This comment has been removed by the author.
Chip Spitter said...

Just to clarify - I understand from previous comments e.g.“Saturated fat and sdLDL?” that LDL is viewed as not being atherogenic. I guess what I’m asking is, does that opinion (or anything relating to CVD) change at unusually high levels of LDL particles – such as what happens for people with E4/E4 on a high sat fat diet?

If I'm being an idiot and you've already covered this, please tell me so. Thanks.

Suzie_B said...

Chip Spitter,
Have you tried researching at Lecturepad.org? This is a lipidology website. Requires free registration. I put APO 4E in their search and got 6 hits. There was at least one case history of an APO 4e patient with a prescribed treatment plan and another article explaining APO E stuff. You may also try Dr. Attia's site, http://eatingacademy.com/ and see if he can direct you to the information you need. He is very careful not to answer personal medical questions, but maybe he will tell you where to do your research. I'm sure there are more informed people that post here that could direct you better - I'm not a particularly smart fish.

Suzie_B said...

Chip Spitter,
Check out Jimmy Moore's podcast today (episode 585) with Dr. Dayspring. He talks about LDL particle numbers amongst other things lipid related - http://livinlavidalowcarb.com/blog/

Chip Spitter said...

Thanks Suzie_B. Yeah, I've had a brief look at lecture pad and have read some good stuff on ApoE. I am also familiar with Attia et al. First impressions are that they are very focused on particle count, with firm beliefs in LDL's ability to stuff you up good and proper. Which is why I threw it out here instead - I had a rough idea of what I'd get from Attia and Dayspring.

Sorry, I'm now in embarrassment mode for asking. I guess I'm still not over the shock of the numbers. I'll see that they are just numbers eventually. Have a good weekend.

Jane said...

Chip Spitter,
It has been suggested that the problem with E4 is to do with oxidative stress.

'Apolipoprotein E (apoE) has antioxidant activity at physiological levels, in the order E2>E3>E4, as was shown in cell cultures by Miyata and Smith.25 The antioxidant activity of apoE has been supported by studies in mice72,73 and the association of APOE4 with oxidative stress has been shown in AD [Alzheimer's Disease] patients..'
http://jmg.bmj.com/content/41/4/261.full

It sounds to me as if you have oxidative stress, possibly due to iron overload in your liver together with mild copper deficiency. Copper deficient animals have liver iron overload and raised cholesterol.

Saturated fat has been found to increase iron absorption and decrease copper absorption.

Let me know if you are interested to hear more. Hardly anybody knows about these things and I sometimes get abused if I try to tell people.

Dave Lull said...

"Answer Day: What Causes High LDL on Low-Carb Paleo?":

http://perfecthealthdiet.com/2011/03/answer-day-what-causes-high-ldl-on-low-carb-paleo/

Michael said...

Welcome, oh fellow member of the '400 Club'!

I guess I've become a little to good at metabolizing ketones for my immune system's good - I'll be upping my carb intake throughout the day, eating seaweed for iodine, largely replace ghee with tallow and wait for my next blood test results in a few weeks.

George Henderson said...

I'll pop this paper in here where it's sort-of-relevant.

I've always wondered, how is it possible that in hepatic IR states Fox01 activity results in BOTH gluconeogenesis and lipogenesis?

I mean, conservation of energy neither created nor however it goes?

This looks like providing some answers.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2712626/

"But the two abnormalities can hardly be subsumed under the common rubric of insulin resistance. For while it's increasingly clear—and strongly supported by the papers by Kubota et al. and Dong et al. in this issue (Kubota et al., 2008; Dong et al., 2008)—that an impairment of insulin receptor signaling to Foxo1 can explain insulin's inability to restrain HGP, one would predict that, if the liver were wholly insulin resistant, triglyceride (TG) synthesis and assembly into ApoB-containing lipoproteins would also be impaired. But the opposite is true in the diabetic liver.

In recent years, the idea that the diabetic liver may harbor a noxious brew of insulin resistance and excessive insulin sensitivity has gained a second wind. The concept is neither new nor limited to the liver. Several manifestations of insulin resistance—e.g., polycystic ovarian disease and acanthosis nigricans—reflect excessive rather than reduced insulin signaling."

mk07 said...
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Peter said...

Hi mk,

I think the simple answer is that I don't know. Some things are clear: 1. You are very insulin sensitive. 2. If you glucose spike on 10g of sugar I would presume you lack a first phase insulin response. 3. If you crash post (carb) based foods you clearly have second phase insulin response. 4. Second phase response is appropriate for the glucose spike but excessive for your whole body insulin sensitivity.

Over the years I have stubbornly failed to become fascinated by leptin, but anyone who has stopped cycling at 20 years old should be looking in this area... Are you skinny?

A 72 hour fast induces physiological insulin resistance. A ketogenic diet mimics that without the inconvenient (and eventually fatal) weight loss. But a ketogenic diet only does this if primarily based around highly saturated long chain fats. Not polyunsaturates and not medium chain fatty acids.

Ultimately, you have to ask: What do I want from my medical investigations? If you have a specific gene problem, ie you are a potential C57BL/6 mouse in human guise, you are not going to be able to get gene therapy to fix it and there is unlikely to be some miracle drug sitting there waiting for a medic to get an "Ah ha!" moment and reach for their prescription pad...

You have already worked out that two things help, starvation and meat/fat based eating. It is a simple fact that you can extend starvation indefinitely using a saturated fat based diet. Protein requires some insulin and the lower the better for its intake within the minimum needed for health, prob just under 1g/kg. Carbs at a level to mimic stored glycogen reserves, in very slow absorption forms, are non problematic and then it's just as much ruminant fat (most saturated) as needed to maintain bodyweight, which is essential.

This is pure pragmatism. It is not really a hardship, many of us in the LC community have eaten this way for years. I'm personally approaching 10 years. For myself the only reason to continue was that it completely eliminated my (clearly symptomatic) reactive hypoglycaemia. I was HUNGRY 2h post fast acting carbs, unlike yourself. Eventually I realised it also fixed a lot of other problems.

OK, so no answers other than how you might sidestep whatever the problem is...

Peter

mk07 said...
This comment has been removed by the author.