Modelling energy intake (2): Corn oil

This post has been waiting around for some time so I thought I'd just put it up before settling down to read

The carbohydrate-insulin model: a physiological perspective on the obesity pandemic

but I'm also looking at

Food intake in diabetic rats: isolation of primary metabolic effects of fat feeding

Hyperphagia in Rats with Experimental Diabetes Mellitus:A Response to a Decreased Supply of Utilizable Fuels

and this one is pure Protons and ruminants

CALCIUM SOAPS OF FATTY ACIDS WITH VARYING UNSATURATION ASFAT SUPPLEMENTS FOR LACTATING COWS 

ditto this

Effect of supplementation with corn oil on postpartum ovarian activity, pregnancy rate, and serum concentration of progesterone and lipid metabolites in F1 (Bos taurus x Bos indicus) cows

and there might be at perhaps two more post on canagliflozin. Maybe.

When on earth I'll get to post on these I have no idea. Working on it!

Anyhoo. Back to today:

I thought it might be interesting to very, very crudely apply Kevin Hall's mathematic model to a much more interesting study. This one came my way via Jacob in comments quite a few weeks ago.

Response of body weight to a low carbohydrate, high fat diet in normal and obese subjects

This graph is an example of one single individual out of a total of five people in 1973, so we are talking about near-anecdotal data, but fascinating never the less.

The diet contained a fixed 168g/d of carbohydrate and 64g/d of protein plus a variable amount of fat over time. This is the weight change curve for subject "1", as far as I can make out:

This person lost around 2kg in the first 10 days on the diet then regained just a small amount over the following 25 days. For comparison if we now go on to look at Table 3 from Hall's

How Strongly Does Appetite Counter Weight Loss? Quantification of the Feedback Control of Human Energy Intake

we can see that a standard "lifestyle intervention" (Weight Watchers and exercise perhaps????) established an enforced caloric deficit of around 700kcal per day, which was eroded by hunger ("appetite") at something like an exponential rate, approaching the re establishment of baseline caloric intake with persistent ongoing hunger:

In the first month or so this caloric deficit triggered something around 2kg of weight loss. So if we took the graph for subject 1 at the top of the post we might reasonably assume an initial deficit of in the region of 700kcal with a rapid onset of hunger which would try to erode this weight loss effort. Something like:

Absolute CI decrease + CO increase = hunger, ie real life.

Except the subject in the graph at the top of the post was not in a weight loss study. He/she was in an overfeeding study. Carbohydrate and protein were kept fixed (and non-ketogenic) and progressively more fat was added to the diet, in steps, every five days. Here is the graph with the calorie intakes illustrated for this particular individual.

Yes, that is just under 6000kcal/d at a stable reduced weight.

Two things come to mind.

First is that it is stated that all subjects consuming over 2700kcal/d of fat felt warm all of the time and sweated easily. Second is that DLW measurement of TEE would certainly pick this up perfectly well and estimate a massive "calories out". Those would be as heat. Reversing-engineering weight loss to estimate changes in food intake is clearly completely out of its depth here. What happened?

The fat was corn oil.

Linoleic acid -> 4HNE -> activates uncoupling to blunt insulin signalling and causes insulin resistance per se -> hot, sweaty weight loss.

It takes a significant amount of linoleic acid to do this, well in excess of that needed to augment fat storage.

This effect appears to apply just as well to humans as it did to those mice in The ginger paradox (3), even when overfeeding is exogenously enforced. Clearly the mice which actively lost weight "effortlessly" (ie mice never do the human "appetite" battle unless they are exogenously semi-starved) on safflower oil used uncoupling to blunt insulin signalling and so increase lipolysis and adipocyte derived calorie supply.

Subject 1, on corn oil, had a peak of around 84% of calories from fat which put the linoleic acid percentage in the region of 40% of 6000kcal, well in to uncoupling levels. Corn oil in the 1970s was suggested to be around 45% LA.

Now, what would be expected to happen if we massively over fed with a lower LA, less uncoupling fat? The estimate for LA in olive oil in the 1970s was 7%. In this next graph the maximum LA percentage was 6% of calories, which is more akin to an obesogenic dose than to an uncoupling dose. Overfeeding olive oil does this:

That is 9kg weight gain in 40 days, and still going.

Now, what might we expect if we tried the same thing with beef fat? My expectations:

Weight gain would be even greater.

Metabolic syndrome would develop rapidly.

It should be much harder to sustain a 6000kcal diet of mostly beef fat than it was from either an uncoupling or  an obesogenic fat source.

The group didn't try overfeeding beef fat, sensibly.

There are a number of studies which I have picked up over the years which suggest that the uncoupling effect of double bonds kicks in at essentially all levels of their metabolism. At low levels the effect is over-ridden by the effect of failing to limit insulin signalling in adipocytes as per the Protons concept, leading to weight gain ie insulin still signals perfectly well and it does so more than is physiologically appropriate, especially in the immediate post prandial period. As uncoupling comes to predominate the ability of a low mitochondrial membrane potential to markedly suppress ROS generation becomes progressively more and more dominant, so insulin signalling becomes profoundly blunted. It will never get to high enough levels where insulin-induced insulin resistance should have kicked in, so the Protons concept becomes irrelevant. Under uncoupling, mitochondrial metabolism is functionally hypoinsulinaemic, it should resemble that of reduced insulin gene dose mice in Jim Johnson's lab where reduced insulin signalling was simply the end result of reduced insulin production, 24/7. It should also resemble ketogenic, hypoinsulinaemic eating.

Whether it is via 4-HNE/UCPs or 2, 4-dinitrophenol, high enough levels of uncoupling will absolutely blunt insulin signalling, with subsequent increase in access to adipocyte calories and consequentially suppressed hunger, leading to adipose tissue loss without increased food intake, with a few small caveats thrown in.

Peter