Nutrition is Complicated, Food is Easy

I had a few days off from eating normally while I was away. I’m one of those lucky people who doesn’t just tolerate but thrives on few dietary carbohydrates, so often my ‘normal eating’ is doing just that. I don’t put the diet on any sort of pedestal, it just works for me.

However, while out of town, I ate bread and maple syrup and yoghurt, I drank beer, I ate chips, and I didn’t feel the slightest twinge of anything except damn I am enjoying this food bc. it is nice. Up the Republic! Hooray for food! Pass the IPA, peasants!

I noticed something strange on my return, though.


My appetite was through the roof the first day back. Before dinner, I ate close to half a kilo of yoghurt, half a pound of blueberries, and a sandwich that was half a baguette with melted cheeses, ham, tomatoes and salad. And some nuts. And some more cheese. And I was hungry the whole time until dinner. Where I ate a lot more.

Today, my appetite is bludgeoned. Gone. I think it’s because I had my normal breakfast. Which is?

One small protein shake.

How truly exciting. How can man live with such largesse.

What gives?

Well, I say protein shake, but it’s more fat than anything else. After getting curious, I weighed one. The contents are:

35g cream

35g chocolate protein (Comeback)

35g 100% peanut butter

200g ice chips and water

Overall, it’s a hair over 30g of fat, 35g of protein, and stuff-all carbohydrates (maybe 5g?) which is over 65% fat by calories.

Like I said, it’s small. It’s also small by accident — this is just how much I ended up making for myself by trial and error. The fat content and temperature were actually two things I originally used to smooth out the taste of the acesulfame.

(Dairy products do this somewhat by themselves, and obviously my shake has dairy protein AND fats. The temperature thing also seems to help. Incidentally, some strong tastes seems to make good artificial sweetener masks — ginger, for instance, works well. And I’ve noticed that flavours which are supposed to have a bitter aftertaste, like tonic water, work well.)

But what’s the story with a high-fat breakfast? Why does it work for me?

Why is it so filling?

I had a quick look through the literature on appetite —it’s all over the place. As might be expected. It usually is.

For instance, this:

By the end of the day, the average total energy intake was significantly greater after the fat-rich EB meal than after the high-fibre, carbohydrate-rich meal (P < 0.05). Total day fat intakes were also significantly greater when the high-fat breakfasts were eaten.


But more recently:

Proportion of energy intake (%) in the morning meal was significantly and negatively associated with energy intake (kcal) in the subsequent afternoon and evening meals, and consequently in the whole day in both sexes. This significant and negative association was also observed for proportion of energy intake (%) of fat, but not of carbohydrate or protein, in both sexes.


Or perhaps it’s a protein + fat thing?

Participants showed increased satiety, less hunger and a lower desire to eat after the breakfast containing eggs relative to the cereal (p < 0.02), and croissant-based meals (p < 0.0001).


We could open this box a lot further (there’s a great deal of literature on protein and satiety!) but let me complicate things in a different direction instead…

Calories aren’t the only relevant descriptors of food, far from it. We need to consider the hedonic properties of what we’ve got here. Now, this shake ends up being very thick in its consistency, mainly due to the peanut butter I suppose.

At weekly intervals, 84 adults ingested 325-ml (220 kcal) shakes that were matched on weight, volume, temperature, energy, macronutrient content, energy density, rate of consumption, cognitive expectations, palatability, appearance, and requirements for mechanical processing, but varied in viscosity. …Significantly greater and more prolonged reductions of hunger were observed with the thicker shake.

Mattes and Rothacker

That in itself doesn’t really gel with the overall observation that liquid calories are, in general, less satisfying than the equivalent in solid calories.

The test foods included isocaloric, solid, and liquefied versions of identical foods high in protein, fat, or carbohydrate. Single beverage and no-load responses were also tested. … The beverage had the weakest satiety effect.


It’s hard to say whether or not this principle extends to really thick liquids.

The thickness is at least in part due to the presence of the ice (as opposed to water). An emulsion — crucial piece of kitchen science, this — is a mixture of two things which normally are mutually insoluble. Oil and water is obviously the most common one we see in the kitchen.

There are whole books written on the science of food emulsions, and formation is affected by temperature, pH, the relative concentrations of the fluids involved, shear force (the amount of force applied to the mixture when it’s combined) and the presence of any emulsifers (and this cream, interestingly, has those added to maintain its shelf-stable thickness).

Another factor — calcium. As a component of mouthfeel, calcium is really very interesting. This has recently been referred to as the recently-discovered “sixth taste”, when it turned out that sweet receptors on the tongue have a curious ‘additive’ responses to calcium compounds.

Recent studies have revealed that kokumi substances such as glutathione (GSH) are perceived through the calcium-sensing receptors (CaSRs) in humans… the addition of γ-Glu-Val-Gly significantly enhanced the intensities of thick flavour, aftertaste, and oiliness.


How much calcium is in my shake? Well, some. However, neither the peanut butter, the cream nor the protein state how much calcium there is in any of them.

So, somewhere between a tiny bit and quite a lot kokumi.

What a mess.

So far, we have:

a) the effect of the fat/protein

b) the creaminess or texture having a separate modification of satiety

c) the improvement of emulsification required for b) from the cold water

d) the avoidance of the ‘liquid calorie’ effect… or not?

d) the presence/absence of calcium as a modifier of sweet, salty and umami tastes present…

Now, here’s something else to consider: I trust my observations about as far as I can throw them. They don’t mean anything out of context.

I mean, what if it’s just me?

Is it a flavour association from licking the chocolate icing spoon as a child?

Is it my love of Trader Joe’s Dark Chocolate Peanut Butter Cups?


Moreover, how is my physiology different from yours?

Like I said at the start, my body is very happy with a low-carb diet. I don’t put it on any kind of pedestal (and it’s totally unsustainable if I’m doing high intensity activity) but in general I feel pretty good. But some people are RUINED by it. Be it physiology, cultural or lifestyle factors, some people just tolerate low-carb anything really poorly.

Artist’s impression of low-carbohydrate tolerance. Some artistic licence employed.

Shall we stop? Let’s stop and get to the good bit or we could be here all day.

We can dig into this problem endlessly. We can cover specific questions of food science, flavour perception, nutrition, and more. The total amount of factors to consider are many, caveats more still.

But none of it matters first thing tomorrow morning, when I will happily have another shake and start working, in complete and total ignorance of my blood sugar and ketone levels, relative satiety levels, daily calorie load, glycogen status, unaware of anything except …

… well, I like my shakes.

They make my life easier and taste nice. They’re cheap. They work.

That’s all I really need to know.

Nutrition is complicated.

Food is easy.

I write about science. We can probably be friends.

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