Reason for a New Age

Food & Diet

Posted by publius2point0 on 2014/03/10

At its heart, food has two purposes in the human body:

  1. Energy
  2. Material

If we think of it in the terms of a car, over its lifespan a car will need fuel (gasoline, electricity, etc.) and replacement parts as old ones wear out or break. The human body isn’t so much different from that, aside from a few quirks. Humans do grow (while still young), so the food we eat doesn’t always replace something old, and of course cars need someone on the outside to change out parts where the body can correct itself with no more needed than eating a well-rounded diet.

Of course, the big question is: What is a well-rounded diet?

Despite all of the thousands of debates and millions of books out there, this is actually a pretty easy question to answer if you just work back from the information given above. A well-rounded diet needs to provide the right amount of energy and the array of materials that the human body needs. It’s basically as simple as that.


Energy in food comes principally from (and I steal shamelessly from the Wikipedia) carbohydrates, fats, proteins, organic acids, polyols, and ethanol. Each of these are molecules of hydrogen and oxygen with the occasional carbon or nitrogen. Via the wide variety of metabolic pathways, these are converted into ATP (for use) or fat (for later use). ATP is composed of hydrogen, oxygen, nitrogen, and phosphorous. Fats (triglycerides) are composed of carbon, hydrogen, and oxygen.

Now I break this down to the atomic because, while molecules of H, O, N, C, and P aren’t fungible in the human body, as you might note from the chart of metabolic pathways in the above link, there are enough routes that can be taken to convert one molecular type into another type that so far as it goes when talking about “carbohydrates, fats, proteins, organic acids, polyols, and ethanol”, one might as well say that they are all equivalent to the body. At the end of the day, they’re going to be rent asunder into their component atoms and reassembled into whatever is needed. A few pathways are more indirect, so that some sources of energy are less efficient, but this is taken into account when calories are listed on food labels. You do not need to remember which types of energy are more or less efficient at growing your ass.

Interestingly, carbon is a component of fat but not of ATP. Unfortunately, I think you’re out of luck if you want to try to avoid eating carbon so that your body can’t create fat. But that is an interesting point about chemical reactions.

Chemical reactions follow a system similar to puzzles. If the ins-and-outs of two objects don’t align just right, then you’re just plain out of luck in terms of getting anything to happen between them. This is one reason why the general answer to questions like, “What happens if I eat a lump of plastic?”, are that you’re just going to poop it. Plastic molecules just don’t have the right shape to be noticed by any of the chemicals that your body is going to expose the things that you ingest, so it will be ignored. More interestingly – from the standpoint of diet – is that if your body lacks one chemical, then it might not be able to do something else. The citric acid cycle, for example, is one of the major metabolic pathways. It is the major route for carbohydrates, fats, and proteins to be turned into energy. But as the name suggests, the cycle is dependent on citric acid. Failure to ingest enough citric acid could, potentially, shut down the citric acid cycle and prevent your body from being able to convert food into energy. Unfortunately, the pathway to fat is completely different so all you would be doing is to decrease your activity level.

I should probably point out, at this point, that you should not try eating random chemicals – regardless of whether you think you’ll just poop them or not – nor should you arbitrarily try cutting out your supply of certain nutrients because you think you’ve spotted a way to shut down some particular subsystem of your body. Talk to a physician before putting or not putting something in your mouth.


Everything you ingest is, of course, a “material” for your body. But where food taken in as energy is largely burned and later exhaled, essential nutrients are used for structural purposes. You might note above that phosphorus is a component of ATP – which largely serves as the gasoline of the body – yet we don’t need to eat phosphorus to keep moving. I infer from that, that phosphorus is just a structural element of ATP and is re-used after all of the other elements are used. Minus it, you wouldn’t have any energy to do anything, but the rate at which phosphorus is lost from the body doesn’t have a strong relationship to how much energy you burn. (It looks like most of it forms the structure of your bones and teeth – along with other elements.)

For any essential nutrient, they fall into one of two piles:

1. Excesses will lead to toxicity.
2. Excesses will be pooped out.

But in all cases, if you don’t get enough then bad things happen. And so, if you read the tables listed in the page of Dietary Reference Intake, you can find out how much is too little (the Estimated Average Requirements) and how much is too much (the Upper Intake). For some things, like vitamin K, there isn’t any particular upper limit that we know of that you can intake with negative health effects. Not that I recommend verifying this, yourself.

Handily, there’s also a table of the recommended intake. Unfortunately, unless you enjoy memorizing lists, reverse engineering whether you’re hitting your targets from what you’ve eaten is not an easy task. Unlike energy, essential nutrients can’t be reduced to a single number (calories). Fortunately, if you’re not hitting your target, you’ll know it because you won’t feel healthy. So if you do feel healthy, then you’re eating all the nutrients that you need. If you’re not, then you’re either a hypochondriac (which is probably more likely than that you need to start taking multivitamins) or you should look through the tables and find things that you’re probably missing from your diet and see if you can add those to your diet – or talk to your doctor. But since almost everything we eat (the notable exceptions being salt and water) are former living creatures, and they have many of the same needs as us, by simple virtue that we’re eating our fellow life, it’s not too hard to get all the nutrients you need.

The Best Diet

So what’s the best diet?

Well, how much energy you burn in a day depends on how active you are and how efficiently you are able to move (e.g. men are generally larger, so there’s greater inertia for us to fight against when we move). There are probably ways to get a hard number, if you strap enough measuring equipment onto yourself and live your life as normal for a few weeks, but there’s an easier way. If you’re thin and always down on energy, you should raise the total number of calories that you eat. If you’re overweight, you should reduce your caloric intake and/or raise your activity level. An average of 2,100 kcal for women and 2,700 for men is a good base assumption – but everyone’s metabolism is slightly different. You may genuinely have a body/diet which leads to every ounce of energy being stripped from the food you take, or one which passes nearly everything through to the toilet.

For reference, 2,375 kcal is equivalent to a cheeseburger, a medium fries, a bowl of cereal, an orange, a salad, a cup of broccoli, two soft drinks, a slice of pumpkin pie, and a banana. As a rough estimate, it looks like if you assume 400 kcal for a main dish, 150 for a side, and 100 for a (non-water) beverage, you should be able to get by in daily life.

Name Estimate Real
Cheeseburger 400 600
Medium Fries 150 380
Bowl of Cereal 400 310
Orange 150 45
Salad 400 300
Broccoli 150 30
2x Soft Drinks 200 280
Slice of Pie 400 325
Banana 150 105
Total 2400 2375

Now, that’s more than I eat in a day and I’d definitely put on fat if I tried. I probably eat an average of 1200 kcal per day and still need to hit the gym regularly. Olympic athletes can eat up to 8,000 or 12,000 kcal per day (for some of the more energetic sports). Don’t expect your average, if you want to maintain a healthy weight, to be very close to the recommended average. Nor even that it will stay consistent from year-to-year. Our metabolisms change through our life, as do our activity levels. And don’t think that there’s something magical about your body that allows it to create fat no matter how little you eat. There may be some illness that causes people’s body to only produce fats instead of ATP out of food, but the lack of morbidly obese people in most of history and the planet is a fair indicator that if there is such an illness, it is a freak occurrence. But otherwise, basic physics tells us that it’s impossible to create fat unless you’ve ingested at least an equivalent amount of excess energy-producing material.

Essential nutrients are less flexible. I suspect that larger people would need to take more of certain nutrients (like vitamin K) to cover for the extra volume, though not all would have that sort of gain (since your skeleton and teeth stay the same size no matter how big you get it). But overall, the recommended daily intakes are probably a solid bet.

But so far as your body is concerned, at the end of the day, everything is just atoms and molecules. You could probably healthily live to a hundred eating lard and some wisely-chosen multivitamins. You could get your daily iron by biting off chunks of the Eiffel tower. Your body doesn’t really care how it was made or how tasty it was in your mouth, just whether the right components are there to be taken in and used.

So what is the best diet? Eat all the nutrients you need and adjust your caloric intake to adjust your weight. That’s really all it should come down to.

Hunger & Satisfaction

But the reality is that when people talk about diet, what they really mean is, “How can I lose weight while still feeling satisfied?” Granted, satisfaction has a few factors to it, the gratification of eating large, filling meals, the flavors and colors of the food before you, etc. Many people just wouldn’t be satisfied if they were asked to eat small, cold portions of clinically-prepared rations, regardless of whether it met their dietary needs or not. In some societies, like Japan, a small bowl of miso soup and a single small grilled fish counts as a perfectly full and complete meal. So terms like “large” and “inviting” are largely based on our expectations, but I can imagine that after decades of eating large plates, piled with foods draped in sauces, it’s hard to lower your sights.

But I think that the harder thing for most people to tackle is the prospect of hunger.

When we talk of instinct, really what we’re talking about is chemicals. Through evolutionary processes, what works (eating, mating, etc.) and what doesn’t (starvation, running off cliffs, etc.) have been determined for the species. And in general, your body produces chemicals when it senses that you’re doing things which are good for yourself and the species that we interpret as joy or satisfaction, and chemicals that we interpret as displeasure and stress when we’re doing things that are bad. This is nature’s stick and carrot to make us behave as it thinks we should.

Unfortunately, instinct is stupid. It can’t differentiate between success in ones life and injecting morphine into your blood stream – since the latter is just cutting out the middle man. But more saliently, it can’t differentiate between starving and shaving off the pounds, nor can it understand the difference between eating enough to live a healthy lifestyle and enough to sink a large boat.

In our bodies, hunger/satiation appears to be primarily modulated by Ghrelin (hunger), Leptin (general satisfaction), and Peptide YY (immediate satisfaction).

Information is scarce, but it looks like ghrelin is produced by the intestine when the abdomen’s own store of fat starts to get low. Seeing as food is necessary for life, and food becomes useful to us via the processing that happens in the intestine, it makes sense that hunger would be triggered when the intestine’s backup generator starts to run out of fuel. But consequently, the obese are rarely subjected to ghrelin (since they always have lots of extra fat) and their brains become more sensitive to it when it is released.

Leptin is produced by adipose tissue (i.e. fat-holding tissue). Leptin acts more like a gas meter, always visible to the brain. The more fat you have, the more leptin your body is producing at any given time (24-7). But unlike a gas meter, with a hard “Full” point at the top, our brain interprets more leptin as better. Raising it always feels better and you’ll always feel dissatisfied when it drops to a lower level. In the literature, this is referred to as “leptin resistance”.

Peptide YY is used as a signal for the body to start digesting food – and hence also used by the brain to detect that we have eaten and are satiated.

When one starts to lose weight, ghrelin production starts to occur more quickly and we respond to it worse if we’ve been overweight. And more importantly, we appear to stay sensitive to ghrelin even after we have lost weight. That is to say, if you used to be obese but are now a healthy weight, you’ll feel more hungry than people who were never overweight. While you’re in the process of losing weight, your leptin level reduces and you’ll feel generally dissatisfied with the world and stressed out. Fortunately, it looks like healthy living and exercise can reset your body’s leptin expectations to something lower. Peptide YY just reacts when food hits your colon so dieting shouldn’t affect much.

Overall, I’m not too concerned with leptin. I tend to think that people are more driven by immediate drives than long-term ones. Plus it looks like after the first few days of dieting (during which leptin levels drop significantly) leptin levels raise to normal levels and don’t affect you at a significant level. But the ability to modulate the other two would be a boon to the ease of dieting.

Ones expectation would be that we could do this by raising the fat-level of our abdomen quickly (so that ghrelin production is stopped) and to get food into our intestines quickly so that Peptide YY is released earlier.

In tests, it seems that ghrelin production can be diminished by eating carbohydrates. If we eat when ghrelin is produced – indicating that the intestines want to store fat – and eat something which can easily be converted into fat directly in the intestine, and the intestine will choose to store fat for itself before supplying the rest of the body. If that is indeed the case, then eating a small, high-carb snack when you feel hungry, might be a method to deal with this. The important factors to consider would be that this still counts towards your total daily caloric intake, and I must note that the total amount of fat stored in your abdomen is probably fairly small and I doubt that your body waits until your abdomen is on empty before signalling for more food. So the total amount that you need to eat to replenish your abdominal fat level is probably quite small.

For getting food through your gut quickly, fiber seems to be the go-to ingredient. But many high-carb items like potatoes and chips tend to be low on fiber and, in fact, travel through your intestines extra slow (reportedly). So rather than reaching for Fritos or Doritos when you’re feeling hungry and want a snack, the better options would probably be:

Legumes like peanuts and edamame
Natural grains like oats and whole wheat

The important thing for someone who has lost weight would probably be to remember that snacking is like taking medicine. There is a proper dosage and intake schedule. The goal isn’t to eat or enjoy a meal, it’s to pacify your body when it thinks you should be eating something, but when really you shouldn’t be. But also to realize if you have lost weight that this is something that you – due to raised ghrelin sensitivity – will have to do every day for the rest of your life. You need to make sure that you have the right type of snacks available, in the right quantities, and that you have incorporated them into your overall diet plan.


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