Eating for humans

I’m going to cover the topic of eating and dieting as best I can. This is a rant.

The most important thing to consider about dieting is that our bodies are a relic of our animal roots. The system by which we function was designed (evolved, how ever you want to look at it) back in a time when food was scarce and there wasn’t a lot of bartering. We’ve been farming for a few thousand years and we’ve had a commercial society — going to the store to buy what you want to eat that’s grown by someone else — for a few hundred years. The kind of change that would move us out of this space (once again, call it evolution or not, depending on what you believe) happens on the scale of tens- or hundreds-of-thousands of years. No one alive right now is going to be converted out of the cycle I describe.

At a very base level, you convert energy in food into energy used to run your metabolic systems. This is your heart and lungs, your muscles and also your brain. They all take energy to run. We measure energy in calories, which are actually kilocalories if you’re specific, and is a grossly simplified measure of energy as used by our bodies.

One calorie is the amount of heat (roughly, pure energy) necessary to raise one ounce of water by one degree Fahrenheit. It’s a great measure of a specific thing in the physical world. Because the numbers are large in the human-dietary scale, we use kilocalories, or thousands of calories. If it says on your chocolate bar that it’s 230 calories, the chocolate could be used to raise 10 gallons of water from room temperature of 72 F to 108 F, if you burnt it right under the water in a closed system.

Interestingly, that’s actually how a lot of the, “nutritional information,” on some foods has been calculated in the past. Set it on fire, see how much energy comes out, and that’s the caloric content.

Here’s the first big problem: I don’t know of anyone who has a blast furnace in their guts. Calories measure burn energy content, not the amount of energy that a human’s metabolic system gets from the food item. The human digestive system is much more complicated than that, and when it’s done processing what’s put in it, the result isn’t pure energy.

So at best calories are an approximation of how much energy is available in food. Just because 230 calories of pure energy are available in your chocolate bar, that doesn’t mean your body is getting that amount out of it.

The math is simple if you’re willing to abide by the approximation. There are 3,600 calories in a pound of fat. This is the kind of fat used in our bodies to store energy. Fat cells aren’t created or burned, they just gain and lose energy. (This is why liposuction works fairly well. It’s also a lot of the reason why people, “gain,” and, “lose,” the fat they carry in different places.) So a pound’s worth of fat cells can hold 3,600 calories.

Information on energy used in various activities is very readily available. Depending on your size and what activity you’re undertaking, you burn some number of tens to hundreds of calories per hour. Doing nothing — just letting your heart, lungs, brain, etc. go at it without using any of the muscles on the diagrams on the machines at the gym — is an activity. You can figure out your base metabolic rate (BMR) using various methods, some of which are simple approximations and others of which are somewhat ridiculously complicated. That’s basically the number of calories you burn in a day without doing anything else.

Calories in minus calories out divided by 3,600 is how many pounds of fat you gain in a day. Basically, if your BMR was 3,600 calories and you ate nothing and did nothing, you’d lose one pound a day. Unfortunately, the fact that a calorie is a bad measurement of metabolic energy use kinda torches that equation.

Part of the complexity rides in the fact that different foods contain different chemical structures to hold the energy. If you’re just burning it in a fire, that’s pretty irrelevant. But if you’re using it in a human metabolism, it’s probably more relevant than how many calories it contains. Depending on how your metabolism runs, for a variety of reasons, one calorie of burn energy in some food could end up delivering way less to your body. (Incidentally, it’s physically impossible for that calorie in the food to deliver more energy to your body, according to Newton’s Third Law.)

How your metabolism runs is a very delicate balance that has been the subject of many a fad diet. Some genetic things play a part, which is why most of us know that person who never seems to gain weight regardless of what or how much they eat. How much exercise you do makes a very large difference, hence our doctors’ constant insistence that we get a lot of it, regardless whether we’re dieting or not. Exercise doesn’t only burn calories; getting a lot of it also causes your BMR to change in a higher-numbered direction. Your level of hydration, stress or anxiety, mental activity, and other things like that change how your metabolism works also. But a key to this is also the content of the food.

The things we call, “carbohydrates,” are probably the simplest direct connection to energy content. Some carbohydrates are very close to 1-to-1 in terms of pure energy content versus how most bodies will process them. Fat is a very dense source of calories, which is slightly harder to digest but much more rewarding to the metabolism. Protein contains calories, somewhat tangentially, but they’re still there. Water — most of what most of your food is made of — contains none if it’s pure. Most other nutritional things, like vitamins and such, don’t contain enough to tip the scales in the quantity we eat them. We also stew over things like dietary fiber and amino acids, some of which are significant in this equation and some of which aren’t.

The formula of calories-in-minus-calories-out is good in some ways. A la Newton, it does establish a maximum criterion. If you ate 1,800 calories in a day, did nothing, and your BMR was 1,800 calories, you’d never gain any weight in fat because there simply wouldn’t be enough energy in the food you’re eating to deliver a net gain for your body to store. Also, it’s simple. Oversimplification sometimes gets us into trouble but a correct amount of simplification often gets us out of trouble as well. It’s also a functionally abstract formula: given the number of factors that go into the details and how nearly impossible it is to measure the in, the middle, or the out, the system is pretty much chaotic; a simplification is as good as any other way we have to figure it out quantitatively.

But that brings us to qualitative, which is really the more important part. It’s also where the animal brain comes in and also why it’s so difficult to diet. There’s a brain connected to this whole thing.

Those factors which affected your body’s ability to use food for energy also affect your brain’s desire for you to put food into your system. If you’re dehydrated, your brain is going to make you want to eat more because most of the food we eat contains mostly water, and it’s thinking it could work towards rehydration if it just had some more food to process. Long distance runners often have some problems keeping light because exercise makes your body want more nutritional content, which, if you’re not getting your dietary content perfect, means more food.

There’s an answer to each one of the problems. If you fast — essentially, if you don’t eat minuscule amounts constantly — your body will want to store extra energy to build up reserves for later, so don’t fast. If you have a disorder like diabetes, manage your intake carefully. (Diabetes is as much a disorder as aging — none of us are in perfect, “order,” or we’d never die. Life itself is a disorder.) Don’t think too much, maintain a stress-free life, eat a perfect diet (even though it’s impossible to know exactly what’s perfect for your body at any given moment), exercise several hours a day, hydrate perfectly, and you’ll always be in your top condition. There’s the answer. Good luck with that.

Enter the diet. Something is out of perfect alignment so we’re going to try to fix it. The real fix is complicated. I once knew a guy who was in great shape whose answer to staying trim all the time was to always go to bed hungry. The other side of the coin is the lemonade diet. Everyone has enough willpower to drink lemonade so what could possibly go wrong? Surely there’s some silver bullet, “trick,” that will make our bodies think they’re getting more than enough nutrition while eating just a little bit. Appetite is suppressed, weight is lost, the clouds part, beams of sunshine radiate, and angels sing.

Some diets do work for a while. Generally, the harder they are, the more they work. The quality, “hard,” is very subjective: Weight Watchers points are exciting to calculate for some and a total drag for others. Unfortunately, your body is much better at adapting than your brain is. Eventually, anything you do other than keeping a perfect balance will get adjusted out of perfection. The only thing that works consistently and permanently is hard work.

A great deal of the information we get is meant to mask the work. We’ve invented terms like, “trans fat,” and, “good fat.” All fats are good in the right amount and bad if overdone. We need fat to live because carbohydrates alone don’t have the energy density necessary to keep a human going at full steam. Eat too much of it — and fat is delicious because our brains are still trying to plan ahead for that time they’re sure is going to come when we don’t have enough energy stored to survive — and you gain weight. Our bodies are remarkably fantastic at managing our metabolism. Regardless of how many buzzwords or trends we hear and pay attention to, our bodies are never out to exact revenge or trick us. Every minute is a new minute to them and they’re going to try their best to handle right now and the future, even trying to do what they can to clean up past mistakes.

Just keeping a decent balance, even if a perfect one is out of reach, is hard work. It means not eating that thing you want to eat sometimes. It’s a lot like unconditional love of a child: doing something good now doesn’t mean you’re banking, “good points,” so you can do something bad later. The bad you do later is bad regardless how much good you did before.

Finally, on to how to eat like a human. Eat. Follow all the really good advice — not the advice that sounds easy or fun — from your doctor and your grandparents. Enjoy eating. Don’t do it as revenge. Listen to what your body tells you because it’s the closest thing to real information that you’re ever going to get. The fewer rules you have, things you don’t eat or refuse to eat, the better your health will be. Take the effort to make the difficult choice each and ever time it’s at all possible, including eating the right thing and getting the exercise. Don’t pay too close attention to little details because we’ve all been lied to so many times it’s impossible to count them. If something is all details — most fad diets are — it doesn’t deserve much attention. Always give yourself leeway to live life and never give let yourself go overboard on anything.

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