A Very Naive Overview of Nutrition (Part 2)

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This blog post is part 2 of a series on nutrition and exercise. If you haven't seen it already, I recommend reading part 1 now. This blog post will go into more details on nutrition.

For the completely impatient, here are my recommendations on where you should get started, in a priority-sorted list (start with #1, and add more recommendations as you're ready):

Avoid eating processed foods. For example: sweet potato with butter? OK. Potato chips? Avoid.
Eat protein at each meal. Protein helps you feel full longer, helping avoid overeating.
Reduce your sugar intake. Sugar is addictive, has significantly negative health impacts, and encourages you to eat more than you should at each meal.
Pay attention to hunger cues. Stop eating before you feel "stuffed."

Of course, I strongly recommend you read the rest of this blog post for more details.

Nutrients

We need to get two different things from our food:

Essential nutrients
Energy

Essential nutrients are things that our body requires to live, and cannot make itself. Energy is what powers us. Without either of these, we die. You've probably heard of calories before. A calorie is a unit of measurement for energy. Each person has different requirements for both essential nutrients and calories, which we'll get to shortly.

The thing is that these two requirements overlap significantly. For example, Omega 3 fatty acids are an essential nutrient, but they also provide energy. Therefore, it's impossible to say something like "I'm going to get all of my energy from carbohydrates," since you'll be required to eat protein and fat as well.

Alright, let's break down nutrients:

Macronutrients, aka macros, are either protein, carbohydrates (carbs), or fat. All three of these provide some level of energy (more on that later). As far as the essential aspects of these are concerned:
- Protein is made up of amino acids. There are 21 different amino acids, of which 9 are essential. Amino acids are used by your body for building most of its structure (muscles, organs, bones).
- There are two essential fatty acids: Omega 3 and Omega 6. You've probably heard a lot about Omega 3. That's because our modern diets (for reasons I won't get into) have a much higher level of Omega 6 relative to Omega 3, which is theorized to be a cause of many diseases via inflammation. That means you likely don't need to worry about getting enough Omega 6, but may want to supplement Omega 3 (such as with fish oil pills).
  
  Other than that, you don't need to eat any fats. Your body can create its own fat (via de novo lipogensis) for fat storage.
- There are no essential carbs. Fiber is a form of carbs that our bodies don't break down well, and help with digestion. Fiber also helps us feel full. But by saying it is non-essential, my point is: you can eat a diet without any carbs at all and survive. (Whether you should is a different issue.)
Micronutrients are vitamins and minerals. There are many of these, and I'm not going to be getting into too many details here, because it's complicated, and I'm not all that familiar on the details. You can supplement these with multivitamins. But much better in my opinion is to eat real foods (as opposed to processed foods) that give you a good variety of micronutrients. A good general rule when choosing foods is: prefer foods which are dense in micronutrients, meaning lots of vitamins and minerals per calorie of food.

NOTE You also get calories from alcohol. I'm not going to discuss that here; alcohol is completely unnecessary in your diet, and has many negative impacts on health. I certainly enjoy a drink from time to time, but if you're drinking enough that the calorie impact of the alcohol is meaningful, you're sabotaging your health significantly.

Calories

Unimportant side note: One calorie is the amount of energy needed to raise one gram of water one degree Celsius. When you read calories on food, it's actually talking about kilo-calories, or Calories (capital C), or food calories. The point is: there are a thousand "real" calories in a food calorie. I only mention this because it can be a point of confusion. We'll in general be talking about food calories, and just referring to them as calories.

Each of the macronutrients provides a different amount of calories:

Fat: 9 calories/gram
Carbs: 4 calories/gram
Protein: 4 calories/gram

But these numbers don't add up exactly as you'd expect. For example, protein is harder to convert into usable energy than the other two, and therefore it takes more energy to perform the breakdown. This is called the thermic effect of food, and means that you'll get less net energy from 9 grams of protein than from 4 grams of fat or 9 grams of carbs, even though in theory they should be the same.

This brings us to our first important point: during digestion, each macronutrient follows a different metabolic pathway, and therefore can have different effects on the body. We'll cover the difference between carbs and fat in a later section. For now, I want to point out that protein is a suboptimal energy source. This greatly affects how we want to consider protein as part of our diet (also in an upcoming section).

Total Daily Energy Expenditure

Your body needs energy to operate. The total energy it needs on a daily basis is the TDEE, or Total Daily Energy Expenditure. If you eat more energy than this number, the excess will be stored as fat. If you eat less, the difference will be taken from fat. This is known as calories-in/calories-out.

You'll see lots of debates online about this point. Here's my personal take: it's a truism, but misses a lot of the point. Yes, if you eat a lot more food, you'll put on weight. But the situation is quite a bit more complicated than this. The amount and type of food you eat affects hormone levels that influence your energy expenditure and hunger levels. And while my simplified model talks about adding and losing fat, we have other body mass (glycogen and muscle) which will be affected as well.

What's my point in all of this? Yes, you should be aware of your TDEE. Let it be a general guide (in addition to hunger signals) to how much you should eat. But realize it's an estimate, and that trying to change it (such as by eating only 500 calories a day) will not immediately result in losing the amount of fat you expect. Your body may slow down its metabolism to compensate, you may cheat more often, etc.

You can find lots of TDEE calculators online, here's one I find with a quick search. Also, one pound of body fat contains 3500 calories (7700 per kilogram), so in theory, you'd need to eat at a calorie deficit of 500 calories per day for a week to lose one pound of fat.

Protein Requirements

Since, as we said above, protein isn't a great source for energy, we primarily want to include protein in our diet for its non-energy aspects. This involves the "essential" bit about providing amino acids. However, there's another big benefit that comes from eating protein: you tend to stay full longer when you eat protein. One recommendation that I like to follow is to include a protein source in every meal.

So then the question is: how much protein do you need? You'll see lots of values thrown around for this. For example, 1 gram of protein per pound of bodyweight. That means, if you weigh 170 pounds (77kg for those of us outside the US), you'd target 170 grams of protein per day. But numbers really vary all over the place. Some standards place this as a certain number of grams per pound of lean body weight (meaning, ignoring your body fat). How much you need also varies with what kind of activity you're doing: if you're trying to build muscle, you'll usually want to eat more protein.

I'd recommend doing some research yourself on how much protein you need to get per day, I'm going to avoid making a recommendation. I will, instead, try to debunk some myths:

If you eat only 100% protein all day, you're not going to grow super muscles. Eventually, you'll die from something known as rabbit starvation.
That said, eating a high-protein diet, above the Recommended Daily Allowance, isn't going to send you into renal (kidney) failure. Unless you have some preexisting condition, you'll be able to handle a fairly high protein level without issue.

One of the biggest downsides with protein is that it tends to be relatively expensive (compare the cost of a steak vs a loaf of bread). Also, different protein sources have different absorption rates in the body. Finally, referring back to the essential amino acids, not all protein sources are complete, especially not vegan ones. (Complete here means it contains all 9 essential amino acids.) If you're eating animal products, you're probably fine. With vegan products, do a little more research on what you're eating (hemp seed and quinoa are both complete proteins).

Summary Get enough protein, and eat it at each meal to help you stay full longer.

Carbs vs fat

Alright, once you're done putting protein into your diet, you'll be filling up the rest of your calories from carbs and fat. This is probably one of the biggest areas where that issue of complication I mentioned comes into play. If you want my simple recommendation: start off by getting adequate protein and avoiding processed foods. In my opinion, you'll be getting 80% of the way to a great diet with just those steps.

OK, you want to get into the details of carbs vs fat? I would say that, first and foremost, a lot of the most sensational claims out there are simply not true. Fat doesn't clog your arteries. Carbs don't magically make you fat. Things are far more nuanced. I'm going to give a list of benefits for each of these macronutrients.

Benefits of carbs

Since they are less calorically dense than fat, you can eat more of them and get the same amount of calories
Carbs are part of what people often consider healthy foods, like fruits, vegetables, legumes, and grains. (I encourage you to especially research whether fruits and grains should be considered healthy in general. I'd recommend moderating fruit intake due to high sugar, and especially fructose, levels.)
Carbs tend to be the cheapest macronutrient available
Many high carb foods are also high fiber foods, which is good for digestion and satiety
Carbs are broken down into glucose in the body, and stored in the body as glycogen, which is a faster burning energy source than fat. This makes carbs good for explosive activity (like weight lifting or sprinting).
Unlike fats, carbs cannot be stored directly in the body as fat. They need to first be converted to fat via a process called de novo lipogensis, which loses some energy in the process. In other words, 500 calories of excess carbs will result in less body fat vs 500 calories of excess fat.
- That said, if you eat both fat and carbs in your diet, your body will prefer to burn the carbs and store the fat, so given a fair mix of both macronutrients, this won't matter too much.

Benefits of fats

Fat tends to leave you feeling fuller longer, since digestion of fat is slower. This is very likely the primary mechanism by which low-carb diets help you lose weight.
If you almost completely eliminate carbs, your body will enter a state called ketosis, where your liver generates ketone bodies for your brain and other organs to run off of. This can have great fat burning results, and can be used for treating some neurological conditions (like epilepsy).
Eating insufficient fat can lead to hormonal imbalances, and the so-called "starvation mode." Having a high-fat low-carb diet can allow you to eat less total calories without having your apetite ramped up or your metabolism turned down.
If you eat primarily fat, your body gets better at turning fat into usable energy. This doesn't just apply to dietary fat, but to your body fat too. This is sometimes referred to as being a "fat burner."
Glycogen (stored carbs) is very limited in capacity in the body. By contrast, even extremely lean people have many tens of thousands of calories available in fat. If your body is good at burning fat, it can be a big advantage for endurance activities like marathon running or cycling.
Fats taste good. Carbs can taste good too, but that usually depends on the presence of sugar. Most people agree today that sugar is a pretty dangerous substance for the body and should be avoided.

There are clearly arguments in favor of both macronutrients. I'd argue that it has been the obvious case throughout human history that we have eaten diets high in carbs, high in fats, and high in both, and we can survive well on any of them. I've personally used all kinds of diets with good results.

There is one thing I've seen claimed that I think has a lot of logic to it. Some of the most successful diets today seem to be based around banning either carbs or fat. Perhaps the reason they work is that the biggest reward foods—ice cream, potato chips, chocolate, etc—are high in both carbs and fat. By allowing yourself large quantities of food, but naturally avoiding these highly tempting and easy-to-binge reward foods, it becomes much easier to adhere to a diet.

My recommendation Unless you have some ethical or religious reason guiding your eating, try out whatever popular diet plan appeals to you. Give it a few weeks at least, ideally a few months, and see how you respond. If you find that you're constantly fighting cravings even after trying the diet for a few weeks, consider trying something else. And if you are not losing body fat, either the diet's a bad one (don't fall for the ice cream diet!) or you're not following it well.

Glycogen and water weight

I mentioned above that carbs get stored as glycogen. When your body stores glycogen, it stores some water to go along with it. This is one of the reasons why low carb diets have such amazing short term results: when you first become fat adapted, you burn up your glycogen stores quickly, and flush out that extra water (in your urine) at the same time. You can lose a few pounds/kilos in a few short days.

Don't fall into this all-too-common trap:

Wow, I lost 3 pounds in my first week alone! This is great! If I just continue like this for the next 2 months, I'll lose 25 pounds in no time!

Then, when you of course can't continue peeing out 2.5 pounds of water per week and you eventually hit a weight loss plateu, you decide your diet isn't working and give up. In other words:

Be wary of the scale, it will lie to you!

Intermittent fasting

Something popping up much more recently is intermittent fasting, where you spend a certain number of hours per day not eating. Perhaps the most common is the 16-8 fast: you fast 16 hours and only eat for 8. That might sound rough, but when you realize that sleep is part of this, and the schedule is "fit all of your eating into 11am-7pm or similar", it's not too bad.

There are some theoretical health benefits of fasting on its own. Our bodies can swing between catabolic (breaking down) and anabolic (building up) phases, and there are advantages to both. If we're constantly stuffing our faces, our body never has to enter catabolism, which can be detrimental.

But intermittent fasting has a much simpler motivator: it makes it easier to eat within your TDEE if you don't spend all day eating. And during the part of the day you're not eating, it's much easier to control yourself. At least for me, a simple binary on/off switch for "am I allowed to eat" is easy.

Do you have to do this? Absolutely not. But if you're feeling like trying something, go for it. If nothing else, convincing yourself that you're strong enough to go regularly without eating is a good psychological barrier to overcome.

Different types of fat

Saturated. Unsaturated. Monounsaturated. Polyunsaturated. Omegas. Trans. What's up with all of this? Well, it's just chemistry. Fats are chains of carbons. Each carbon can form four bonds, and hydrogen can form one bond. So in theory, each carbon can bond to the carbon to its left, the carbon to its right, and two hydrogens. If that happens, you have a saturated fat. This is saturated because each carbon is fully saturated by two hydrogens.

However, sometimes we'll be missing hydrogens. Instead of binding to two hydrogens, two carbons can form a double bond. Each of those carbons will bond with one hydrogen and one other neighboring carbon. When such a double bond forms, we have an unsaturated fat. Because double bonds are more flexible, unsaturated fats melt (turn liquid) at lower temperatures. That's why saturated fats (like butter) tend to be solid at room temperature, but unsaturated fats (like olive oil) are liquid.

If a fat has just one double bond in it, it's monounsaturated. If it has more than one, it's polyunsaturated. Two of these polyunsaturated fats are special: omega 3 and omega 6 are differentiated by the distance between the tail of the carbon chain and the first double bond.

Trans fats are unsaturated fats which have been chemically altered to make them solid at higher temperatures. This is done by hydrogenating them. Because trans fats occur very rarely naturally, it seems that our bodies are not particularly good at digesting them, with the result being that they're bad for our health. Basically: avoid trans fats.

As mentioned above, both omega 3 and omega 6 are essential fatty acids. We get plenty of omega 6, so you should try to get more omega

Beyond that, what kind of fats should you go for? That's a topic of much debate. Up until recently, the answer would be to prefer polyunsaturated vegetable oils. However, newer evidence points to saturated fat not being the villain it was thought to be, and vegetable oil in fact being dangerous. Monounsaturated fats—especially olive oil—seem to be pretty well accepted as being good for us.

Personally, I avoid vegetable oils and don't avoid saturated fats. But you'll get lots of conflicting advice on this area. I recommend reading up.

Different types of carbs

Simple. Complex. Sugar. Glucose. Fructose. Lactose. Starch. What exactly are carbs? Time for some more chemistry!

Saccharide is another term of carbohydrates. The monosaccharides and disaccharides make up what we call the sugars. The most common monosaccharides are:

Glucose
Fructose
Galactose

Disaccharides are pairs of monosaccharides, such as:

Sucrose (table sugar) = glucose + fructose
Lactose (milk sugar) = galactose + fructose
Maltose = glucose + glucose

Longer chains of saccharides form polysaccharides, such as starch (as you'd find in potatos or rice) and cellulose. Cellulose gives plants their structure and is indigestible (for the most part) to humans; you've already seen it referred to here as dietary fiber. However, some gut bacteria can digest fiber and generate molecules we can digest.

When digesting, our body will break down carbohydrates into monosaccharides so they can be absorbed in the large intenstine. Because this breakdown takes time, the more complex the carbohydrate (meaning the more saccharides are bound together), the slower the digestion. This will leave you feeling full longer and avoid a blood sugar spike.

When your blood sugar spikes, your body releases insulin to remove the toxic levels of sugar from the blood and store it as glycogen and fat. One working theory is that, when you eat a diet filled with simple sugars, you bounce between sugar highs and sugar crashes, the latter leaving you hungry and irritable, and reaching for that next sugary snack. All this is to say: avoid simple sugars!

One method for measuring how quickly carbs are absorbed is the glycemic index (GI), where a higher value means the food is more quickly absorbed. By this standard, you should probably stick to low GI foods, unless you have a specific reason to do otherwise (such as some kind of athletic competition or muscle recovery... but that's complicated and you should do research on it before trying it out).

Of the three monosaccharides, glucose is the one that our body cells can use directly. Fructose and galactose must be processed first by the liver. There are some claims that having a high-fructose diet can put undue strain on the liver, giving one reason why High Fructose Corn Syrup has such a bad rap. This is also a reason why binge-eating fruit—which is high in fructose—may not be a great idea.

Salt

I'm only putting in this section because people will ask. The story with salt is, in my opinion, completely unclear. There are many contradictory studies. If you have hypertension, general consensus is to reduce salt. Beyond that, conventional wisdom says reducing salt is a good thing, but many newer studies show that it has no benefit. And also, if you're going for a ketogenic diet, make sure to get plenty of electrolytes, including salt, potassium, and magnesium.

Summary of Nutrition

Whew, that's a lot of information! Let me try to simplify all of that down into some practical advice.

Avoid processed foods. They're made up of the worst combination of foods that basically everyone agrees will kill you: processed oils, simple sugars and starches, chemicals, and excess salt. Honestly, just following this one piece of advice is in my opinion the best thing you can do for your health.
Eat plenty of protein, and try to get it with each meal.
Don't eat too many calories in the course of a day.
Balance your carbs and fats based on your calorie needs. Try out variations of that balance and see what works for you.
Get sufficient omega 3s.
If necessary, supplement vitamins and minerals.

I'll tie up this series in my next post, which will go into details on exercise.