463 lines
22 KiB
Markdown
463 lines
22 KiB
Markdown
This blog post is part 2 of a series on nutrition and exercise. If you
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haven't seen it already, I recommend
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[reading part 1 now](/blog/2017/06/naive-overview-nutrition-exercise). This
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blog post will go into more details on nutrition.
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__For the completely impatient__, here are my recommendations on where you
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should get started, in a priority-sorted list (start with #1, and add
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more recommendations as you're ready):
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1. __Avoid eating processed foods.__ For example: sweet potato with
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butter? OK. Potato chips? Avoid.
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2. __Eat protein at each meal.__ Protein helps you feel full longer,
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helping avoid overeating.
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3. __Reduce your sugar intake.__ Sugar is addictive, has significantly
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negative health impacts, and encourages you to eat more than you
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should at each meal.
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4. __Pay attention to hunger cues.__ Stop eating before you feel
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"stuffed."
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Of course, I strongly recommend you read the rest of this blog post
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for more details.
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## Nutrients
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We need to get two different things from our food:
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* Essential nutrients
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* Energy
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Essential nutrients are things that our body requires to live, and
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cannot make itself. Energy is what powers us. Without either of these,
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we die. You've probably heard of calories before. A calorie is a unit
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of measurement for energy. Each person has different requirements for
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both essential nutrients and calories, which we'll get to shortly.
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The thing is that these two requirements overlap significantly. For
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example, Omega 3 fatty acids are an essential nutrient, but they also
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provide energy. Therefore, it's impossible to say something like "I'm
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going to get all of my energy from carbohydrates," since you'll be
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required to eat protein and fat as well.
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Alright, let's break down nutrients:
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* __Macronutrients__, aka __macros__, are either protein,
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carbohydrates (carbs), or fat. All three of these provide some level
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of energy (more on that later). As far as the essential aspects of
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these are concerned:
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* Protein is made up of _amino acids_. There are 21 different
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amino acids, of which 9 are _essential_. Amino acids are used
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by your body for building most of its structure (muscles,
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organs, bones).
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* There are two essential fatty acids: Omega 3 and
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Omega 6. You've probably heard a lot about Omega 3. That's
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because our modern diets (for reasons I won't get into) have a
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much higher level of Omega 6 relative to Omega 3, which is
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theorized to be a cause of many diseases via
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inflammation. That means you likely don't need to worry about
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getting enough Omega 6, but may want to supplement Omega 3
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(such as with fish oil pills).
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Other than that, you don't need to eat any fats. Your body can
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create its own fat (via *de novo lipogensis*) for fat storage.
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* There are no essential carbs. Fiber is a form of carbs that
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our bodies don't break down well, and help with
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digestion. Fiber also helps us feel full. But by saying it is
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non-essential, my point is: you can eat a diet without any
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carbs at all and survive. (Whether you should is a different
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issue.)
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* __Micronutrients__ are vitamins and minerals. There are many of
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these, and I'm not going to be getting into too many details here,
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because it's complicated, and I'm not all that familiar on the
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details. You can supplement these with multivitamins. But much
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better in my opinion is to eat real foods (as opposed to processed
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foods) that give you a good variety of micronutrients. A good
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general rule when choosing foods is: prefer foods which are dense in
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micronutrients, meaning lots of vitamins and minerals per calorie of
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food.
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__NOTE__ You also get calories from alcohol. I'm not going to discuss
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that here; alcohol is completely unnecessary in your diet, and has
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many negative impacts on health. I certainly enjoy a drink from time
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to time, but if you're drinking enough that the calorie impact of the
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alcohol is meaningful, you're sabotaging your health significantly.
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## Calories
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*Unimportant side note:* One calorie is the amount of energy needed to
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raise one gram of water one degree Celsius. When you read calories on
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food, it's actually talking about kilo-calories, or Calories (capital
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C), or food calories. The point is: there are a thousand "real"
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calories in a food calorie. I only mention this because it can be a
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point of confusion. We'll in general be talking about food calories,
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and just referring to them as calories.
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Each of the macronutrients provides a different amount of calories:
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* Fat: 9 calories/gram
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* Carbs: 4 calories/gram
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* Protein: 4 calories/gram
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But these numbers don't add up exactly as you'd expect. For example,
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protein is harder to convert into usable energy than the other two,
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and therefore it takes more energy to perform the breakdown. This is
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called the *thermic effect of food*, and means that you'll get less
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net energy from 9 grams of protein than from 4 grams of fat or 9 grams
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of carbs, even though in theory they should be the same.
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This brings us to our first important point: during digestion, each
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macronutrient follows a different metabolic pathway, and therefore can
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have different effects on the body. We'll cover the difference between
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carbs and fat in a later section. For now, I want to point out that
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protein is a suboptimal energy source. This greatly affects how we
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want to consider protein as part of our diet (also in an upcoming
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section).
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## Total Daily Energy Expenditure
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Your body needs energy to operate. The total energy it needs on a
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daily basis is the TDEE, or Total Daily Energy Expenditure. If you eat
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more energy than this number, the excess will be stored as fat. If you
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eat less, the difference will be taken from fat. This is known as
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calories-in/calories-out.
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You'll see lots of debates online about this point. Here's my personal
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take: it's a truism, but misses a lot of the point. Yes, if you eat a
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lot more food, you'll put on weight. But the situation is quite a bit
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more complicated than this. The amount and type of food you eat
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affects hormone levels that influence your energy expenditure and
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hunger levels. And while my simplified model talks about adding and
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losing fat, we have other body mass (glycogen and muscle) which will
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be affected as well.
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What's my point in all of this? Yes, you should be aware of your
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TDEE. Let it be a general guide (in addition to hunger signals) to how
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much you should eat. But realize it's an estimate, and that trying to
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change it (such as by eating only 500 calories a day) will not
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immediately result in losing the amount of fat you expect. Your body
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may slow down its metabolism to compensate, you may cheat more often,
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etc.
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You can find lots of TDEE calculators online,
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[here's one I find with a quick search](https://tdeecalculator.net/). Also,
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one pound of body fat contains 3500 calories (7700 per kilogram), so
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in theory, you'd need to eat at a calorie deficit of 500 calories per
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day for a week to lose one pound of fat.
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## Protein Requirements
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Since, as we said above, protein isn't a great source for energy, we
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primarily want to include protein in our diet for its non-energy
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aspects. This involves the "essential" bit about providing amino
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acids. However, there's another big benefit that comes from eating
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protein: you tend to stay full longer when you eat protein. One
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recommendation that I like to follow is to include a protein source in
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every meal.
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So then the question is: how much protein do you need? You'll see lots
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of values thrown around for this. For example, 1 gram of protein per
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pound of bodyweight. That means, if you weigh 170 pounds (77kg for
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those of us outside the US), you'd target 170 grams of protein per
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day. But numbers really vary all over the place. Some standards place
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this as a certain number of grams per pound of *lean* body weight
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(meaning, ignoring your body fat). How much you need also varies with
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what kind of activity you're doing: if you're trying to build muscle,
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you'll usually want to eat more protein.
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I'd recommend doing some research yourself on how much protein you
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need to get per day, I'm going to avoid making a recommendation. I
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will, instead, try to debunk some myths:
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* If you eat only 100% protein all day, you're not going to grow super
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muscles. Eventually,
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[you'll die](https://en.wikipedia.org/wiki/Protein_poisoning) from
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something known as rabbit starvation.
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* That said, eating a high-protein diet, above the Recommended Daily
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Allowance, isn't going to send you into renal (kidney)
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failure. Unless you have some preexisting condition, you'll be able
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to handle a fairly high protein level without issue.
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One of the biggest downsides with protein is that it tends to be
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relatively expensive (compare the cost of a steak vs a loaf of
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bread). Also, different protein sources have different absorption
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rates in the body. Finally, referring back to the essential amino
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acids, not all protein sources are _complete_, especially not vegan
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ones. (Complete here means it contains all 9 essential amino acids.)
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If you're eating animal products, you're probably fine. With vegan
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products, do a little more research on what you're eating (hemp seed
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and quinoa are both complete proteins).
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__Summary__ Get enough protein, and eat it at each meal to help you
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stay full longer.
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## Carbs vs fat
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Alright, once you're done putting protein into your diet, you'll be
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filling up the rest of your calories from carbs and fat. This is
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probably one of the biggest areas where that issue of complication I
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mentioned comes into play. If you want my simple recommendation: start
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off by getting adequate protein and avoiding processed foods. In my
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opinion, you'll be getting 80% of the way to a great diet with just
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those steps.
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OK, you want to get into the details of carbs vs fat? I would say
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that, first and foremost, a lot of the most sensational claims out
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there are simply not true. Fat doesn't clog your arteries. Carbs don't
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magically make you fat. Things are far more nuanced. I'm going to give
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a list of benefits for each of these macronutrients.
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__Benefits of carbs__
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* Since they are less calorically dense than fat, you can eat more of
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them and get the same amount of calories
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* Carbs are part of what people often consider healthy foods, like
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fruits, vegetables, legumes, and grains. (I encourage you to
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especially research whether fruits and grains should be considered
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healthy in general. I'd recommend moderating fruit intake due to
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high sugar, and especially fructose, levels.)
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* Carbs tend to be the cheapest macronutrient available
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* Many high carb foods are also high fiber foods, which is good for
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digestion and satiety
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* Carbs are broken down into glucose in the body, and stored in the
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body as glycogen, which is a faster burning energy source than
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fat. This makes carbs good for explosive activity (like weight
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lifting or sprinting).
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* Unlike fats, carbs cannot be stored directly in the body as
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fat. They need to first be converted to fat via a process called *de
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novo lipogensis*, which loses some energy in the process. In other
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words, 500 calories of excess carbs will result in less body fat vs
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500 calories of excess fat.
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* That said, if you eat both fat and carbs in your diet, your body
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will prefer to burn the carbs and store the fat, so given a fair
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mix of both macronutrients, this won't matter too much.
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__Benefits of fats__
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* Fat tends to leave you feeling fuller longer, since digestion of fat
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is slower. This is very likely the primary mechanism by which
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low-carb diets help you lose weight.
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* If you almost completely eliminate carbs, your body will enter a
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state called ketosis, where your liver generates *ketone bodies* for
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your brain and other organs to run off of. This can have great fat
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burning results, and can be used for treating some neurological
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conditions (like epilepsy).
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* Eating insufficient fat can lead to hormonal imbalances, and the
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so-called "starvation mode." Having a high-fat low-carb diet can
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allow you to eat less total calories without having your apetite
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ramped up or your metabolism turned down.
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* If you eat primarily fat, your body gets better at turning fat into
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usable energy. This doesn't just apply to dietary fat, but to your
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body fat too. This is sometimes referred to as being a "fat burner."
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* Glycogen (stored carbs) is very limited in capacity in the body. By
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contrast, even extremely lean people have many tens of thousands of
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calories available in fat. If your body is good at burning fat, it
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can be a big advantage for endurance activities like marathon
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running or cycling.
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* Fats taste good. Carbs can taste good too, but that usually depends
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on the presence of sugar. Most people agree today that sugar is a
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pretty dangerous substance for the body and should be avoided.
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There are clearly arguments in favor of both macronutrients. I'd argue
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that it has been the obvious case throughout human history that we
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have eaten diets high in carbs, high in fats, and high in both, and we
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can survive well on any of them. I've personally used all kinds of
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diets with good results.
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There is one thing I've seen claimed that I think has a lot of logic
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to it. Some of the most successful diets today seem to be based around
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banning either carbs or fat. Perhaps the reason they work is that the
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biggest reward foods—ice cream, potato chips, chocolate,
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etc—are high in both carbs and fat. By allowing yourself large
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quantities of food, but naturally avoiding these highly tempting and
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easy-to-binge reward foods, it becomes much easier to adhere to a
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diet.
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__My recommendation__ Unless you have some ethical or religious reason
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guiding your eating, try out whatever popular diet plan appeals to
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you. Give it a few weeks at least, ideally a few months, and see how
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you respond. If you find that you're constantly fighting cravings even
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after trying the diet for a few weeks, consider trying something
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else. And if you are not losing body fat, either the diet's a bad one
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(don't fall for the ice cream diet!) or you're not following it well.
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## Glycogen and water weight
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I mentioned above that carbs get stored as glycogen. When your body
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stores glycogen, it stores some water to go along with it. This is one
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of the reasons why low carb diets have such amazing short term
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results: when you first become fat adapted, you burn up your glycogen
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stores quickly, and flush out that extra water (in your urine) at the
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same time. You can lose a few pounds/kilos in a few short days.
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Don't fall into this all-too-common trap:
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> Wow, I lost 3 pounds in my first week alone! This is great! If I
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> just continue like this for the next 2 months, I'll lose 25 pounds
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> in no time!
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Then, when you of course can't continue peeing out 2.5 pounds of water
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per week and you eventually hit a weight loss plateu, you decide your
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diet isn't working and give up. In other words:
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__Be wary of the scale, it will lie to you!__
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## Intermittent fasting
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Something popping up much more recently is intermittent fasting, where
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you spend a certain number of hours per day not eating. Perhaps the
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most common is the 16-8 fast: you fast 16 hours and only eat
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for 8. That might sound rough, but when you realize that sleep is part
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of this, and the schedule is "fit all of your eating into 11am-7pm or
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similar", it's not too bad.
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There are some theoretical health benefits of fasting on its own. Our
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bodies can swing between catabolic (breaking down) and anabolic
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(building up) phases, and there are advantages to both. If we're
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constantly stuffing our faces, our body never has to enter catabolism,
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which can be detrimental.
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But intermittent fasting has a much simpler motivator: it makes it
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easier to eat within your TDEE if you don't spend all day eating. And
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during the part of the day you're not eating, it's much easier to
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control yourself. At least for me, a simple binary on/off switch for
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"am I allowed to eat" is easy.
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Do you have to do this? Absolutely not. But if you're feeling like
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trying something, go for it. If nothing else, convincing yourself that
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you're strong enough to go regularly without eating is a good
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psychological barrier to overcome.
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## Different types of fat
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Saturated. Unsaturated. Monounsaturated. Polyunsaturated. Omegas. Trans.
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What's up with all of this? Well, it's just chemistry. Fats are chains
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of carbons. Each carbon can form four bonds, and hydrogen can form one
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bond. So in theory, each carbon can bond to the carbon to its left,
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the carbon to its right, and two hydrogens. If that happens, you have
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a saturated fat. This is saturated because each carbon is fully
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saturated by two hydrogens.
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However, sometimes we'll be missing hydrogens. Instead of binding to
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two hydrogens, two carbons can form a double bond. Each of those
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carbons will bond with one hydrogen and one other neighboring
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carbon. When such a double bond forms, we have an unsaturated
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fat. Because double bonds are more flexible, unsaturated fats melt
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(turn liquid) at lower temperatures. That's why saturated fats (like
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butter) tend to be solid at room temperature, but unsaturated fats
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(like olive oil) are liquid.
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If a fat has just one double bond in it, it's monounsaturated. If it
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has more than one, it's polyunsaturated. Two of these polyunsaturated
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fats are special: omega 3 and omega 6 are differentiated by the
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distance between the tail of the carbon chain and the first double
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bond.
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Trans fats are unsaturated fats which have been chemically altered to
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make them solid at higher temperatures. This is done by hydrogenating
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them. Because trans fats occur very rarely naturally, it seems that
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our bodies are not particularly good at digesting them, with the
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result being that they're bad for our health. Basically: avoid trans
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fats.
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As mentioned above, both omega 3 and omega 6 are essential fatty
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acids. We get plenty of omega 6, so you should try to get more omega
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3.
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Beyond that, what kind of fats should you go for? That's a topic of
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much debate. Up until recently, the answer would be to prefer
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polyunsaturated vegetable oils. However, newer evidence points to
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saturated fat not being the villain it was thought to be, and
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vegetable oil in fact being dangerous. Monounsaturated
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fats—especially olive oil—seem to be pretty well accepted
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as being good for us.
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Personally, I avoid vegetable oils and don't avoid saturated fats. But
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you'll get lots of conflicting advice on this area. I recommend
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reading up.
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## Different types of carbs
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Simple. Complex. Sugar. Glucose. Fructose. Lactose. Starch. What
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exactly are carbs? Time for some more chemistry!
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*Saccharide* is another term of carbohydrates. The *monosaccharides*
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and *disaccharides* make up what we call the sugars. The most common
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monosaccharides are:
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* Glucose
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* Fructose
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* Galactose
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Disaccharides are pairs of monosaccharides, such as:
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* Sucrose (table sugar) = glucose + fructose
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* Lactose (milk sugar) = galactose + fructose
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* Maltose = glucose + glucose
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Longer chains of saccharides form *polysaccharides*, such as starch (as
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you'd find in potatos or rice) and cellulose. Cellulose gives plants
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their structure and is indigestible (for the most part) to humans;
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you've already seen it referred to here as dietary fiber. However,
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some gut bacteria can digest fiber and generate molecules we _can_
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digest.
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When digesting, our body will break down carbohydrates into
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monosaccharides so they can be absorbed in the large
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intenstine. Because this breakdown takes time, the more *complex* the
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carbohydrate (meaning the more saccharides are bound together), the
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slower the digestion. This will leave you feeling full longer and
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avoid a blood sugar spike.
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When your blood sugar spikes, your body releases insulin to remove the
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toxic levels of sugar from the blood and store it as glycogen and
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fat. One working theory is that, when you eat a diet filled with
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simple sugars, you bounce between sugar highs and sugar crashes, the
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latter leaving you hungry and irritable, and reaching for that next
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sugary snack. All this is to say: avoid simple sugars!
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One method for measuring how quickly carbs are absorbed is the
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_glycemic index_ (GI), where a higher value means the food is more
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quickly absorbed. By this standard, you should probably stick to low
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GI foods, unless you have a specific reason to do otherwise (such as
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some kind of athletic competition or muscle recovery... but that's
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complicated and you should do research on it before trying it out).
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Of the three monosaccharides, glucose is the one that our body cells
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can use directly. Fructose and galactose must be processed first by
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the liver. There are some claims that having a high-fructose diet can
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put undue strain on the liver, giving one reason why High Fructose
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Corn Syrup has such a bad rap. This is also a reason why binge-eating
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fruit—which is high in fructose—may not be a great idea.
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## Salt
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I'm only putting in this section because people will ask. The story
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with salt is, in my opinion, completely unclear. There are many
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contradictory studies. If you have hypertension, general consensus is
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to reduce salt. Beyond that, conventional wisdom says reducing salt is
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a good thing, but many newer studies show that it has no benefit. And
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also, if you're going for a ketogenic diet, make sure to get plenty of
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electrolytes, including salt, potassium, and magnesium.
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## Summary of Nutrition
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Whew, that's a lot of information! Let me try to simplify all of that
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down into some practical advice.
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* Avoid processed foods. They're made up of the worst combination of
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foods that basically everyone agrees will kill you: processed oils,
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simple sugars and starches, chemicals, and excess salt. Honestly,
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just following this one piece of advice is in my opinion the best
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thing you can do for your health.
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* Eat plenty of protein, and try to get it with each meal.
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* Don't eat too many calories in the course of a day.
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* Balance your carbs and fats based on your calorie needs. Try out
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variations of that balance and see what works for you.
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* Get sufficient omega 3s.
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* If necessary, supplement vitamins and minerals.
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I'll tie up this series in my next post, which will go into details on
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exercise.
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