Carbohydrate Low-down: how many carbohydrates should you eat?

Time to tackle another head of what I consider the 3-headed beast of nutrition: carbohydrates. Especially in the field of dietetics and nutrition, there is a a pseudo-war about whether clients should restrict carbohydrates to see health benefits. And I swear, after this post, I will not be posting monster 3,000 + word posts again.

Every other month, there is a study that either touts or refutes the benefits of either carbohydrate restriction or carbohydrate liberation. Who’s wrong, who’s right?

First, I want to tell you what the other two heads are:

1) Saturated fat and cholesterol
2) Salt

And today, we are going to talk about carbohydrates.

What are carbohydrates (carbs)?

Carbohydrates are energy nutrients, just like protein and fat. They provide the body with substrates to keep it functioning optimally. We are not going to talk about biochemistry here, such as which processes that involved in carbohydrate metabolism, where carbohydrates get absorbed, and the finer details of what happens to carbohydrates after they do get absorbed.

Carbohydrates are made up of three elements: carbon, hydrogen, and oxygen. Through a complex metabolic process, carbohydrate sources like bread, potatoes, and fruit are eaten and subsequently broken down into three simple sugar molecules: fructose, glucose, and galactose. They are the preferred energy source for red blood, brain, and muscle cells, especially during periods of high-intense activities. Carbs are stored in two primary tissues of the body: liver and muscle. The storage capacity of carbs in the liver is ~100g in average humans and 300-500 in muscle, for an average of 400-600g of storage capacity in an average person at any time (Acheson; Jensen).


Mmmm, carbs (source)

Carbohydrates in and of themselves are not evil–far from it. Carbohydrates stimulate the release of insulin, which is an anabolic–building–hormone. Don’t know what insulin is because you’ve been living under a rock? It’s a hormone that acts on your body cells, opening them up like a key and lock, in order to remove sugar from the blood caused by eating carbohydrates. Insulin is a requirement if you want to build muscle. Insulin is also anti-inflammatory, meaning that some carbohydrates are actually required for proper immune function (Hyun).

Whether or not carbohydrates are necessary is something that experts like to debate about. This is where things can get a bit tricky. Notice how I said “preferred”. Some experts like to take it further and suggest that carbohydrates are either not necessary for survival or that you should eat a high-carbohydrate diet.

What is ‘low’?


And it ain’t twerkin’ (source)

Let me just say this: twerking is a menace to our society.

When you look at the research, it’s clear that ‘low-carbohydrate’ does not have a uniform definition. For example, studies done by Volek et al use low-carbohydrate plans that consist of less than 20g of carbohydrates per day. These are also called ‘ketogenic’ diets. Other researchers consider 40% of daily carbohydrate intake low, or 60g or less per day, or 130g or less per day (this 130g figure comes from the idea that the brain requires about 130g of glucose per day to function).

Then you have studies that predominantly use either percentages or absolute numbers. Some studies may use 40% as an arbitrary number for low-carb diets, but researchers of low-carb studies claim that 40% is too high. Whatever the case may be, a low-carb can safely be defined as having an intake of 50-100g. I prefer to use absolute numbers instead of percentages since they give you more solid guidelines. For example, if you used percentages, you would get different numbers depending on how many calories one eats.

For the sake of discussion, let’s say you want to get into a ketogenic state by eating 50g of carbs per day.

If you were a 2000-calorie diet, 10% would be 50g of carbs (50 * 4 = 200 kcals; 2000/200 = 10%)

But if you were on a 4000-calorie diet, 10% would be 100g of carbs, enough to knock you out of ketosis.

Instead, you can just say you want to eat 50g of carbs, regardless of what your calorie intake may be to get into ketosis.

Breakdown of carbohydrate intake:

  • 0% or 0: no carb
  • 20-50g: very-low carb (if high-fat, this is considered a ketogenic diet)
  • 50-75g: low carb
  • 75-150: moderate carb
  • 150-225: moderate to high carb
  • 225+: high carb

Before we move on, let me make clear that I am a fan of lower-carbohydrate intakes. But what I mean by lower is that my plans are lower than what public health agencies and authorities suggest. The United States Department of Agriculture (USDA) nutrition guidelines suggest up 45-65% of daily calories to be in the form of carbohydrates. Of course, this highly depends on the individual, but suffice it to say that a vast majority of people would benefit from a lower carb intake than what they’re currently eating.

Source 

Benefits of lower-carb plans

This part is going to be short. I cannot help but be a bit biased toward carb intake on the lower side, and as such I realize that there are more benefits to lower-carb diets than consequences for a vast majority of people. When I refer to lower-carbs, I mean anything under 45%, which is the minimal that health authorities recommend.

In the literature,  lower-carb plans have been shown to:

  • Improve fat-loss at a quicker rate than low-fat/high-carb diets (Shai; Yancy; Gow; Gardner)
    • Some studies show that low-carb diets induce almost double the amount of weight loss as high-carb diets in the same time frame
  • Retention of lean body mass (muscle) better than conventional diets (Volek, 2002; Volek 2004; Miyashita)
  • Decrease risk factors and improve health biomarkers of certain cancers (Sedlacek; Ho)
  • Improve blood levels of inflammatory markers and endothelial/vascular function (Rajaje; Mah)
  • Improve insulin sensitivity (Blouet; Volek) and decreases levels of circulating insulin, which reduces risk of diabetes (Kodama; Demol)
  • Improve lipid profile (LDL, HDL, TG, total cholesterol ratio) thereby improving Metabolic Syndrome risk factors (Hu; LeCheminant; Sharman) compared to high-carb diets, which worsen diabetic complications and cardiovascular risk (Chen)
  • Superior glycaemic control compared to a low-fat/high-carb diet (Guldbrand)
  • More favorable impact on low-grade (chronic) inflammation compared to a low-fat diet (Jonasson)
  • Improves levels of leptin, which is considered the fat-burning hormone (Llanos)
  • In terms of athletic performance, too high of carb (above 5g per pound of bodyweight) intakes do not seem to confer additional benefits compared to moderate carb intake (Sherman)
  • Naturally lowers overall daily caloric intake by improving satiety (Wycherley; Bravata)

The last point is probably the most important point in this whole low-carb paradigm. Although many studies show that low-carb diets reduce weight, over half of them actually admitted that subjects lost more weight because they ate less due to satiety, which leads to less food intake. Translation: lower total calorie intake.

When talking about low-carbohydrate diets, you can’t ignore the impact that carbohydrates have on athletic performance. Most of the literature shows, without a shadow of a doubt, that high-carb diets outperform low-carb diets when it comes to athletic performance. But in the past ten years or so, low-carb gurus such as Mark Sisson, Robb Wolff, Stephen Phinney, and Jeff Volek have been proposing that a low-carb diet with high fat not only as effective as higher carb plans, but they also improve longevity, health, and body composition. If you need proof, look no further than some elite level athletes:

  • Professional cyclist, Dave Zabriskie
  • Ultramarathon runner, Timothy Olson
  • Triathlete Simon Whitfield
  • Winter Olympics pursuit event winner, Bjoern Ferry

Compared to high-carb plan athletes, low-carb athletes are much fewer in numbers. Whether their success is due to their diet or their insane genetics and training routine is still up for debate. One thing for sure is that low-carb diets DO work for some elite level athletes.

People who may benefit from low-carb plans:

  • Sedentary to moderately active people
  • Those with Metabolic Syndrome (overweight or obese; high lipids; impaired insulin sensitivity; high fasting blood sugars; high blood pressure)
  • Those with a history of high-carb plans
  • Those who are pre-contest (need to decrease carbs to improve appearance)

*** A little aside about fructose

Fructose, which is the sugar found in abundance in fruits, is primarily metabolized in the liver. The enzyme which catalyzes fructose metabolism is made in the liver. People say that fructose is an unnecessary component of an eating plan. Sure, it may be unnecessary… if you want to live like a zombie. Fructose is preferentially converted to glycogen in the liver so it can be used later, namely to keep your blood sugars under control. When you’re low-carbin’ it, this is important. Additionally, fructose is more efficient at supplying a constant stream of sugar to working muscles during exercise (Rizakalla).

After you eat fructose, it gets shuttled to the liver for processing. Unlike fructose, glucose and galactose act quicker, 30-45 minutes after ingestion. This is why all the holy Godmothers praise fructose as the next sweet savior, since it doesn’t increase blood sugar and keeps insulin levels down. Agave nectar, anyone? Now a low-carb plan will naturally dictate a decrease in fructose consumption because it decreases overall carbohydrate sources. Why is fructose consumption an important topic?

On average, the liver can only process 50g of fructose per day (Sun). This is equivalent to 24 ounces of high-fructose corn syrup sweetened soda, or 4 fruits per day. And what happens after you eat more fructose than your liver can handle? Since fructose is a nutrient just like many of the other things we eat, it’s quite plausible to theorize that bad things happen if you eat too much fructose. In 2002, a study released in the American Journal of Clinical Nutrition sent ripples through the nutrition world and raised a serious handful of eyebrows. In it, they concluded this:

“Fructose, compared with glucose, is preferentially metabolized to lipid in the liver. Fructose consumption induces insulin resistance, impaired glucose tolerance, hyperinsulinemia, hypertriacylglycerolemia, and hypertension in animal models” (Elliott).

However, in this particular study, the researchers were focusing on the additional sugars and sugar derivatives, like high-fructose corn syrup, and not the fructose found in plant foods. On top of that, they used animal models and used non-physiological doses, or doses that are unrealistic to humans in terms of their bodyweight. Later research come out trying to figure out if fructose consumption really was linked to insulin resistance and all that jazz. While the above study used animal models, studies refuting negative consequences of normal fructose consumption were based on epidemiological data. These data support that fructose levels 100g per day had no negative effect on bodyweight (Rizkalla).

Unfortunately, many people who were ill-informed and with bad intentions took this fructose conjecture and ran with it. Even to this day, people run with it. While I don’t believe fructose is something you should be alarmed about if you don’t drink sodas and eat sh*t, you shouldn’t necessarily go hog-wild on it, either. Moderation, folks.

Not the same as…

Back to our main program…

Drawbacks of low-carb plans

Let’s preface this portion with me stating that low-carb plans, in my eyes, are plans that state you should eat less than 75g of carbs per day. 

Although low-carb diets have been shown to improve glycemic control, weight-loss, and lipid profile in the short-term (within a couple of weeks), most of the benefits diminish after a year and the diet is quite comparable to its higher carb counterpart when controlled for calories. A massive review and meta-analysis published this year looked at how well low-carbohydrates fared against balanced diets matched for calories. They found that over time, balanced diets (40% carbs, 30% protein, 30% fat) were almost as effective as low-carb diets in almost all parameters, although low carb diets were more effective at reducing triglycerides, improving lipid panels, and improving insulin concentrations (Naude, 2014).

Carbohydrates are required for intense activity. If you have ever tried to train on a low-carb diet, then you don’t even need to defer to scientific studies. For example, I will use the Paleo framework as an example here. Paleo does a good job at being extremely vague at how many carbohydrates you should consume per day. However, over time, the more fanatical and active Paleo-ites, Crossfitters, began to recognize the benefits of carbohydrates for athletic performance. From the Crossfit website:

Carbohydrates should be predominantly low-glycemic and account for about 40% of your total caloric load” (Crossfit.com). I don’t recall where I saw this–it was a few years ago–but someone interviewed competitors from the CrossFit games, asking them about their diet and whether they adhered to a Paleo diet. If my memory serves me correctly, not a single one of the top competitors adhered to a strict Paleo diet: they drank buku amounts of milk. 

Rich Froning: not getting by eating 2-3 sweet potatoes a day. Source

The example above is Rich Froning, one of the best CrossFit athletes to have ever competed and is a genetic beast. He didn’t start his career in CrossFit, either; it was in powerlifting. I will admit that this guy kicks ass and takes names, but don’t think for a second that all he eats per day are a couple of sweet potatoes. To build a physique and acquire conditioning like him takes years of hard, consistent work, not the fly-by-night plan that promises a six-pack in 4 weeks. By eating a diet with reduced carbs, you may be able to work towards his physique, but his athletic performance is a whole different matter.

Now in the literature, research shows that too little carbohydrates depletes liver glycogen, which can lead to hypoglycemia (low blood sugar) and subsequent decline in athletic performance (Costill; ADA). With too little carbohydrates, you may ‘bonk’, which is the term described when the liver cannot maintain blood sugar at the pace that sugar is being used during exercise. This is especially true in endurance sports such as marathon running and cycling, where you are working at above 75% of your maximum heart rate for hours and your body relies on carbohydrates for fuel. Plus, good luck finding many low-carb Olympic athletes standing on the podium. I listed a few athletes up top, but they are far from the rule.

Another major potential issue of going too low in carbs for too long is the dysregulation of thyroid hormones. The thyroid gland produces hormones that are specially responsible for regulating metabolic rate. Carbohydrates are known to induce increases in metabolic rate because they stimulate the increase of thyroid hormones. Connecting the dots, we see that if you restrict carbs for too long, you run the risk of decreasing metabolic rate via decrease in thyroid hormones (Muller; Danforth). There is even some talk on low-carb forums where people have unexpectedly get diagnosed with hypothyroidism.

The last drawback of low-carb diets I will talk about in this post is the ability of long-term low-carb diets to increase levels of cortisol and decrease levels of testosterone. Some of the literature has shown that staying low-carb for too long throws the balance of androgens and cortisol off-balance, especially in those who are participating in high-intense activities, such as ice hockey (Anderson; Tegelman). For men, this could pose a problem.

Carbohydrates trigger the release of insulin from the pancreas in healthy and most sick individuals (unless you’re type 1 diabetic, in which you lack insulin). Common sense dictates that insulin is a requirement for survival. This is pretty much a fact and not many people argue about it, even the low-carb gurus. But what many people overlook is that insulin is also anti-inflammatory. Low-carb experts often claim that insulin is the reason that people get fat. No, I argue, that is not true. Eating too much is the main reason people get fat. Insulin is just there to clear sugar from the blood, which is toxic if levels get and stay high (of course, a carb-based diet will drive up insulin levels in the absence of intense physical activity). Having high blood sugars is indicative of a state of inflammation and without insulin to clear it, you will heal slower, get infected easier, and die quicker. In short, you need insulin. So although eating less carbohydrates decrease insulin production, chronic use of low-carb plans may delay wound healing and increase risk of infection (Hyun).

Carbs, in the form of starch, is necessary for optimal health and gut function. Your microbiota, or the gut living in your gastrointestinal tract, require starch and fiber to survive and grow, and in return, giving you  health (Chassard; Sonnenburg).

People who should be more cautious of low-carb plans:

  • Very active athletes
  • Athletes with high muscle mass
  • Those with a history of very-low carbohydrate diets
  • Those who have terrible control over their sweet tooth

Although the above are drawbacks of low-carb plans, especially the last two, don’t be deterred from undertaking low-carb diets in a sensible way. One study is not enough to prove a causal relationship. Also keep in mind that the short-term decreases in thyroid hormone and increases in cortisol may not translate to you and do not mean that low-carb diets are inherently bad . Remember that low-carb diets have been and continue to be used with great success to get sick people healthier. It’s just that for athletic performance, you want to be more cautious.

Should you get low?


Your carbs probably shouldn’t be as low as this car (source)

Low-carb and high-carb plans definitely have their place. They are each part of the continuum and depending on your circumstances, each can be warranted. For example, low-carb plans may be more suitable if you have a severely deranged metabolism, such as high trigs, abnormal lipid panels, and God knows what else. If you’re looking for a quick and safe way to get your health back in line, low-carb plans can be highly effective.

But as stated above, low-carb diets work their weight-loss magic because they are better at keeping you full, which leads to early satiety. For example, in a conference in Atlanta in 2013, researchers presented a study that measured appetite and hunger ratings after two isocaloric breakfasts: one rich in protein/low in carbs and one with low protein/high carbs. A breakfast with 30-39g of protein and low in carbs was better at curbing hunger than a high carb breakfast, despite being the same number of calories.

Better hunger stomping means less appetite which means less calories. In spite of that, low-carb plans are not all that much better for absolute weight-loss compared to higher-carb diets as long as energy intake is accounted for. Essentially, if you eat less than you need to maintain your body weight, you will lose some weight regardless of how many carbs you eat. This was sufficiently demonstrated by a professor from an Iowa university a few years where he ate a diet consisting mainly of donuts, cakes, and cookies. However, low-carb diets have been shown to be superior in terms of health biomarkers and the aforementioned hunger control. Better hunger control probably means better dietary adherence, which is an all-important factor determining efficacy of diets.

Low-carb plans are not without their consequences. The key in all of this is making smart food decisions and engaging in a good exercise program, not your typical broscience bull crap.

How I do things

Liebman’s review on optimal intake ranges for carbs is a very good starting place for many people, and is the range I stick to for most of my and my clients’ activities. Unless you are an uber-active endurance athlete or blessed with God-like genetics, then you are probably better off wading in the swamp of 26-44% of carbohydrates per day. We can turn those figures to 20-40% to make things a bit easier. Having carbs at these numbers eliminates the risk of running into low thyroid, leptin, and energy issues over the long haul.

Eating 20-40% of your carbs also regulate the necessity to meet  exercise needs. This is especially important if you want to build more muscle, since the insulin released from eating carbohydrates is potent anabolic stuff (and that’s why constantly high insulin levels lead to fat gain, since fat storage and creation is an anabolic process). If you want to look at this in terms of numbers, then I suggest staying in the range of 75-150g of carbs per day. You can run the lower number on your non-training days and closer to 150g on your training days if you’re fat and/or sick. This number may register higher if you engage in more physical activity.

If you want to do a low or very-low carb diet, be my guest. I am not here to discourage you from doing so. You may very well be someone who responds positively to a lower-carb diet. It’s quite true that many people have anecdotal accounts of low-carb plans doing wonders for them. When I reached 5% bodyfat, I was on a low-carb/moderate fat/high protein diet. When my wife and I were preparing for our two previous powerlifting competitions, we used low-carb plans to decrease body fat while making sure we don’t lose strength and muscle. For people who are trying to lose fat and lose it fast, short-term stints with a low-carb plan might be the ticket that gets you to paradise.

Since adherence is usually the thing that separates champions from losers, you want to make sure you pick a plan, stick with it, and make modifications later when you are done. Low-carb adherence is no exception; sticking to it may not be any easier than sticking to a high-carb plan, though it may depending on your disposition towards food. If you are on a low-carb diet and want to increase your carbohydrates, whether it’s after a powerlifting competition or a photo shoot, then start by slowing adding 20g or so of carbs per day until you reach a level where your mood, performance, and body composition either stabilizes or improves.

Setting up an efficient plan:

  • Carbohydrates: 20-40% or 75-150g per day
  • Fat: 30-40% or 0.5g of your target bodyweight per day
  • Protein: 30-40% or 1.0g of your target bodyweight per day

Bottom line

Calories are your main priority. In a vast majority of the studies mentioned in this article, the researchers mentioned whether or not the diets were matched in calories. And in all of the studies matching calories but differing macronutrient composition, weight-loss was almost identical. If they were different, we are looking at 2-4 pound difference in a span of 12 weeks. Nothing to really split hairs about.

The shining light about low-carb plans is their ability to improve satiety, leading to possible better adherence to eating plans and moods. Lower-carb diets are also superior to high carb diets in terms of health improvements, especially in the short-term (6-12 months). Effects persist as long as people stay on the diet.

A low-carb plan cannot suit everyone’s needs and goals. Start with those numbers based off of the evidence and modify them to suit your lifestyle.

As always, your feedback is appreciated.

Live life strong,

David

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