Carbohydrates and why you need them

Intro from Josh: I am delighted to introduce Daniel Cuda to the blog, a certified nutrition counseller who has some fantastic science-backed insight to share on a number of important topics. Over to you, Daniel...

One of the most popular and recommended tips to shed body fat is to cut out, or at least lower, your carbohydrate intake. The guy or gal on the fitness magazine said so, thus, it must be true!

In reality, carbohydrates are given a bad rep for absolutely no reason. Carbs are in fact an essential part of a healthy diet, and (unless you have a medical reason that dictates otherwise) here are three reasons why you need to eat them.

1) Carbs are fuel

Carbs are not just fuel, but are your body’s preferred and primary source of fuel. Your central nervous system (your brain and nerve tissues) rely on carbohydrates. And your brain itself requires approximately 100g of carbs every day1 to function optimally.

Essential brain functions such as working memory and learning are closely linked to how efficiently your body uses glucose2, which is the fuel our body obtains when we break down carbohydrates. Without enough glucose, these brain functions become compromised and neurones cannot fire optimally.

Besides our brain’s main fuel source, carbs are also our high octane fuel for exercise! Carbohydrates are broken down at much higher rates and much more efficiently then fat and, thus, our body relies on them for higher intensity exercise such as sports, weight lifting, bodyweight exercises, circuits, running, and much more. These carbs are stored in the muscles as glycogen, which is used as the energy source for muscular contractions.

When your body does not have enough stored glycogen when you want to perform these activities, it will start tearing down protein (i.e. your muscles) as protein is also broken down at much higher efficiencies then fat3. And protein breakdown is the last thing you want as this will ultimately lead to loss in strength and muscle mass!

So, if you're looking to optimise your brain function and your athletic performance, carbohydrates are your friend!

2) Carbs are not easily stored as fat

This is the one that will probably shock the majority of people reading this! Most people assume that carbohydrates are the evil culprit to all their weight gain. That is what has been advertised for years and is how most of the fad diets we know today were created. But when you take a look at the physiology, the results may surprise you.

Your body stores carbs as fat through a process called de novo lipogenesis; a very inefficient and difficult process. When you overeat on carbohydrates AND you are above your caloric requirements for the day, your body stores fat. However, it is not from those carbohydrate molecules turning into fat themselves. Instead, your body preferentially burns those carbs whilst storing extra calories from fat (not carbs) in your adipose tissue. It is much easier for the body to store fat as fat then to convert carbs into fat. Your body does not need to burn much of that dietary fat and will therefore store it1.

An easier way to understand it is that your body will actually burn those extra carbohydrates, but would have no need to burn much of the fat you ingested throughout the day as energy due to the ample amount of available energy from carbohydrates. This is again because carbs are not easily converted into fat from a physiological standpoint. Thus, your body will burn through those carbohydrates and store a lot of that fat simply because it is easier to store fat as fat. Even then, you would still have to of overeaten more calories then what your body needs in that day to even gain weight in the first place. Thus, it is much more accurate to say you are gaining weight because you are overeating rather than because you are eating carbohydrates.

3) Carbs are important for your health!

This is, at least to me, the most important reason to NOT cut carbohydrates from your diet. Carb sources like fruits, vegetables, legumes and grains offer a wide variety of essential nutrients to the body. These inlcude vitamins, minerals, and an immense source of phytonutrients that are pretty much absent in meats and fats. These are essential for your health, your longevity and your overall sense of wellbeing.

These essential micronutrients are found in rich concentrations in foods such as potatoes, sweet potatoes, oatmeal, fruit, vegetables, amaranth, quinoa, squash, beetroot... the list goes on. Your body uses these micronutrients as the building blocks for your cells to function optimally. Without them, illness is almost inevitable, and deficiencies are certain.

Your body needs these micronutrients to survive which is why you could probably eat a dozen donuts (nearly absent of any micronutrient value), but could not eat more than a few apples at any time. Your body is saturated with important nutrients with the latter and, thus, does not require much more food.

These important nutrients are the number one reason not to avoid carbs, and also the key reason why the quality of the carbohydrates you consume is incredibly important.

Thanks for reading!

Sources:

1) Burke, L., & Deakin, V. (n.d.). Clinical Sports Nutrition (5th ed.). McGraw-Hill Education (Australia).

2) http://neuro.hms.harvard.edu/harvard-mahoney-neuroscience-institute/brain-newsletter/and-brain-series/sugar-and-brain

3) Tiidus, P., Tupling, A.R., Houston, M. (2012). Biochemistry Primer for Exercise Science (4th ed.). Human Kinetics.

Comments (3)

By 1 posted on February 26, 2018

1

By Tom posted on September 04, 2017

Olivier,

The body can breakdown various substrates and metabolic byproducts for glucose. It evolved to do this for obvious reasons.

Just because the brain can utilise ketones does not negate the need for glucose, in fact the brain consumes ~6mg of glucose per 100g brain tissue per minute. A typical brain is about ~1.3kg.

The metabolic processes for converting glucose into triglycerides to be stored is highly inefficient. In fact it nearly never happens, and when it does happen it is predominantly stored as liver fat. When insulin is high you increase the amount of glucose you metabolise and store as glycogen whilst preventing fatty acids from being released from and utilised for energy. Unless you are eating a zero fat high carbohydrate diet all dietary fat in your meals is stored, not the carbohydrate which is metabolised for energy whilst insulin is high. Insulin is the signal that glucose is in ready supply so your body increases the rate by which it metabolises glucose.

“For instance, two studies found that 50% carbohydrate overfeeding increased carbohydrate oxidation about two-fold to match carbohydrate intake, and this change was accompanied by an increase in energy expenditure, whereas 50% fat overfeeding increased fat oxidation rates by only ~20% with no change in energy expenditure.” (Peterson, 2017)

I have listed some bullet points on De Novo Lipogenesis on my article here: http://useful.coach/articles/carbohydrate-climbing-performance/#carbohydrate-overfeeding-and-de-novo-lipogensis

I agree that muscle protein breakdown is not a major argument for the sake of carbohydrate, but muscle protein breakdown is halted by an increase in insulin. So just a small insulin raising snack halts muscle protein breakdown.

It is worth looking at the “Satiety Index” where you see boiled white potatoes are the highest. Satiety is more related to palatability and processing. Fruits are nearly twice as satisfying than white bread. Also adding fat to a meal does not increase it’s satiety, protein does. Plain carbohydrate is satisfying, plain fat is satisfying, mix them together and they increase the likelihood of overeating.

Insulin is a signal to the brain/nervous system/body that there is surplus energy. Insulin in the brain and liver reduces food intake.

The issue is that when we talk about carbohydrate being a problem, we are talking about hyperpalatable high energy dense foods which are in the majority either liquid sugar (drinks) or combined with fat (snacks). The reason people can consume a whole pizza, litre of cola and still snack on chips is not because of insulin, but rather because they are delicious and light up the brains reward system whilst suppressing the energy feedback loop. No one overeats apples.

By olivier posted on August 15, 2017

You should be ashamed of yourself – writing nonsense that is biochemically inaccurate.

Physiologically the body needs zero carbs as it synthesizes what little it needs – and the correct amount is 30g per day for the brain once the body is burning fat for fuel. The brain is perfectly happy fueling itself off of ketones for most of its energy. And so are muscles.

You completely miss the role of hormones on the body’s fuel choice – ie insulin vs glucagon. And completely miss that if you’re storing fat from carbs (ie insulin is high) your cells cannot access stored fat for fuel (glucagon production in the pancreas is shut down), thus creating a one way street to getting fat.

The body does need proteins for the essential aminos in them but excess dietary protein will be converted to glucose. Note this is not from muscle. In fact, many studies on fasting have shown that it takes weeks for the body to begin metabolizing muscle in a fasted state. The absence of carbs has zero to do with the body’s metabolism of its own muscle tissue.

The ONLY part I somewhat agree with you on is elite athletes – those in highly anaerobic sports probably do need some complex carbs as the metabolism of fat into energy is too slow. But most people reading your junk won’t be elite athletes in anaerobic sports.

Apples giving high satiety ? Proteins and fats yes. Carbs no way. The insulin cycle makes you hungry again – that’s satiety?

Get your facts straight. And do some basic research before writing garbage that will poison people.

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