8 February 2019
CARBOHYDRATES EXPLAINED: WHAT YOU NEED TO KNOW
I know what you’re thinking, you don’t need carbohydrates to be explained to you. Your Aunt Janice already spent over an hour doing that at the last family gathering. You heard all about how much weight she’s lost and how healthy she feels after cutting out carbohydrates and sugar… All while she sat there and…
I know what you’re thinking, you don’t need carbohydrates to be explained to you.
Your Aunt Janice already spent over an hour doing that at the last family gathering.
You heard all about how much weight she’s lost and how healthy she feels after cutting out carbohydrates and sugar…
All while she sat there and guzzled down here 4th glass of red.
In all seriousness though, carbohydrates are a hot topic and they have been for decades! Every man and his dog has an opinion on them.
And today, you’re going to hear mine!
Nah, I’m just messing with you.
Today, my aim is to discuss the general consensus on carbohydrates, as it is understood by and accepted within the scientific community.
A consensus mind you, that has been reached after decades of research, hundreds of studies and the subsequent meta-analyses (a study that looks at trends of multiple scientific studies – the gold standard).
But hey, you can believe Aunt Janice if you like…
Carbohydrates, or CHO as they are often abbreviated as, in reference to their chemical structure (for Carbon, Hydrogen and Oxygen) have many roles and uses in the body, however their primary purpose is energetic.
Unlike protein and fats, which provide essential amino- and fatty-acids respectively, carbohydrates are NOT an essential nutrient.
Essential referring to the body’s inability to create sufficient amounts of them on it’s own accord, and thus they must be consumed in the diet.
Carbohydrates DO NOT fall into this category.
Generally speaking, for the demands of everyday life, the body can produce adequate amounts of carbohydrates on it’s own.
In some circumstances, such as high-intensity exercise, when energy needs are higher and more carbohydrates are required, they may be considered essential in order for supply to match demand.
Therefore carbohydrates can be considered a conditionally essential nutrient.
Just because carbohydrates (along with many other nutrients) aren’t classified strictly as essential nutrients, it does not mean that they aren’t essential for life and survival. It just means that the body can convert or create them from other nutrients and it isn’t essential to consume certain amounts through the diet.
I will now take this moment to point out however, that just because something isn’t essential, doesn’t mean that it’s not a good idea to consume it. Within the context of nutrition, there is often a large discrepancy between enough, and optimal.
Many nutrients that aren’t required in the body for life and survival, can still have very large health and or performance benefits.
Carbohydrates definitely fall into that category!
With that out of the way, I will now explain what occurs when you do eat carbohydrates and then we will finish with a discussion on how many you may potentially need to optimise your carbohydrate consumption based on your goals.
Carbohydrates: Delicious, then what..?
Once digestion has occurred, carbohydrates are stored in the body in the form of glycogen, for which there are two depository sites – the liver or muscle tissue.
Additionally, a small of amount of carbohydrates (~5-10 grams) can also be found at any one time, floating around in the blood in the form of blood glucose.
Now, you might be thinking, but what about carbohydrates being stored as fat?!
Well, that doesn’t exactly occur and and carbohydrate consumption doesn’t lead to immediate fat gain as many low-carb advocates seem to suggest.
Carbohydrates that aren’t stored as glycogen or utilised immediately for energy, can POTENTIALLY be converted into body-fat.
However, this requires additional metabolic processes (read: work) by the body in order to achieve this. The technical biochemistry term for this process is lipogenesis, which translates roughly to “the creation of fatty-acids from non-fat substrates”, such as glucose and amino acids.
BUT, there is no way that carbohydrates can just be immediately stored as body-fat. Fat is fat and carbs are carbs. That’s it. For carbs to be stored as fat, a conversion must occur.
Sounds like common sense right?
Well unfortunately, common sense isn’t something that’s always prevalent in the media and fitness community…. But I digress.
This then begs the questions, what can we do in order to prevent lipogenesis from occurring to a significant extent?
Simple, we limit our calorie and carbohydrate consumption to what we require and no more.
Too much of a good thing, becomes a bad thing.
As with anything, there is a point of diminishing returns. Even though carbohydrates do offer many health and performance benefits (discussed below), beyond a certain point, they just become additional calories, which can and does lead to fat gain.
Alternatively, even if calories are kept in check, by still consuming more carbohydrates than you require, you will have to reduce the amount of the other macronutrients that you are eating.
This could potentially mean that you are not consuming adequate amounts of protein and/or fat…
Both of which DO contain essential nutrients!
Benefits of Carbohydrates for Body-Composition
Before we begin, I must quickly define some terms.
Anabolism – The formation of larger, more complex molecules from smaller, simpler ones (hence anabolic steroids make you bigger). This is an energy requiring process.
Catabolism – The opposite of anabolism and is the breakdown of larger, more complex molecules to form smaller, simpler ones (this is what the Bro’s are referring to when they haven’t eaten for like 38 minutes and are worried about “going catabolic” and breaking down muscle tissue). This is an energy releasing process.
Now, back to the benefits of carbohydrates…
A response that occurs from ingesting carbohydrates, is the rise in anabolic processes and reduction of catabolic processes.This is largely, but not entirely, due to increased insulin secretion.
Insulin is a hormone that is secreted in response to elevated levels of glucose and amino acids in the blood. Insulin helps to shuttle nutrients into cells for use or storage (whether it be muscle or fat cells). This then increases anabolism and decreases catabolism activity within the cell in a very direct manner.
As individuals who are concerned with our body-composition, we should strive to utilise these benefits of carbohydrates.
With sufficient carbohydrate intake, we can prevent the deconstruction, as well as slightly promote the construction, of complex structures (muscle) in the body. By ensuring that adequate amounts of carbohydrates are readily available, the body will reduce the amount of energy it is producing from the breakdown of other molecules. Other molecules such as muscle proteins.
This can potentially occur as muscle proteins are broken down into amino acids, which can then be converted into glucose within the liver.
Although this is a thrifty evolutionary trait to ensure the brain and other internal organs receive the glucose they require for functioning in times of energy deprivation (such as dieting), it is counterproductive to our weight training efforts, as we are trying to increase the net-balance of muscle protein synthesis in comparison to breakdown, as this is how muscle is built (or at least maintained).
During anaerobic exercise (such as sprinting, lifting weights, playing sport and pretty much anything that isn’t walking ), carbohydrates are without a doubt the body’s preferred source of energy.
The reason that the body relies so heavily on carbohydrates during these times is because the breakdown of fat to form ATP (Adenosine Tri-Phosphate, which is cellular energy) is a much more time consuming process and requires certain amounts of oxygen to occur.
During exercise, when ATP/energy is required rapidly, if adequate carbohydrates are not available (typically coming from glycogen), exercise intensity must and WILL decrease. What this means in a practical sense is: less reps per set, slower sprint speeds and longer recovery between bouts of effort.
For those with performance or body-composition goals, this is a serious issue. If you cannot perform at or even near your maximum capabilities, the ability to create overload will be diminished and thus the stimulus for positive adaptations will be minimal to nonexistent.
Like the anabolic/anti-catabolic effects, this is another very direct way that carbohydrates contribute to helping us achieve our fitness goals.
The final way in which I wish to discuss the benefits of carbohydrates for physique and performance is the way in which they influence molecular signalling.
As we know, carbohydrates are stored in the body as glycogen, predominantly within the muscles and to a smaller extent, the liver. These along with our fat cells, are our fuel stores. As the body is an extremely comprehensive and complex machine, it actually has internal fuel gauges, which help to regulate energy.
There are many types of internal fuel gauges and they all strive to alter energy balance in a number of ways.
The one that I am going to discuss in reference to carbohydrates and physique enhancement is the AMPK/mTOR pathway. This will be slightly technical, however I will do my best to summarise the practical takeaways.
AMPK (5′-adenosine monophosphate-activated protein kinase) is an energy modulator which acts on a whole-body level, regulating food intake and energy expenditure in response to hormones and nutrient signalling.
Downstream of this is mTOR (mammalian target of rapamycin), which is an intracellular nutrient sensor and helps to regulate energy expenditure through its influence on protein synthesis, cell growth and metabolism.
In an attempt to present that more simply, when AMPK senses energy (ATP) levels are low, it will up-regulate catabolic process and begin “burning” whatever it can (fat or muscle) in order to satisfy energy requirements.
Conversely, when cellular ATP levels are high and the body recognises that there is sufficient energy available, AMPK activity is down-regulated and this signals for the up-regulation of mTOR.
Basically, this pathway is an anabolic-catabolic spectrum.
Both processes are always occurring at the same time, however the degree to which they are occurring changes and is determined by a number of variables. Many of which we can manipulate.
One of the key indicators of the body’s energy status to the AMPK/mTOR pathway, is glycogen levels. Lower glycogen levels will result in an up-regulation of AMPK and down-regulation of mTOR and vice-versa for higher glycogen levels.
This influence on molecular signalling, favouring anabolism over catabolism and striving to up-regulate mTOR as much as possible, can over time, lead to more muscle mass and a better physique.
Note: I must point out, that carbohydrates are not the only factor contributing to the benefits above. Carbohydrates do play a major role, however if you are familiar with nutritional hierarchy, you will know that calories are the primary nutritional concern. Regardless of carbohydrate intake, a chronic surplus of calories will result in higher insulin levels, favoured mTOR signalling over AMPK and higher cellular ATP levels, resulting in more energy and greater performance and recovery, compared to those experienced in a deficit.
It is not the aim of this article to dispute that. As we know, chronic energy status (deficit, maintenance, surplus) determines changes in body mass.
What I am hoping to convey in this article however, is that granted calorie status is equated and therefore changes in total body mass will equal as a result.
I suggest consuming a high (relative to your energy expenditure) carbohydrate diet, in order to try take advantage of the above benefits, as they likely will have favourable body-composition outcomes.
Presuming you are in an energy deficit, net-catabolism will always be higher than net-anabolism and you will lose mass/weight.
However, attempting minimise muscular catabolism and maximise muscular anabolism will likely result in a greater preservation of muscle mass and mean a greater percentage of weight-lost is fat.
I will admit that this is some what speculation on my behalf, as there is not a conclusive answer due to minimal direct research on the topic, but mechanistic research suggests this is the case. I haven’t just pulled these recommendations out of thin air and I do believe direct research will prove this to be the case in the future.
All or None: How Many Carbs?
Now that we’ve examined carbohydrate basics and why they are a good idea to consume for those with fitness goals, the next logical step is to discuss how many we should eat.
As I mentioned above, too much of a good thing is a bad thing and although there are many benefits to consuming carbohydrates, we must strive to control our consumption in order to minimise negative trade-offs.
We are aiming for adequate but not excessive.
An overconsumption of carbohydrates within a calorie-controlled diet will lead to inadequate amounts of essential amino- and fatty-acids being consumed. If calories are not controlled then an overconsumption of carbohydrates will contribute to excessive fat gain, resulting in decreased insulin sensitivity (more insulin is required to store the same amount of carbohydrates i.e. type-2 diabetes) as well as potentially poorer nutrient partitioning (the ratio of calories being stored in fat compared to muscle).
So, how do we determine how many carbohydrates we should be eating?
As carbohydrates are almost exclusively used for energetic purposes (which is largely determined by body-weight/size), workload relative to body-size is the most appropriate method in my opinion.
I will admit that other factors should be considered, such as preference, however the purpose of this article is discuss what is likely to be the most optimal approach. Preference can still be considered, but understand that moving away from optimal in order for preference (more or less carbs as dictated by you) will have trade-offs (less of the positive and/or more of the negative effects).
Per Day Recommendations:
Unless you are correctly implementing a ketogenic diet (which isn’t just low-carb), consuming at least 50g of carbohydrates per day is likely to be a good idea as it has been shown to reduce the need for the body to utilize amino-acids for gluconeogenesis and thus is likely to spare muscle-mass to a greater extent when dieting.
Inactive/Rest Day: 1-2g/kg
On days you are not working out and are remaining fairly sedentary, consuming 1-2g/kg should be a good intake to aim for. This allows for some carbohydrates to be consumed in order to fuel recovery and restorative processes, such as glycogen replenishment, yet not overdo it as once glycogen stores have been replenished, additional carbohydrates are at a far greater risk of being converted into body-fat.
Lower-Volume Training Day (deload/strength block): ~ 2-3g/kg
As volume is the largest contributor to carbohydrate utilisation/glycogen depletion, during phases of lowered training volume (but still higher than complete rest days) aiming for an intake of 2-3/kg should provide sufficient fuel to complete the prescribed amount of volume, without overdoing carbohydrates.
Higher-Volume Training Day (Hypertrophy block): 3-4/kg
During phases of high training volume, such as hypertrophy blocks (when both number of sets and reps per set should be higher in comparison to strength blocks), more carbohydrates must be consumed in order to ensure performance and recovery. Aiming for 3-4g/kg should provide the fuel to perform multiple high-repetition sets, per body part, as well as the raw material to adequately restore glycogen levels prior to the next high volume workout.
Now, no discussion about carbohydrates would be complete without discussing the effects of timing.
Although it was completely intentional however that this section was left until nearly the very end.
The role that timing plays on the outcome of results is negligible when compared to the influence of total daily/weekly carbohydrate intake, but admittedly still existent.
The simplest and most basic recommendation I can give in regards to timing of carbohydrates, is to bias them around your workout.
Consuming them before workouts will provide elevated blood glucose levels and energy to perform. Consuming carbohydrates after a workout will help to resynthesize glycogen, bias processes in the favour of anabolism over catabolism and also takes advantage of exercise-induced increases in insulin sensitivity and nutrient partitioning.
Intra-workout carbohydrates may also potentially be a good idea for those with high-volume workouts that take over an hour. After approximately 60 minutes of exercise, blood glucose levels begin to drop, which is why concentration and motivation tend to decline during longer workouts, as blood glucose is what is used to fuel the brain.
Finally, we come to sources of carbohydrates.
I left this till last as it really doesn’t play a large role in results and should pretty much be dictated by preference, provided some common sense is used.
Common sense being: A diet that is varied, predominantly “unrefined/unprocessed” and is centred around fruit and vegetables. This is pretty much going to cover all your nutritional needs. Barring some extreme circumstances.
Something to be noted here, is that your entire diet doesn’t have to be made up of “clean” foods.
Once vitamin and mineral requirements are met, excess will simply be excreted through urination (that’s why your pee goes that fluorescent yellow colour when you start taking that over-priced multivitamin).
There are no additional marks for exceeding nutrient requirements!
That about wraps it up for this rather lengthy article on the beloved macronutrient; carbs.
Carbohydrates role in the body is primarily energetic and is the preferred source of fuel for anaerobic exercise
Carbohydrates cannot be directly stored as fat, they must undergo conversion first and this will not occur to any large extent if calories are controlled.
They have multiple benefits for body-composition (anabolic/anti-catabolic properties, performance effects and molecular signalling).
Tailoring intake to energy needs is likely a good idea to optimise benefits vs. trade-offs.
Timing and source make minimal difference to results.