Carbohydrates ‘Carbs’ – Friend, Foe, or Both?

In contrast to the widely acclaimed macronutrient protein, carbohydrates (carbs) tend to be misunderstood and frequently maligned.

We have a huge array of ‘low carb’ diets, food products and supplements. Big alcohol cashes in on the carb-bashing to sell a range of ‘low carb’ beers, wines, and alcopops.

But are alcoholic drinks and foods really ‘healthier’ if they’re ‘low carb’? And what does ‘low carb’ actually mean?

Without actually defining it, marketers seem to have convinced us that ‘low carb’ is unquestionably good.

Conversely, if we’re to believe that ‘low carb’ is good and healthy we’re left with a logical assumption; carbs must be bad.

Yet carbohydrates tend to be our major source of energy. Our National Nutrition Guidelines recommend eating plenty of carbohydrate-rich foods.

This apparent paradox results in people holding a series of apparently logical, yet flawed beliefs such as:

• The national guidelines are irrelevant and can’t be trusted
• We shouldn’t eat too much fruit because it’s full of sugar
• Carbs are fattening – you should avoid bread, potatoes, and pasta…

However, could it be that carbohydrates are both friend and foe? Could they be essential to good health and function whilst also being a problem?

Answering such questions requires us to develop our general understanding of carbohydrates. Hence, in this article, we’ll discuss:

• What carbohydrates are and what foods provide them
• The role of carbohydrates and dietary fibre
• New Zealand’s pattern of carbohydrate intake
• Whether athletes need to carbo-load
• The influence of carbohydrates on bodyweight and weight loss.

What are carbohydrates and what foods provide them?

Because nutrition is fundamental to human health, we cover it in detail in our Personal Trainer and Weight Management courses.

We highlight a crucial fact – carbs are not foods per se. Rather, they are nutrients found within foods. It’s the food itself that determines whether or not it’s healthy.

For example, fresh fruit and fruit-flavored sweets are both high in carbohydrates. The fruits are healthy, the sweets aren’t.

At a molecular level, all carbohydrates are compounds made from just three elements: carbon, hydrogen, and oxygen. Hence, carbohydrates are also referred to as ‘CHO’.

Carbs differ according to their physical and chemical structure, and their effect on the body. At a basic level, carbohydrates are defined as simple or complex.

Academically, carbs are divided into four groups based on their number of ‘saccharides’ (sugar building blocks):

• Monosaccharides – one building block
• Disaccharides – two building blocks
• Oligosaccharides – ‘oligo’ = a few [building blocks]
• Polysaccharides – ‘poly’ = many [building blocks].

Mono- and di-saccharides are small, easily digested molecules. In contrast, polysaccharides, known as long-chain carbohydrates, are more structurally complex and therefore harder to digest.

Polysaccharides are further divided into Starch and Non-Starch Polysaccharides (NSPs). Starch consists of multiple glucose molecules (the most abundant monosaccharide) and is found in the foods we often associate with carbohydrates: bread, potatoes, rice, and pasta.

NSPs are found in the cell walls of plants. They make up the main component of dietary fibre which we’ll discuss in greater depth shortly. NSPs avoid digestion. They pass through the digestive tract where they are only partially broken down via a process known as fermentation.

Ultimately, carbohydrates are synthesised (made) by plants from water and CO2 using the suns energy. As such, it’s plant foods that provide us with rich, healthy sources of carbohydrates: all fruits, vegetables, nuts, grains, seeds, and legumes.

Is dietary fibre an underrated super-nutrient?

Depending on where you live in the world, carbs make up 40-80% of Total Energy Intake (TEI). Relative to other macronutrients, higher carbohydrate (CHO) consumption is often observed in:

• Many Asian countries where rice is a staple food
• The Middle East and North Africa where bread is a staple
• European countries such as Italy and Spain where the Mediterranean diet is popular.

It’s notable that the high CHO consumption in these countries is not associated with obesity and type 2 diabetes, as the Western diet is. To understand why this is, it’s essential to understand to the role of dietary fibre.

Chemically speaking, fibre is a carbohydrate because it consists mostly of NSPs. Making up the outer layer of plants, fibre provides them with shape and structure.

In humans, the primary role of fibre is to keep the digestive system healthy and protect us from: constipation, bowel cancer, irritable bowel syndrome and haemorrhoids, amongst other things.

Importantly, fibre-rich foods pass through our digestive system without the fibre being digested. In doing so fibre:

1. Slows the process of digestion thus providing a sustained release of energy over a longer time period
2. Provides bulk which helps us to feel full, without providing calories.

Consequently, people with higher fibre intakes tend to eat less over time and have much healthier bowels.

Dietary fibre really is an unheralded super-nutrient.

In comparison to the countries mentioned earlier, our CHO intake tends to come from heavily or ‘ultra-processed’ breads and cereals.

During processing, much, if not all of the fibre is removed. You see this in a loaf of ultra-processed white as opposed to whole-grain bread. The seeds and grains aren’t visible in the white bread because the fibre has been removed. As has much of the nutritional value.

Additionally, our general consumption of:

• High fibre fruit and vegetables is poor
• Manufactured drinks and snacks with an abundance of ‘free sugars’ is higher than recommended.

(*Note: The World Health Organisation (WHO) defines free sugars as: all mono- and di-saccharides added to foods by the manufacturer, cook, or consumer, plus sugars naturally present in honey, syrups, and fruit juices. Ideally, less than 5% of TEI should come from free sugars according to the WHO.)

During the process of digestion all carbohydrate foods (with the exception of NSPs) are broken down into glucose. This glucose, or more specifically, ‘blood glucose’ at this stage is either:

• Used as an immediate energy source, or
• Converted into glycogen and stored in the muscles and liver for future use, or
• Converted into and stored as bodyfat (if the limited glycogen stores are already full).

Without dietary fibre to slow the digestion process, carbohydrate-rich foods are rapidly digested. This results in a rapid supply of energy. Because most of this energy isn’t required immediately, much of it is converted into fat for storage.

And because these foods are rapidly digested, we’re left feeling hungry again quickly. This usually results in us eating more to satisfy our hunger, and consequently, storing more bodyfat.

The kiwi diet, being a typical Western diet, can be improved significantly simply by adding more unprocessed, high fibre foods – fresh fruit, vegetables, and wholegrain products.

What does New Zealand’s carbohydrate intake look like?

As we’ve already indicated, the typical kiwi’s carbohydrate intake has room for improvement. It’s worth identifying exactly where the problems lie however, and the degree of those problems.

The Ministry of Health’s (MoH) Eating and Activity Guidelines recommend adults consume the following quantities of carbohydrate rich foods:

It’s worth noting that:

• The MoH recently increased the recommendations for vegetable consumption from 3 daily serves to 5-6
• For athletes and very physically active people, up to 3 additional daily serves per food group are recommended.

It’s also worth noting that the MoH definition of a serving size is significantly less than what most people assume. For example, the MoH defines 1 daily serve as:

• 1 medium tomato, apple, pear, orange, or banana
• ½ cup cooked or canned vegetables
• ½ medium potato or similar sized piece of kūmara, yam, or taro
• 1 cup of green leafy or raw salad vegetables
• 1 sandwich slice of wholegrain bread (not toast slice)
• 2 Weetbix
• ½ cup of cooked rice, pasta, noodles, or quinoa.

In terms of our actual intakes, the ministry’s National Health Survey data tells us that:

• Only 10% of adults eat the recommended amount of fruit and vegetables
• Vegetable consumption is worse amongst children than it is in adults!

Additionally, as we’ve previously indicated, our intake of breads and cereal products errs towards the heavily processed. And we tend to have a high consumption of snacks and drinks with lots of added sugar.

It’s clear that many of us are obtaining our carbohydrates from unhealthy as opposed to healthy food sources.

Carbs aren’t the problem per se – it’s the foods we’re getting them from which is the problem.

Carbs and weight loss – friend or foe?

Weight loss is big business. Really big business. Globally, the market for weight loss products and services was valued at 254.9 billion ($US) in 2021. Diets make up a major portion of this market, of which ‘low carb’ diets are particularly popular.

But what does the research say about such macronutrient-oriented diets?

In 2020 a meta-analysis [ref 1] investigated the effectiveness of different macronutrient patterns and popular diets. Almost 22,000 subjects were involved in the analysis which covered 121 different studies.

The analysis found that:

• Over six months, most macronutrient diets produced modest weight loss and improvements in cardiovascular risk factors
• At 12 months, weight loss diminished among all macronutrient patterns and popular diets
• At 12 months, the cardiovascular benefits disappeared for all interventions except the Mediterranean diet.

In 2022 another meta-analysis [ref 2] measured the effectiveness of low vs. balanced-carbohydrate diets in adults with overweight and obesity. Almost 7,000 subjects were included in the analysis that covered 61 studies.

The analysis found:

• Little to no difference in weight loss and changes in cardiovascular risk factors between the different diet types.

The authors made some valuable observations, namely that:

• Current dietary guidance allows for flexibility in the relative proportion of macronutrients, including a wide range of carbohydrate intakes
• Greater emphasis should be placed on quality over quantity of foods, and on total dietary patterns over single nutrients
• Due to the complex etiology of obesity, it is important to combine diet with other positive lifestyle and behavioural interventions to reduce weight and cardiovascular risk.

These observations mirror many of those covered in our Weight Management programme. Diets fail to produce sustainable results because they employ a ridiculously simplistic approach to addressing a complex, multi-factorial problem.

Do ‘athletes’ need to carbo-load?

As my mid-life crisis emerged in 2013, I decided to tackle the Coast to Coast (C2C) adventure race.

Because carbs are the bodies preferred energy source, its common lore that loading up on carbs is beneficial for endurance-oriented events such as the C2C. Especially as our carbohydrate stores (glycogen in the muscle and liver) are very limited.

I ‘attempted’ to adhere to the common lore.

My dietary intake increased; lots of ‘starchy carbs’ and stews to make sure I was getting amble energy as well as protein to rebuild the muscle my training was damaging.

On top of this, I added cans of creamed rice to try and maximise my carb stores. The first few cans went down OK, but progressively I struggled with them – they just weren’t that nice!

And trying to ingest them as a pre-event load was a mission. From memory, one can took almost 30-minutes to ingest and involved a significant effort to stifle numerous gags.

Should I have bothered with the creamed rice?

According to sports nutritionists Louise Burke and Vicky Deakin [ref 3], probably not.

Burke and Deakin suggest that when CHO is consumed during prolonged exercise, any effects of pre-exercise CHO intake on performance are negligible. It’s more important to refuel and maintain adequate hydration during the event than it is to pre-load.

They suggest that ‘the athlete’ should experiment with a variety of pre-event and general eating practices to find and fine-tune strategies that work for them. The general increase in consumption that accompanies an increase in training will most likely satisfy carbohydrate requirements.

So, athletes should consider practical aspects of nutrition such as:

• Gastrointestinal comfort
• Food likes and dislikes
• Food availability.

In short, if you don’t like a food and consuming it makes you gag, it’s not a good choice!

A Final Word

Yes, with the exception of NSPs, carbs are ultimately all sugars. This probably explains why they’re so easily maligned, and why ‘low carb’ is so popular.

But ‘sugar’ isn’t just ‘sucrose’, the 50-50 mix of one glucose and one fructose molecule that we add to our daily coffee. There are many different sugars which behave differently according to what surrounds them.

When surrounded by dietary fibre, water, and micronutrients, in real foods, ‘sugars’ are great sources of sustained energy along with other essential nutrients. Foods such as fresh fruit, vegetables, and wholegrain products provide this total package. As such they are ‘a friend’ to our health, well-being, and performance.

When the ‘total package’ is interfered with and foods become highly or ultra-processed, carbs become less of a friend.

At a personal level, we can actively work to increase our consumption of fruit, vegetables, and wholegrain products. We can encourage and support those we work with, and care about to do the same.

Unfortunately, our current food environment is a barrier for many kiwis.

In too many cases, the default options for carbohydrate-rich foods are the unhealthy ones: cheap white bread, sweets, fizzy drinks. By ‘default’, we’re talking about the option that is most accessible, affordable, and available.

To make healthy carbohydrate options the default, changes need to be made at a higher level. Local and international public health officials and organisations such as the WHO have recommended simple actions such as:

• Removing taxes (such as GST) from all fruit, vegetables, and wholegrain foods
• Adding consumption taxes to all products with ‘free sugars’
• Providing subsidies to fruit and vegetable growers to encourage affordable supply to domestic, rather than international markets.

In terms of public health, we’ve become an international laggard as evidenced by our alarmingly high rates of overweight, obesity and type 2 diabetes. As we show in our Weight Management diploma, individuals can’t be blamed for making poor choices when the default food options that pervade our living environments are the unhealthy ones.

Changing the food environment requires political action. We can start lobbying our ‘leaders’ for such changes to be made. And we can restrict our vote to only those who are serious about advancing such actions.

Changing our health and managing our weight in the long-term requires an approach that addresses our habits and focuses on food quality. Such an approach can be pursued while we wait for the politicians to catch-up.

 

References

1. Ge et al. (2020). Comparison of dietary macronutrient patterns of 14 popular named dietary programmes for weight and cardiovascular risk factor reduction in adults: Systematic review and network meta-analysis of randomised trials. BMJ (Online). https://doi.org/10.1136/bmj.m696
2. Naude et al. (2022). Low‐carbohydrate versus balanced‐carbohydrate diets for reducing weight and cardiovascular risk. Cochrane Database of Systematic Reviews. https://doi.org/10.1002/14651858.CD013334.pub2
3. Burke and Deakin. (2017). Clinical Sports Nutrition (5th Ed), Chapter 12. Australia: McGraw Hill Education. https://www.booktopia.com.au/clinical-sports-nutrition-louise-burke/book/9781743073681.html