• Marcus Baxby

Are Carbs the Devil?

Updated: Jan 21, 2019

You may have heard carbohydrates being compared to the devil. A master of temptation, pulling at the strings of some deep primal desire that you know is wrong, but is almost impossible to resist. Sin incarnate, requiring saint-like virtuosity to resist it's clawed, potato-clutching grip.

Fortunately, this is just a fairytale, but it's one that has been perpetuated, particularly over the last ten years or so, and which persists in the minds of many in the general population.

Carbs have been demonised, just like fats before them [fats article coming soon], and the trend towards low-carb diets has been remarkable in recent years, all too often without any real reason. So let's set the record straight.

What is a carbohydrate

Walk up to the average person on the street and ask them to explain what a carbohydrate is, and most people wouldn't be able to do it. Which, considering we eat them every day, is pretty ridiculous.

So here goes: Carbohydrates are one of the three macronutrients (the others are fats [link to article] and protein [link to article]. As we've said before, all three are incredibly important.

Carbohydrates are large molecules consisting of carbon, oxygen and hydrogen, combined to form a saccharide (sugar group). The most simple carbohydrates, such as glucose and fructose, are monosaccharides (meaning they are a single sugar group and can’t be broken down any further).

Oligosacchirides consist of between 3 and 9 sacchirides joined together, while longer combinations (10+) of sacchirides are called polysaccharides.

The simplest sugars (monosaccharides) are the easiest and quickest for the body to digest. All other carbohydrates are broken down into monosaccharides before they are absorbed.

Once broken down and absorbed, the monosaccharides/ sugars go to the liver to fill energy stores. They then enter the bloodstream where they are transported to other cells in the body. Carbohydrates are the body's preferred source of energy, and are used by different body parts in different ways, including the brain, muscles, kidneys and liver.

Here are the principles when it comes to dietary carbohydrates for particular goals:

Fat Loss

At NewBee Nutrition, we prefer to focus on the fundamentals, not the fads [see our Core Principles]. Both low-fat diets and low-carb diets, when fat loss is the goal, are attempts to do one thing - reduce the overall calorie intake of a person's diet, in order to create the calorie deficit required to lose weight.

Let's get this straight from the outset, and reiterate one of our Core Principles - calories are the most important factor for fat loss. If you eat less than you burn, you will lose weight.

To assist in getting your calorie intake under control, protein is very useful - specifically for keeping you full for longer, and for ensuring you lose predominantly fat, rather than muscle.

Once you have your protein intake sorted, the rest of your calories can be made up of any combination of carbs and/or fats. As long as you are in a calorie deficit, you will lose weight!

This is THE principle behind fat loss, and is one that, unfortunately, the fitness industry often obscures behind marketing fads, diet teas, supplements and other such rubbish.

It is not necessary to cut out carbohydrates to lose fat.

When calories and protein are matched, there is no difference in fat loss, whether you choose to lower carbs or not. This has been shown in well-performed scientific studies time and time again [Golay et al (1996), Johnston et all (2006), Miyashita et al (2004), Hall et all (2015), Hall et al (2016), Kevin Hall's meta-analysis (2017)]

You may choose to lower carbohydrates in order to remain in your calorie deficit, and for many people, this is a useful tactic. For example, you could choose to have one or two low-carbohydrate meals per day, and to instead just eat protein and vegetables, with maybe a little fat. If you can stick to this, and this enables you to lose fat, then brilliant.

But bear in mind the principle - the reason you have lost fat is not because you have cut carbs. It's because you have found a sustainable way of creating a calorie deficit.

In terms of Fat Loss, some of the research seems to indicate an intake of between 1g and 3g per kg of body weight may be optimal, but again, this will all need to be in the context of an overall calorie intake.

Asian populations, for example, have high rice intakes, and these do not correspond to obesity levels. For the blogs about my travels in Asia, and my experiences with food, click on the links below. [Japan]

Sugar: Is a carb always a carb?

Ah, but 'what about sugar' I hear you say - surely eating sugar will stop me losing fat more than eating brown rice or quinoa?

First of all, as Martin MacDonald [link to IG] would say, the fact that the sentence above starts with the word 'surely' instantly means it is not actually based on anything. So let's look at what the evidence actually says.

As ever, the evidence-based fact is that calories, not the source of the carbohydrate, is the most important factor when it comes to fat loss. Sugar has been demonised more than any other type of food. This may sound like a broken record by now, but as long as you control your calorie intake on a consistent basis, and hit the requisite level of protein per day [see protein article to see how much], you will hit your fat loss goal.

Now, the difficulty is that most sugary foods are highly processed and high in calories. Haribo, for example, have over 300 calories per 100g (they are usually sold in 200g bags, and people don't often share them!). Sweets like this are pumped with an unnaturally high level of sugar, making them high in calories.

Also, the majority of other sugary foods are not just sugar - they are usually combined with fat, which not only makes them high in calories, but also makes them 'hyper-palattable', meaning that they are easy to over-eat. Think of cakes, chocolate, biscuits etc. Delicious?

Yes. High in calories? Yes. Can you just eat one? Maybe - but most people can't - one is never enough! This is because these sugar and fat combinations have been processed to be delicious and hyper-palattable [Article on the food environment coming soon].

This means that consuming these foods increases your overall calorie intake, making it much harder to stick to your calorie deficit for fat loss, especially when you don't have control over how much of them you eat.

That's not to say that you absolutely can't eat sugary foods and still lose or maintain your weight. You definitely can, and lots of people do.

In fact, complete restriction of a food, particularly one you really like, is probably not healthy from a physical or psychological point of view, since you are more likely to 'have a blow out' or 'cheat' when you have restricted something for a long time, which may ruin your overall calorie deficit, and create a poor relationship with certain foods, leading to poor eating habits in the long term.

So it is possible to have your sweets, and have your chocolate, but you must bear in mind their caloric content, and bear in mind that you will still need to be in an overall calorie deficit in order to lose fat - which, obviously, will be much harder if you are consuming high calorie foods that are difficult to stop eating!

Now, with full disclosure, there is some evidence to suggest that you may harvest slightly more energy by eating refined sugars, rather than whole food carbohydrate sources.

However, the difference is so small that it is not going to make much of a difference for most people who are controlling their calorie intake (incidentally, the largest extra calorie effect of refined sugars versus whole food carbs comes in overweight people who are in a calorie surplus - who are the people that, more than anyone, should probably start reducing their calories, and reducing their intake of high-calorie processed foods!).

At NewBee Nutrition, we advocate eating whole foods for the majority of your diet, and this goes for carbohydrates too. Think potatoes, sweet potatoes, pumpkin and squash, vegetables, whole grains and fruits. Not only are they generally lower in calories than highly processed carb sources, they contain fibre (link to insta post), vitamins and nutrients which are important for overall health, and are also much more satiating.

A potato, for example, is a food that is high in carbohydrates, but is also highly satiating (and if anyone tells you a potato doesn't count as a 'real food' or 'whole food', they are either misinformed or deliberately lying). Whole foods aren't crucial to fat loss, they just make it a whole lot easier to control your calorie intake.


As we've learned, fat loss is an energy dependent process - eat fewer calories than you burn, and you will lose fat, regardless of the source of those foods. Weight maintainence is an indicator of long-term health, so if a person is overweight, their first priority should be to lose excess body fat.

For long term health, the human body also needs certain vitamins and minerals (micronutrients) in order to keep vital bodily functions working like they should. These micronutrients are found in whole foods [link to Core Principles], so for health, the best sources of carbohydrates are whole foods - potatoes, whole grains, legumes, vegetables and fruit are what we mean here.

Whole foods also contain fibre, which aids digestion, and is crucial for gut health (see gut health article).

As we mentioned, this includes fruit, which has been caught up in the demonisation of sugar. People have realised, for example, that bananas are very high in sugar, and have therefore equated eating a medium size banana, with 20g of sugar, to eating a packet of Reese's peanut butter cups https://www.instagram.com/p/BmfVev0n5KZ/?hl=en&taken-by=thealanaragon, also containing 20g sugar (oh, and 220kcals, 117 of which are from fat - remember those fat and sugar combos?!). This is clearly rubbish, and by no means should fruit be cut out of the diet. It is satiating, contains micronutrients, and is generally pretty low in calories.

However, fruit is generally higher in calories than vegetables, so it is perhaps wise to increase vegetable intake before increasing fruit intake, if health is your goal.

Although it is possible to include refined sugars in the diet and still maintain a healthy body weight, the problem with doing so is that you miss out on the vital phytonutrients (micronutrients found in plants) contained in whole food carbohydrate sources. In addition, eating refined sugars as a regular part of the diet may create bad eating habits, and in situations where exercise decreases (with age, or lifestyle factors), the person may no longer be able to maintain a healthy body weight, leading to the well known health issues associated with being overweight or obese.

Whole grain consumption has been linked to longer life expectancy, and has been shown to reduce cardiovascular disease risk factors in obese individuals by reducing post prandial blood glucose response and reducing insulin resistance. [Malin et al, 2018; Kirwin et al l, 2016], so there is inherent benefit of including whole foods containing the micronutrients we mentioned earlier.

However, this does not mean that you have to plough in to every breakfast cereal that markets itself as containing 'whole grains'. This is hugely misleading, since most of these cereals are filled with highly processed additives, refined sugar, and lots of calories, for very little nutritional reward. Aside from the fact that very little whole grain is needed for companies to use this tag (ever eaten a Nutri Grain and a single oat falls out?!), eating processed cereal for breakfast means you are eating lots of carbohydrates (mainly refined sugar), lots of calories, very little protein (unless you use a full pint of milk in one serving - unlikely!) and very few micronutrients - generally a bad choice, regardless of cereals’ 'whole grain' marketing hype.

Whole grains include rice, oats, quinoa, barley, rye, freekeh, buckwheat, bulgur etc, all of which are good sources of carbohydrate. As with anything, consumption of these should be within overall calorie requirements for optimal health.

Another health benefit of carbohydrates is their effect on sleep. Carbohydrates release insulin into the blood stream, which pushes amino acids into cells. Because carbs are relatively high in tryptophan, carbohydrate consumption increasues the relative amount of tryptophan compared with other amino acids. This impacts seratonin, which benefits our sleep.


As we mentioned before, carbohydrates are the body's preferred fuel source. This is because we can store carbohydrates in the liver, brain and muscles, where we can break them down into glucose, which we then use as energy to feed our cells. Muscles in particular can store carbohydrates as muscle glycogen (up to around 15g per kg of bodyweight), ready to be used for some sort of physical exercise.

Most people need some carbohydrates in their diet to perform physical activity at their best, and this has been long-established in the scientific literature (for example in Loughborough University study on 30km runners [Williams, C., J Brewer and M Walker (1992) 'The effect of a high carbohydrate diet on running performance during a 30 km treadmill time trial' European Journal of Applied Physiology and Occupational Physiology, 65(1), 18-24]).

Nutrition strategies for performance are highly individual, and depend on the type, intensity and duration of the exercise being performed, as well as any concurrent body composition goals for the athlete in question, so this blog will not explore specific amounts of carbohydrate for optimal performance (since this is better done on a one on one basis [Book a Consultation].

You will also need to assess whether 'optimal' performance is really what you are looking for - which ultimately comes down to asking yourself why are you exercising? Are you a professional or competetive athlete? Do you have a personal athletic goal, such as an event (marathon, triathlon, competition etc)? Are you just looking to achieve a healthier body composition and boost self-esteem? Are you looking to improve your overall health? All of these will dictate the extent to which your nutrition should be angled towards or away from optimal performance.

Remember, sustainable beats optimal when optimal is not sustainable.

A few considerations for carbohydrate intake as related to performance:

Some people run better on carbs, others on fats, some on a combination of the two.

  • Most people need some carbs to fuel exercise

  • Using carbohydrates for exercise means that less protein is broken down during exercise

  • A good nutrition strategy may therefore be to concentrate your carbohydrate intake around your exercise sessions, for example, some before, and some after.

  • However, the importance of replenishing muscle glycogen quickly post-exercise is overstated for most people. 24hrs is enough to replenish glycogen to normal levels, which most people will be able to do if they include carbohydrates as part of their daily diet.

  • If you are a Tour de France cyclist, or competing in long duration/high intensity sports on consecutive days, then glycogen replenishment will be more of a priority.

  • If you are training different body parts on different days, in a weightlifting/bodybuilding programme, you will get plenty more than 24hrs to replenish muscle glycogen in those particular muscles.

  • If fat loss is your primary goal, then remember that carbohydrate timing doesn't matter for your fat loss!

  • Carbohydrates are crucial for high-intensity exercise, such as Crossfit, football, rugby, NFL etc.

  • For endurance sports, carbohydrate availability is also crucial, but there are also strategies that may improve the body's ability to utilise the carbohydrates that are available:

  • If you are in training phase and want to increase your body's adaptation to exercise, there is some benefit in doing some sessions with low carb availability (eg. fasted in the morning). This is known as the 'train low' strategy. This increases the body's ability to utilise carbohydrates once they do become available

  • A good analogy is with altitude training, whereby athletes train at altitude where there is low oxygen availability, so that they may more effectively use oxygen when it is more available

  • During a training phase, there may also be adaptive benefits to a 'sleep low' strategy, whereby, after an evening training session, only protein (no carbohydrate) is consumed. This appears to produce an adaptive benefit, and to increase mitochondrial density in muscle cells, enabling more energy to be produced.

  • Recommendations for carbohydrate intake to maximise glycogen storage are between 7-10 g/kg per day - which is alot in practicality.

  • For competition (such as a football/rugby/hockey etc match day, or a race, carbohydrate 'loading' (starting anywhere from 3 days to 24 hours before the competition itself) is an effective strategy to increase carbohydrate availability for the competition period.

  • Although there are some adaptive benefits to low-carbohydrate availability training, having a low-carbohydrate diet in the long term will be detrimental to performance.

Carbohydrate Myth-Busting

We've already busted the myth that carbohydrates make you fat (see above), but here are some other areas in which the popular narrative has deviated from the facts.

Low GI vs High GI - 'Simple' and 'Complex' carbohydrates

Created in 1980, the glycemic index is a measure of the ability of a carbohydrate to raise blood glucose. The standard against which all foods are measured is pure glucose.

The Glycemic Index (GI) of a food is measured by feeding a fixed portion of carbohydrates, usually 50g, and measuring the blood glucose response over a 2 hour period. Note that the feeding is 50g of carbohydrate, as opposed to 50g of the food in question (therefore for oats, which have 60g carbohydrate per 100g of oats, the required dose is 85g of oats in order to get the 50g of carbohydrate).

'Low GI' is classified as a GI score under 55. 'Medium GI' is between 55-70, 'High GI' is anything over 70.

The GI score of a food should not be used to dictate whether one food is healthier than another, and the classification of low and high GI foods often only serves to confuse people.

Here's why:

The GI score doesn't take into account portion sizing.

A number of factors can affect the GI of a food, such as the protein, fat and fibre content of that food, the type of starch (amylase or amylopectin), and the degree to which the food has been cooked.

The GI response is also altered when consuming a mixed meal (i.e. not just carbohydrates), so there is little applicability for real world situations.

A popular classification is 'simple' or 'complex' carbohydrates. In their truest sense, 'complex' carbohydrates are oligosacchirides and polysacchirides as we defined them above. The association is that these complex carbohydrates have a low GI and are therefore 'healthier' in some way. However, many foods that people think of as 'complex carbohydrates', such as sweet potatoes, wholegrain bread and rice, as well as vegetables such as parsnips and carrots, have a fairly high GI. The GI score is in no way indicative of the caloric content, or micronutrient content, of a food.

For fat loss, the GI score of a food is not indicative of appetite suppression, and if anything, contrary to popular belief, higher glucose (and therefore insulin) response to food is more likely associated with decreased hunger and energy intake.

A food's rank on the GI scale should be of no interest to someone for whom fat loss is the goal (unless they are a type 2 diabetic - see below). As we've said before, caloric value of the diet is the most important factor when it comes to fat loss. Effects of foods on blood glucose are transient, and have very little impact for fat loss.

For Type 2 diabetics, the practical application of the GI is in minimising the output of insulin and therefore maximising insulin sensitivity.

Spikes in blood glucose are closely followed by elevated levels of insulin which signals for the body to store the glucose in the liver and muscle. However, if the rise in glucose and insulin is sharp, it will fall again quickly, which can lead to hypoglycemia. Hypoglycemia is essentially low blood glucose levels (defined as below 3.9 mmol/L) and is characterised by feeling hungry, faint, jittery, irritable etc. Type 2 diabetics are advised to seek guidance from a trained clinical nutritionist.

For the vast majority of people, insulin spikes are not a problem (despite what the ketogenic crowd would say), and the GI scale should not be of interest. Insulin is not the enemy!

[For more on the falsification of the 'insulin hypothesis' perpetrated by Gary Taubes and fellow ketogenic diet evangelists, look for James Krieger's material on his Weightology blog].

Carbohydrate Tolerance

You may have heard that people are more 'tolerant' to carbohydrates than others, and that certain people are 'intolerant' to carbohydrates.

This is a classic example of a half truth.

While it is true that some people digest and absorb certain foods better than others, carbohydrate intolerance is not a thing. A good example is celiac, which is a long-established medical condition that means that people must avoid gluten (which is a protein found in wheat, barley and rye). For people diagnosed with celiac (and also with non-celiac gluten intolerance, which is a less extreme version of the condition), this will likely involve avoiding bread, pasta, cereals etc - foods that also happen to have a high carbohydrate content. The person is intolerant to gluten, NOT to the carbohydrate, and certainly not to all carbohydrates.

While your body may struggle to digest certain foods, in most cases, the devil is in the dose, meaning that high amounts of these foods may lead to some gastrointestinal discomfort. [For more on gastrointestinal health, there is a gut health article coming soon].

This leads on to intolerance tests, such as IgG tests or the newer mediator release test, whereby a person is tested (usually via blood sample) for their 'tolerance' to various foods. What will then happen is that they will be given a (usually long!) list of foods that they are intolerant to in varying degrees.

These are, unfortunately, a complete waste of time and money. That's not to say that food intolerances don't exist, they do - but there is currently no test that works to test for them.

Many people will cut out some or all of the foods on the list, and lose weight and/or feel less bloated. But this is not due to the test in any way. By chance, they may have cut out a food that they were intolerant to, and most likely they ended up eating fewer calories overall, partly due to the sheer amount of foods that they cut out, and partly to the fact that they may have cut out some higher calorie foods, and replaced them with lower calorie foods.

Take Home Points

  • Carbohydrates are molecules of varying complexity, which are all broken down to the simplest form (monosacchirides) before they are absorbed

  • Carbohydrates are used for energy by muscles, brain, kidneys and liver

  • Calories are the most important consideration for fat loss. Carbohydrate content of a diet (including the source of those carbohydrates) doesn't matter for fat loss, as long as the person is in a calorie deficit. This has been proven over and over again.

  • For health, the best sources of carbohydrates are whole foods: potatoes, sweet potatoes, root veg, rice, whole grains, fruits and vegetables. Remember that a huge marker of health is weight maintainence, so calories must also be factored in.

  • For performance, most people need carbohydrates in order to fuel exercise. The amount will depend on the intensity, duration and frequency of the exercise in question

  • There are a number of interesting strategies when it comes to carbohydrates and the optimisation of performance (scroll up for more)

  • The GI of a particular food is not important (unless you are a type 2 diabetic or a performance athlete)

  • Carbohydrate intolerance is not a thing. Celiac is a thing. Non-celiac gluten intolerance is probably a thing. Food intolerances are a thing, but there are currently no reliable tests for them.

  • Carbohydrates are not the devil

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