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Are carbohydrates bad for you is a topic I’ve wanted to blog on for some time. Many have an opinion on the matter but few appreciate the true facts. Therefore, I finally wanted to put this debate to bed and offer a balanced and hopefully informative take on this.

What are carbohydrates?

Carbohydrates are made up of carbon and hydrogen, hence the then – ‘carbo – hydrates’.

Carbohydrates are one of four macronutrients in our diet. Macro means big. So carbohydrates are one of our big nutrients. In other words, they are one of our energy providing nutrients. They help to fuel all the activities our bodies do day to day whether that’s your heart beating or running a marathon.

They provide 4kcal per gram. This is the same as protein, which also provides 4kcal per gram. Alcohol provides 7kcal per gram whereas fat provides 9kcal per gram. So on the whole, carbohydrates are one of our lowest calorie food options.

Types of carbohydrates

Carbohydrates are found in lots of food groups across our diet. Starchy carbohydrates, such as bread, pasta, rice, cereal, oats, cous cous, quinoa, potatoes etc are all forms of carbohydrates. In fact, this is probably the most obvious place in our diet we get carbohydrates.

Sugar is also a carbohydrate. Therefore, all processed sugar such as that found in cakes, biscuits, desserts, chocolate etc is carbohydrate. The same applies to natural sugar found in fruit and the lactose found in milk and yogurt.

There is also some starch in legumes, such as beans, pulses, lentils, chickpeas and a very small amount found in vegetables.

Problems with comparing carbohydrates

Hopefully you’ve noticed carbohydrates are found in lots of different places in our diet. There are also lots of different options. For example, you can eat brown rice or white rice, white bread or seeded bread, fruit or cake and even broccoli or chips. So although all these foods come under the carbohydrate banner, they are really different in terms of their effect on your body.

And this really gets to the crux of the debate of whether carbohydrates are bad for you.

Hopefully we can all agree broccoli is good for you whereas a biscuit is less so.

When studies or people debate about carbohydrates, they rarely separate out what type of carbohydrate they are referring to.

Studies are particularly bad at this. Often the type of carbohydrates eaten by the participants is not specified. This is more prevalent when studies use an observational methodology and observe groups of people eating their habitual diet rather than giving them a diet to follow. The reason for this is because it is really hard to get people to follow a diet for a long period of time. Therefore, it is easier to look at what people are already eating and then compare that against their health outcomes.

Study results

When all carbohydrates are grouped together, the results on our general health is a mixed bag. Some studies report beneficial effects whereas others show definitive negative health outcomes.

However, as we get more specific and start to specify the types of carbohydrates that were studied a new picture emerges.

When higher fibre, lower glycaemic index, more nutritious carbohydrates are studied, the impact on our health appears unequivocally beneficial. When people eat lots of vegetables, legumes, fruits and granary, wholegrain, brown types of starch, people have lower rates of type 2 diabetes, cardiovascular disease, obesity, sleep apnoea, cancer, better gut bacteria and the list goes on.

Conversely, when peoples carbohydrate intake is mostly made up of processed carbohydrates such as processed sugar and ‘white carbohydrates’ for lack of a better expression, those markers of health increase.

Other factors

There are also a number of other factors we need to keep in mind when assessing whether carbohydrates are bad for you.

Total carbohydrate intake

UK government recommendations suggest eating around 50% of your calories from carbohydrates. On a 2000kcal diet per day that is around 1000kcal or 250g of carbohydrates per day.

That seems like a lot but remember, that is your entire carbohydrate intake from all sources. Just eating your 5 a day from fruit and vegetables, depending on your choices, will provide an obligatory 100-150g of carbohydrates per day. This leaves less room for eating starch and in reality limits you to around 3 small handful portions of starch per day to make up the additional carbohydrates from starch.

The problem is, people see 250g of carbohydrates and automatically jump straight to starch. Comments like ‘that’s like 15 pieces of bread’ are common. However, I think they are missing the point of variety and that’s only 15 pieces of bread if you eat nothing else with carbs in it like vegetables or fruit, which isn’t a balanced diet at all.

Activity levels

Another big factor playing into this is how active you are. Think about it, 250g of carbohydrates per day is on the assumption you meet all the healthy living recommendations. This includes exercise.

The bear minimum physical activity everyone should be doing is 30 minutes per day, of a moderate intensity, 5 days a week. That isn’t a lot but only two thirds of people do this. Yet alone go above and beyond. Also, peoples exercise levels decline as they age and when are people most likely to suffer from ill health? When they get older. When are people most likely to start to gain weight leading to an exacerbation of ill health? As they get older. However, the rhetoric often focuses on only one cause of weight gain or ill health and sometimes this culprit is carbohydrates.

So we aren’t as active as we should be or as active as we used to be.

If you are inactive or do not regularly raise your heart rate, you need to eat less. This is true for your total calories and for your total carbohydrates.

Athletes, who are the pinnacle of health, eat carbohydrates to fuel their activity. If carbohydrates were bad for you across the board, they wouldn’t be a staple of the fittest among us. The difference is they burn up the calories. Therefore, they get the benefit of all those healthy carbohydrates without the problem of gaining weight or eating too many carbohydrates.

Body weight

Keep in mind also, in the UK we overeat in general. As shown by our obesity levels. This is true of overall calories and of carbohydrates themselves. So we also eat too many carbohydrates typically. If you are overweight or obese, your risk of developing health conditions increases. What many people fail to understand is it isn’t the carbohydrates doing this specifically.

Yes, carbohydrates have energy and if you overeat on them, you will gain weight. However, the same is true of fat and protein.

You need to look at the diet holistically. What else are you eating, are you drinking alcohol, what portions are you eating etc? Also, even if you eat healthy, if you’re overweight, you’re eating too many calories for your body and/or activity levels. Therefore, even though it’s healthy food, it’s too much of a good thing and thus it becomes unhealthy.

So to simply blame the carbohydrates is a bit unfair, in my opinion.

So remember, your diet needs to reflect how you live your life.

Lets take stock before moving on

Ok, so to answer our questions thus far, we need to define the type of carbohydrate, how much you eating and how this fits with your other lifestyle choices like exercise.

If you are overweight but eat all mostly healthy foods in your diet, this still shows us there is a positive energy balance. Meaning, even if it’s healthy, you’re having too much of a good thing, not exercising enough and if you’re overweight, this is bad for your health. However, the tendency is to blame the carbohydrates, when in reality, this is not the case.

Type 2 Diabetes

Here the water muddies slightly. A type 2 diabetes diagnosis adds another dimension to the debate.

All carbohydrates are converted into glucose and glucose is what increases blood glucose levels. Therefore, carbohydrate must be bad for you, right?

Well, lets take a step back and ask, why are your blood glucose levels high in the first place?

Type 2 diabetes causes

Type 2 diabetes is caused mostly by lifestyle factors. Basically, 90% of people with it, are overweight or obese. There will be those who develop it into old age but this tends to be conservatively managed. The younger you develop type 2 diabetes the more likely it is you did so due to weight or fitness related issues.

Type 2 diabetes is caused by insulin resistance and fat around your organs. Previously your body could use glucose as it intends to but with insulin resistance developing, it can no longer get enough glucose out of the blood and into the cells. This is because the cells are clogged up with fat and so insulin cannot open up the cells for glucose to go in. The result is high blood glucose levels.

If you didn’t have diabetes, you can eat as much carbohydrates as you like and you will not get a high glucose level. Therefore, the problem doesn’t lie with the carbohydrates but instead your bodies inability to process them.

Granted, low carbohydrate diets are regularly used in the management of type 2 diabetes. In fact, I use this strategy with patients myself. Even Diabetes UK’s guidelines suggest aiming for no more than 150g of carbohydrates per day if you have diabetes.

Still not carbohydrates fault

The reason for the use of lower carbohydrate diets is because often patients do not change their lifestyle sufficiently to address the underlying problem with their glucose control. Whether this is an active choice or whether it’s due to circumstances such as poor mobility, low carbohydrate diets have their place in such situations.

Often, patients who follow low carbohydrate diets, actually just start eating the amount of carbohydrates they should be eating for their activity levels anyway. So it just helps them regulate their dietary intake, which is a good thing.

So on one hand, yes low carbohydrate diets can be used to help manage type 2 diabetes. On the other hand, no, it doesn’t make carbohydrates bad for you.

Had they not developed type 2 diabetes there would be no problem with their glucose levels. Eating lots of vegetables, fruits, legumes and wholegrains and being regularly physical active lower the risk of developing type 2 diabetes. Therefore, prevention is always the best cure and by eating the right types of carbohydrates, you actually lower your disease risk.


Hopefully that has cleared up some confusion around carbohydrates in our diet. There are types of carbohydrate that are consistently shown to improve markers of health and lower rates of disease. Vegetables, fruit, legumes and slow releasing wholegrain and granary starchy carbohydrates demonstrate a beneficial effect on our health.

On the flip side, the more processed types, namely sugar and processed starch, consistently achieve negative health outcomes. So it really is a tale of two cities.

Therefore, the goal is to aim to eat the right amount of the right types of carbohydrates to help achieve your lifestyle or diabetes management goals.

Need more help

If you need more support we offer a range of 1:1 consultancy services and online programmes focused on helping you improve your glucose control and health for the long term. These include our type 2 diabetes recovery programme, type 1 glucose stability programme and winning weight loss programme. Go to the pages using the links above or in the headers or get in touch if you have questions.