Gosh what a topic Carbohydrates is! So many theories on high carb vs low carb diets. Having spent a long few days listening to some awesome podcasts and scouring the web for articles I am going to try and deliver you the facts! Bare with me, sit back get comfy - this is going to be a long one!
What are Carbohydrates?
Carbs are essentially compounds of carbon, hydrogen and oxygen. They come in different sizes:
Monosaccharides - a single carb e.g glucose, fructose and galactose
Disaccharides - Two carbs stuck together e.g. Lactose, Sucrose, Maltose
Oligosaccharides - more then two but less than ten carb molecules e.g. Maltodextrin, Raffinose
Polysaccharides - Many carb molecules stuck together! e.g. Starch, Glycogen and Cellulose
So already things are getting complicated!
A simpler way of thinking of carbs is as:
Sugars - small, sweet carb molecules found in foods
Starches - Long chains of carb molecules which our digestive system breaks down into simple sugars
Fibre - A form of carbs we can't digest but that the bacteria in our large bowel can make use of!
Why do we need Carbs?
The main purpose of our dietary carbs is to provide energy. Nearly all carbohydrates get broken down into glucose which is the form in which we use them for energy. Carbs can also be stored as glycogen in our muscles and turned to fat and stored for later use. Most important our brains thrive off glucose!
Fibre is one exception as we can't digest it ourselves. However our guts bacteria loves the stuff! they can actually break some of it down into fatty acids that some of our calls can use for energy.
Where do we store excess carbs?
We have two major carb stores.
Our muscles - Our muscles store energy in the form of glycogen. This energy store can only be used by the muscle in which it is stored in.
Our Liver - Again glucose is stored here in the form of glycogen. The liver can hold between 80-100g glycogen only . That equates to approximately the size of half an apple.
Excess carbs can also be stored as fat, which if necessary can be converted to energy - hence we can 'burn' fat.
We also maintain a certain level of glucose in our blood but it is a relatively low level. The brain and nervous system are directly dependent on blood glucose as fuel. It is important that it is closely regulated for our brains health.
How do we regulate our blood sugar levels?
Without diving into a whole new blog on diabetes we can briefly analyse that blood sugar levels are controlled by insulin. When sugar enters the blood Insulin is released to allow glucose to enter cells for energy and help it be convert it to glycogen to be stored.
If our blood sugar levels rise too high it can be dangerous for our bodies. Those individuals with Type 1 diabetes produce little or no insulin themselves so inject it to control their blood sugar levels. Not eh other side of the coin, too little blood sugar can also lead to problems so those individuals who inject insulin often have a sugary snack or treat on them incase they cause their blood sugar levels o go too low. As you can tell its a fine balancing act!
How much carbohydrate do we need a day?
Now the figures for this seem to vary from country to country. the NHS suggest that we have 260g of carbohydrates a day - approximately 50% of our daily calorie intake. The brain uses approximately 180g of carbohydrates a day alone! The rest of the carbs injected are sent to the muscles, replenish the liver, burnt off during exercise or stored as fat. Now the plate below is 3/4 fruit, veg and 'good carbs'. remember they also have other macronutrients so we aren't eating 75% carbs as it may appear.
So carbs can make you fat?
Excess of any food type can make you gain weight! However what we ned to be careful of when eating carbohydrates is the 'added sugars'. Now sugar isn't something that we should be afraid of. it has been around for centuries - in fact in the victorian times we possibly consumed more table sugar than we do now with some people having up 7 spoons in their tea! the problem nowadays is that we eat far too much processed food with hidden or 'added' sugars in it.
These added sugars come in the form of sucrose, honey and syrups that are often aded to foods that we would never think about. Tomato ketchup for instance. Now if you are having a squirt of Tommy K once a month as a treat this isn't necessarily a bad thing, but if you have it with every meal you are exposing yourself to far more sugar intake than you realise. Its hidden in loads of other processed foods too and other store cupboard ingredients like stock cubes that you would never guess had added sugar in.
To avoid these 'added' sugars we need to understand packaging. If we look on the back of a food packet it will tell us the number of carbohydrates and usually we also have a category which says ' which sugars'. Now the frustrating thing here is that this includes all sugars not just the added table sugar kind. We need some of these simple sugars in our diet. the ones that come for fruit and veg for example. So only eating those foods with 5g or less carbohydrates 'which sugar' dramatically cuts down our carb intake. This can prevent us from eating the fruit and veg that we need which contain so many more important nutrients as well as the carbohydrates.
So I would suggest ignoring that part (to a certain extent!) and having a look at the ingredients list. If sugar is listed in the top three ingredients you can almost guarantee that it has extra 'added' sugar which we don't need.
Should we all be on a low Carb diet?
Low carb diets are extremely fashionable at the moment and one thing that is important to remember is that everyone is different. Diets such as the Keto diet work really well for some people but not for others. My honest advice is to aim towards eating a balanced plate. It is the one way to make sure we are getting all the nutrient our body needs for optimum health. The way diets like the Keto diet work is by reducing our carb intake so that we start to use ketone for energy. These ketones are derived from our fat stores.
One of the reasons that low carb diets are so popular is that when we start them we tend to see a pretty dramatic weightless. This is because when we eat carbs we take on a hold water. Cutting them out of our diet releases that water and therefore weight. However reducing carbs quickly can also lead to 'carb flu'. We feel sluggish and tired as our body doesn't have its favourite every source. Some people actually feel like they have the flu! Now there are those individuals that come out of the other side of the 'carb flu' and feel great. They have started using ketones for energy formed from their fat supplies.
Lots of people do thrive on low carb diets such as this and it can be useful for those managing type II diabetes. But personally I would still question whether they are able to get all of their nutrients and how well their digestion is functioning given that the microbiome in our bowel thrives on fibre. Also if they worked for everyone, everyone on a low carb diet would lose weight and that just isn't the case. Remember to talk to your GP or a registered dietician before embarking on any diet change.
So what are healthy sources of Carbohydrate?
Healthy sources of carbs are those with naturally occurring sugars in - fruit and vegetables - and those that are high in fibre and starch than those food sources that are high in 'added' sugars.
Fruit, vegetables, pulses and starchy foods, such as the potato, provide much greater nutritional variety than sweets, chocolates, pastries and cake.
We need to start avoiding labels and to look deeper into the make up of our foods. We tend to label things like pasta, bread, rice as 'carbs' but in reality they are so much more than that! A piece of whitbread for example is only about 47% carbohydrate. it is also 10 % protein, 4 % fat and the rest is water. The humble forbidden white potato is actually only about 10-20% carbohydrate and is actually an important source of fibre - especially with the skin left on!
Also if we use wholemeal options in our diet we are not only adding more protein to our diet but also lowering the glycemic index of the foods we are eating preventing spikes in blood sugar levels.
(Those of us with irritable bowel symptoms may need to be careful with which carbs we choose. Again I would advise seeking the advice of a dietician to help with these issues.)
What is the Glycemic Index?
The Glycemic Index (GI) is the speed at which a food raises the blood sugar levels. This may sound like a genius way to reduce sugar intake in our diets and to eat healthier. In some ways it is and it can be very useful for those who have an insulin intolerance however it isn't fool proof. For example, Water melon and parsnips have a higher GI than chocolate cake! This is because the chocolate cake also contains fat and proteins which slow the digestion of the carbohydrates and slow the spike in bold sugars. The watermelon and parsnips don't have as many of these other macronutrients in to slow the flow of sugar into our blood. However eating loads of chocolate cake is definitely worse for us than eating watermelon and parsnips!
However if we look at different types of one food source it can be quite helpful. Lets take bread as an example. White bread has a high GI as it has little in it to disturb the metabolism of sugar. Wholemeal bread has a lower GI than white bread as it contain more protein and fibre. Finally wholemeal, wholegrain bread has lower GI still as it has lots more protein, healthy fats, soluble and non- soluble fibre as well as lots of vitamins and minerals which slow down the digestion process.
The Glycemic Load rating is possibly more helpful as it not only factors in the rate in which our blood sugars spike but also for how long they stay high for. As said above it can be useful for those with diabetes but as a general diet it can be very misleading without the right education.
What about sweeteners?
Now these little carbs are interesting! They are what we call polyols or 'sugar alcohols'. this is because their chemical make up resembles part sugar, part alcohol. Don't worry they don't actually contain any ethanol so they aren't actually alcoholic. They are extremely sweet! Examples include aspartame, saccharine and sucralose.
Take the average Cola drink. A non diet option may have up to 9 teaspoons of sugar in. A diet option may only have a tear drop of aspartame in. That is how sweet these sugar alcohols are! Now the ones listed above come under non-nutritive artificial sweeteners but technically, per gram they have the same amount of kilojoules as a gram of table sugar but because they are so much sweeter, a lot less is needed so the overall energy of the diet drink will be much less.
Now artificial sweeteners aren't that good for us. They have been linked to cancer in rats but also they can play havoc with our guts! Lots of diet products have warnings on saying that over consumption can lead to tummy upset - the term 'anal leakage' has actually been used! This is because these types of carbs attract water through osmosis. If we consume a lot of them lots of water gets bound to them in our gut which can lead to diarrhoea. They are so good at this that some laxatives contain these polyols. Also these polyols can actually be metabolised by the bacteria in our bowel. The bi-product of this is wind! As with everything individual difference must be taken into account as these carbs affect everyone differently.
The take home message!
We need carbs for optimum brain health, nervous system health and energy
Too many of the wrong carbs can be detrimental to our health
Avoid added sugars but don't be afraid of the natural sugars in fruit and vegetables and grains
Wholemeal and wholegrain carbs are good for you as they contain proteins and fats which slow down sugar metabolism and keep you feeling fuller for longer
We need to consume up to 260g of carbs a day (based on an average built female with a relatively active lifestyle)
Try to avoid artificial sweeteners - for the sake of your friends!
Now I have stayed away from talking about fibre in too much detail in this blog as I feel that it needs one on its own - plus you could probably do with getting up and moving after staring at your screen for the last 15 minutes! So keep an eye on my website for further blogs on fibre!