Updated: Jan 19, 2019
So we’ve heard a lot about carbs in the press lately and I thought I’d offer my scientifically balanced view on the subject rather than the opinion based nutritional science that is usually spouted online or in magazines.
The basic function of carbs in our body is to provide energy. I think we trap on about energy quite a bit but it is worth thinking about energy in our bodies in a more abstract way to help to understand it.
Just like all our electronic goods need energy in the form of electricity, our bodies need energy to function. Some electrical items like hairdryers, need a lot of electricity to function for short periods and some, like fridges need a small amount of constant energy.
Our bodies are the same. Our lungs, liver and other organs need a little bit of constant energy and when we exercise, our muscles, heart and lungs need a lot of energy for a short period while we exercise.
The energy that our body uses is glucose, which we get from carbohydrates in our food.
Carbs come in many different forms, from the complex starches like bread and potatoes, to the moderately complex like milk sugar, to the simplest forms like table sugar and syrup.
When we eat any form of carbohydrate our body gets to work to break it down to glucose. So remember, when you are eating a bowl of pasta, your body will turn it into sugar (biology is magic!).
As discussed, we need constant energy just for our lungs and our brains to function, and for that reason, you use significantly more energy during a 6-hour sleep than you do during a 1-hour workout. So in order for our bodies to continue to work at all times we have three ways of making sure glucose is always available.
The easiest way for our bodies to have glucose is when it is still in our bloodstream after a meal. In electrical terms, this is a relatively small supply that is sitting in the wires (i don’t know if that is possible electronically…but you get the idea).
When we eat more carbohydrate than we need at a meal (which is almost always unless you are in the habit of exercising heavily after every meal) and we have more glucose than we immediately need, we store it in our muscles and livers so that it is available later. This is a bit like a battery. Stored energy that will eventually run out.
As a last resort, if all of the glucose in the blood stream is used up and the stored energy in the batteries in your liver and muscles is used up, we turn to our biggest source of energy - body fat.
The problem with body fat is that it is a bit like trying to use mains electricity in a developing country in the 1950s. It delivers energy quite slowly and when you’re relying on it, you feel a bit sluggish and underpowered. That said, most of us have plenty of it and want to use it up so we have to force our bodies to do so.
Now let's look at the pros and cons of carbohydrates in weight loss:
If you have kept up with the biology and the weird electricity analogy above, you are probably thinking that it is bloody obvious. If we don’t eat carbs then we have no glucose in our blood or in the batteries in our livers and muscles and so we are forced to burn fat and so we lose weight. Problem solved, no need to read on. I should stop writing now, we have cracked it…but as always my friends it isn’t that simple.
Having a totally carbohydrate free diet makes you feel AWFUL and smell weird. It makes you sluggish and constipated and have brain fog. You will probably have no energy to exercise and your diet will proportionately higher in fat than is thought to be safe. Even if you were able to sustain this perma-hangover like state for long enough to lose your excess body fat, we don’t know the long term consequences of eating a very low carbohydrate diet for long periods so we can’t tell you if it is safe or not.
When we look at alllllllll of the scientific research on healthy eating and reducing our risk of disease, we find that actually, the healthiest people with the lowest risk of disease eat a relatively high carbohydrate diet.
A lot of these findings come from the Mediterranean Diet studies which were carried out in the 1990’s and were examining a population with relatively little ‘Western’ influence on their food choice in terms of processed and fast food and in a population who would have still been very physically active.
If you go to these countries now, you will see that obesity rates are rising rapidly, alongside their risk of heart disease and cancer, even though the core components of their diet remain the same.
Why? Because they use supermarkets instead of growing or producing their own food, physical activity levels have dropped, people drive everywhere and there is little manual labour anymore. In my mind, this leaves a question over the applicability of these studies to our modern lifestyle.
BUT there is a lot of other compelling evidence that carbs are not the enemy. For example, we know that most people in studies find a higher carbohydrate diet easier to stick to in the long term. They tend to report feeling better and we know that they are likely to be benefiting from the fibre and vitamins provided by the carbohydrates that they are eating.
People argue that protein (meat, fish, cheese, eggs) and fat makes you feel fuller than carbohydrates but in reality, the studies tell us that wholegrain carbohydrates are just as satisfying.
So this is the problem. The physiology tells us one thing and the nutritional and behavioural research tells us another. So how do you balance these two and come up with a sensible solution?
The truth is, that there isn’t a ‘one size fits all’ solution. You need to think about what you do on a day to day basis and what you need fuel for. You also need to think about your preferences and what you feel you can stick to in the long term.
What I would say with the greatest degree of certainty that I can is that a carbohydrate free diet isn’t a good solution for anyone long term. If you think that a low carbohydrate eating pattern might work for you then give it a try but keep having fruit and any vegetables you like (except white potatoes) and small amounts of pulses for fibre. Try avoiding bread, pasta, rice, flour, cereals and white potatoes and enjoy more nuts and root vegetables as a replacement.
If you are a carb lover or are a very active person you will probably feel awful on a low carb diet so focus on keeping the fat low and stick to wholegrain carbohydrates. Consider ‘processed food’ to include white bread and pasta and avoid it when you can. Remember that when you eat carbs, the fat that you eat will be stored for later so have lean meat or fish, as your protein source and choose low fat dairy, avoid fried food and stick to poaching, steaming or baking.
I personally choose a lower carbohydrate diet. I have nuts and yogurt for breakfast, salad for lunch and meat or fish with 3 or 4 different vegetables for dinner. I will snack on fruit and more nuts if I’m hungry. This works for me because I love all vegetables and salad foods and it is therefore sustainable for me to maintain my energy and keep lean.
I exercise in the morning because I know that I will be burning fat as my batteries will be empty from fasting overnight while I sleep. This makes my cardio REALLY hard but I am blessed with a love of exercise and ridiculous determination.
Obviously I sometimes eat carbs, I had two blueberry muffins, some crips and a pizza this week and I have just eaten a bowl of sugary cereal while writing this blog(!). Consider that if you are lower carb or low fat 80% of the time you can afford to relax your rules 20% of the time.