Although many of us have become a little ‘carb-phobic’ these days it’s important to remember that in healthy quantities carbohydrates (including glucose and fructose) can be processed effectively by our body, either used for energy or stored in our muscles and liver as glycogen. For this reason one of the best times to consume carbohydrates is following exercise, when our need to replenish glycogen stores is greater.
There is some debate as to whether this applies to the precious 1 hour post exercise window or if the impact could be felt over a longer time period. More recent studies have shown our insulin sensitivity is actually higher for up to 48 hours – not just 60 minutes. Either way, having some carbohydrates following exercise is, in our opinion, good shout.
Natural Vs Processed Sugar
Lots of modern day foods now contain synthetic forms of fructose or glucose and ideally you want to avoid these. Soft drinks and confectionary in particular are often loaded with them so it’s important to always check the labels of what you’re about to consume. Large amounts of fructose, in particular, can exert a very harmful effect on the body. Fructose is metabolised by our liver which is only equipped to process and store small amounts. If we flood it with fructose we can increase our risk of fatty liver disease and cancer, especially if fructose is combined with too many polyunsaturated fatty acids (see our Guide to Fats). This is yet another good reason to avoid takeaway/fast food as it is often based on a lethal combination of deep fried food (polyunsaturated fats) served with an excessively large fizzy drink. The message here is always refuel with natural sources of carbohydrates instead.
Glucose Post Exercise
So if our muscles use and store glucose it makes sense that we top up after exercise. It’s not completely essential as our bodies are capable of manufacturing glucose via a process known as gluconeogenesis derived from the following Greek words:
- glyks = sweet
- neo = new
- genesis = origin or generation
This literally translates as a new generation of sweet or sugar is born. The body can make glucose from protein but the fact that it does this has led many people to argue the importance of glucose consumption in the first place rather than forcing the body to gain its supply from protein. It’s estimated we use around 30-60g carbohydrates an hour during glycogen depleting exercise so consuming these in addition to your usual requirements is wise. Though obviously this depends on the level of exertion, your body composition and other factors so this is just a guide. In terms of sources of glucose we always recommend single ingredient foods where possible to minimise any added nasties that may disrupt digestion. Potatoes, rice, sweet potatoes, quinoa, buckwheat, root vegetables and fruit (see more below) are all nutritious sources of glucose.
Fructose Post Exercise
Despite the bad reputation fructose has, a little fructose in your diet from fruit or natural, unrefined sweeteners including raw honey or maple syrup can actually be helpful in replenishing liver glycogen. Studies have shown that when consumed post exercise fructose also aids the transportation of glucose into the muscles.
Many studies performed on athletic populations have suggested an optimal split for sugar consumption post exercise would be 70% from glucose and 30% from fructose. Thus adding a few pieces of fruit into your daily meals, especially post exercise, could actually help your body to recover from training and avoid the excessive release of stress hormones like cortisol and adrenalin that occurs if your blood sugar drops too low. So as long as your primary source of carbohydrates are sourced from glucose adding in a little fructose will ensure both your liver and muscles are replenished with glycogen.
Glucose Fructose Ratios in Fruits & Sweeteners
Choosing fruits that offer more or equal amounts of glucose than fructose (remember the 70:30 split) is a good option here. The other nutrient that fruit offers is potassium. We love Paul Jaminet’s recommendations of choosing fruits that offer preferential ratios of glucose, fructose and potassium. His book Perfect Health Diet lists fruits in a hierarchy with cantaloupe melon, raspberries, papaya and bananas at the top.
In terms of added natural sweeteners you might use like cane sugar, honey or maple syrup it’s worthwhile applying similar principles and thus familiarising yourself with the ratio of fructose and glucose in these. As you can see from the following (taken from the awesome Natural Food Finder) sugar, honey and maple syrup are around 50% glucose and 50% fructose. Agave Nectar/Syrup is much higher around 70-90% fructose. For fat loss goals we always advise keeping added sweeteners to a minimum (or using Xylitol or Sweetleaf Stevia alternatives) and if you suffer from cravings and addictive behaviour towards sweet foods limiting them is wise.
Post Workout Fitter Flapjack
We used to love munching on flapjacks and so decided to put all this useful information into a post workout Fitter Food Flapjack recipe. One of the priorities of your post workout nutrition is to lower the inflammation caused by exercise. For this reason we tend to avoid the allergenic grains like wheat, barley or rye. In our flapjacks we used buckwheat flakes as it comes from the rhubarb family and so tends to be a little friendlier on our immune system, you could also use Amaranth or quinoa flakes which are widely available online and in health food shops. Most people also seem to tolerate rice well and so you could opt for rice flakes. The best sweeteners to use would be raw honey or maple syrup given the more favourable glucose:fructose ratios. We added cinnamon to the recipe because it helps improve insulin sensitivity and also has a potent anti-inflammatory effect. We used a protein powder to help top up protein stores post workout and some coconut oil and desiccated coconut to add in healthy saturated fats. We included Himalayan salt to help replenish electrolytes and improve post workout hydration. We chose hazelnut butter, chia and pumpkin seeds due to the their favourable omega 3:6 ratios, these are much lower in omega 6 than some other nuts and seeds and omega 6 fatty acids may elevate inflammation. Overall we were pretty chuffed with the results! Check out the recipe here.