Could Carb Cycling Be The Key To Getting Fitter, Faster?
We all know that fuelling properly can be the difference between a good and a great workout. And that carbohydrates can be essential for both maximising workouts and recovering effectively. But what about carb cycling? If you've never heard of it, carb cycling is a method of eating based around adapting your carb intake according to your training.
Still not sure what we're talking about? Here we take a look at what carb cycling is, if it’s good for you or not, and what to eat if you are carb cycling.
What is carb cycling?
‘Carb cycling is where someone alternates their carbohydrate intake on different days, with the aim of weight loss or fitness and performance goals,’ explains London-based dietitian Reema Pillai.
‘It involves eating high carbohydrate foods, usually on the days where a person is exercising more intensely, followed by lower carbohydrate days, usually on rest days. The theory is that the change in carbohydrate intake can support muscle building and recovery, as well as fat metabolism and energy levels. By having days of low carb intake, the body switches to fat as its main source of fuel, therefore burning more body fat than normal.’
Dr Sam Impey, co-founder and chief scientific officer at personalised sports nutrition app, Hexis (previously head of nutrition at Great Britain Cycling Team) adds that carb cycling also known as carbohydrate periodisation in the world of sports nutrition – where you match the amount of carbohydrate that's in your diet before, during and after exercise in a way that matches the energetic demands of that training session.
A good example of this, he says, is if you’re going for a run in the evening after work, you might have some carbohydrates at lunch or as a snack in the afternoon, so that your muscle glycogen stores (which is the body's store of carbohydrates), is topped up enough so that you're able to complete the run.
‘The whole idea is that we don't want to over-fuel with carbs, because we know that potentially has negative effects from a training adaptation perspective. Instead, it’s about aligning your intake of carbohydrates to the duration and intensity of the training session.’
What are the benefits of carb cycling?
Improved energy stores
Supports muscle recovery and growth after exercise
Reduced levels of fatigue
Fat loss
Simply put, ‘you can get fitter faster from the same amount of training, and it helps to achieve your body composition goals by managing your total calorie intake,’ says Dr Impey.
How does carb cycling work?
Low-carb days
On rest days or days with no training, opt for lower carbohydrate foods and make sure you're filling up on plenty of protein, fibre, fruits and vegetables (since you won’t have a high demand for carbohydrates on the body).
Typical carb intake can be between 75-125g carbs per day
High-carb days
Then on days when you do have training, increase the carbohydrate amount in the meals before and after training sessions.
‘So if you're training in the early afternoon, for example, you might have a lower carbohydrate breakfast and then a medium or high carbohydrate lunch to fuel up ready for that training session,’ Dr Impey explains.
‘After training, you'd opt for a medium carbohydrate snack in the afternoon, and then potentially a low carbohydrate dinner.’
Typical carb intake can be between 150-200g per day
But, there are no set rules when it comes to carb cycling...
‘It's not about “today is low carb, tomorrow is high carb”. Instead, it’s about creating that periodisation on a meal-by-meal basis, so that we're optimising how our bodies adapt to training. And that's the most powerful way to use carbohydrate periodisations,’ says Dr Impey.
What role does timing play in carb cycling?
Timing is really important. As mentioned, you need to make sure you're having carbohydrates before you train, as well as afterwards, so you’re able to get the most out of your training session and then recover effectively.
Is carb cycling suited to one type of person or someone looking to achieve specific goals?
Dr Impey says carb cycling is pretty ubiquitously useful for everybody – and can be customised based on your goals (fat loss, muscle gain, athletic performance etc).
‘Perhaps the only example of where it might not be useful is for people doing kind of multi-day ultra-marathon run, where you may want to shift the metabolism to burning predominantly fat,’ he adds.
‘But for the general population – for anyone exercising and looking to get better numbers at parkrun, improve their body composition, or do better at Hyrox or CrossFit – carbohydrate periodisation is a really beneficial tool that you can add to your training toolbox to help improve physical capacity.’
Pillai adds that carb cycling is best suited for ‘athletes and people who regularly perform high intensity or endurance workouts, or who are regularly strength training’. Why? Because those who are trying to build muscle can benefit from the higher carb days for energy, and lower carb days for fat loss.
‘People who struggle with a complete lower carb diet approach may find this works better, as you do not have to completely cut them out for ever,’ she adds.
How does carb cycling affect metabolism?
According to a 2018 research paper, published in Sports Med – on which Dr Impey was a lead researcher – by starting your training sessions in an optimally fueled state, you’re able to get better adaptations from the same training.
So, properly fuelled training sessions = better performance, increase in metabolism or metabolic rate, and aided recovery.
‘When people start to fuel their exercise correctly for the first time, they start to feel better, and that's because we're boosting their basal metabolic rate, and firing up their internal adaptation process to the training that they were doing,’ he adds.
Why focus on carbs as opposed to protein or fat?
‘Carbohydrates are the primary source of energy for most forms of exercise, so they actually have a bigger impact on the muscle and how it responds to training than protein or fat does in isolation,’ explains Dr Impey.
‘Protein is obviously very important from a recovery perspective. It helps us build, sustain and maintain lean muscle mass, but its acute effects on our day-to-day training and our metabolism are much less than the impact of carbohydrates.’
What are the cons of carb cycling?
If you get it wrong and eat low carb ahead of a heavy training session, that's going to hurt.
‘I think most of us have probably lived that experience of having a busy day at work and not getting enough fuel in and trying to go to the gym in the evening and you’ve just got nothing in the tank,’ says Dr Impey.
‘A lot of people can potentially push through that, and get through the session. But the quality of training is nowhere near what it should or could be.’
Pillai adds that cutting back on the carbohydrates can lead to side effects such as tiredness and low energy, constipation or changes in mood. ‘Carb cycling is not suited for everyone, as some may just prefer a more stable and regular carbohydrate intake with a balanced diet,’ she says.
‘And for some people, if they are not active enough, the higher carb days may lead to weight gain as it can be extra energy taken in that the body is not using.’
Because of the constant changes in carbs, carb cycling is not suitable for those who have an eating disorder or who are underweight, as well as those with medical conditions such as thyroid disease or diabetes, as it can further exacerbate these concerns.
What to eat when carb cycling
If you decide to try carb cycling, remember to seek advice from a professional – such as a nutritionist or dietitian – to help determine the exact number of carbohydrates you need each day based on your workout schedule.
As an example, Dr Impey says if you’ve got a high intensity one-hour gym session after work at five o'clock, then your meal plan for the day may look something like this:
Low carb high protein breakfast: Three egg omelet with spinach and a little bit of feta.
High-carb lunch: Pasta and a banana or a couple of pieces of fruit
Afternoon snack pre-workout: Protein shake.
Post-workout dinner: Risotto with prawns.
‘You wouldn't need as many carbs for dinner as lunch, but you still want to put some carbs back in the system and eat a good amount of protein in the evening, so that you’re recovered and ready to go the next day,’ he explains.
The bottom line
Carb cycling is commonly used by endurance athletes and bodybuilders to adjust carbohydrate intake based on workout intensity and duration. But, it’s also suitable for those seeking fat loss through low-carb eating while staying active. Remember, to tailor carb intake to your exercise routine, it's best to consult an expert.
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