Fasting before riding is a training secret of the pros – so should we all be racking up the kilometres before we hit the Weet-Bix?
Tradition – and common sense – dictates that you should fuel up before, during and after training rides, but increasingly coaches are prescribing ‘fasted’ rides where you train first thing without any breakfast, as a means to improve performance. Is this something we should be adopting or is it all empty promises?
It’s a big IF
First, it’s worth looking at the concept of ‘intermittent fasting’ (IF), which basically means not eating at strategic times, rather than going on hunger strike. ‘Intermittent fasting has grown in popularity as an effective method of weight loss and maintenance,’ says nutritionist Sarah Schenker. ‘Various IF regimes have been created, including the alternate fast day, the 5:2 – fasting for two days of the week, eating for five – and the 16:8, which involves fasting for 16 hours of the day.’
Intermittent fasting relies on not gorging yourself when you are allowed food, in which case the results are interesting. ‘A number of studies in humans have been performed showing positive results for both weight loss and health,’ says Schenker. ‘Results from trials performed in normal-weight men and women showed that a three-week period of an alternate fast-day regime lowered bodyweight by 2.5% and also decreased triacylglycerol concentrations and increased HDL-cholesterol concentrations.’
Triacylglycerol is a potentially harmful compound made up of fatty acids – it’s the chief constituent of fats and oils – while HDL is a ‘good’ cholesterol that removes ‘bad’ cholesterol from the bloodstream. So if it can be used to your benefit, the next question is how controlled fasting can be used, safely, as part of a training regime.
Training in a ‘fasted’ state is not a fad diet. It’s a strategic training method where ‘carbohydrate fuelling’ is completed after training rather than before. Weight loss comes into it if only to reduce your body fat percentage to help improve performance, not to get you a round of applause at Weight Watchers.
Fact or fiction?
The theory is that fasted training further enhances the ‘aerobic adaptations’ – your body’s ability to improve its aerobic exercise performance over time – that occur as a result of training by increasing mitochondria. These exist in each cell to produce its supply of adenosine triphosphate (ATP), which is used as a source of chemical energy.
‘One of the goals of endurance training is to increase the mitochondrial mass in muscle,’ says James Morton, senior lecturer in exercise metabolism at the UK’s Liverpool John Moores University. ‘The more you have, the greater your aerobic energy. Fasting signals an increase in mitochondria to increase training adaptation.’
But is it scientific? ‘In 30-odd years I’ve never seen anything scientific written down,’ says senior coach Ian Goodhew. ‘I’ve just heard stories. The pros do it, but they’re in a controlled environment.’
‘It has only really entered the realms of sports science in the past 10 years,’ says Morton. ‘But there have been numerous studies – at Liverpool John Moores, as well as in Australia, Denmark, Belgium and Canada – to show that it works.’
Many nutritionists also believe in the benefits. ‘If you train “low” – on limited carb stores – you optimise your fat mobilisation as a source of energy,’ says Schenker. ‘The more you do it, the more efficient the body becomes at using a higher percentage of fat as a fuel source.’ This is beneficial because the body’s stores of fat far exceed those of glycogen, so if a cyclist becomes more able to burn fat as fuel, their endurance increases.
Drew Price, performance nutritionist and author of The DODO Diet (or Day On Day Off Diet), agrees: ‘The body will generally tend to burn more of what you show it. Endurance athletes with their high intake of carbs tend to shift towards burning carbs. Fasting means there’s no “easy” carbs entering the blood from the gut, but more importantly the lack of nutrients allows for the increase in fat burning because you get a spike in growth hormones.’
There is, however, a fine balance to strike. ‘You need to feed on protein to preserve muscle mass and restrict carbohydrate intake,’ says Morton. ‘You don’t have to fast altogether – you can go a long way on a protein shake or scrambled eggs without the toast – and you shouldn’t employ this technique too much because you can get ill or pick up infections. Carbs fuel the immune system.’
Ultimately, the theory is that, by training ‘low’ but not at a detriment to your health, your body adapts to the demands of training without fuel and come race day, when you’ve eaten normally in the build-up, the extra fuel will improve your performance.
Working behind the scenes
The claimed benefits don’t end there. ‘This type of training increases the body’s production of growth hormone, which is good for general health and recovery, as well as fat burning,’ Price says. ‘It can also lead to improved insulin sensitivity and better mitochondrial health.’ Increased insulin sensitivity means less insulin is required to store carbohydrates in your cells, and is good for all-round health.
During fasting training, the absence of carbs and proteins in your system means reduced insulin output. This, along with the gradual running down of the glycogen stores in the muscle and liver, resensitises the cells to insulin in specific tissues. ‘It’s like a caffeine holiday where you resensitise yourself to caffeine by not having it for a bit,’ says Price.
Goodhew counters that your body won’t produce insulin when you’re riding hard anyway. ‘If you eat an energy bar while sat down before training, your body will produce insulin (or you’d be diabetic). If you have it on a ride your body is in training mode and won’t produce insulin, especially if you’re sprinting or climbing.’
‘There are other benefits too,’ Price adds, ‘such as increased production of sirtuin, proteins that protect cells, and increased autophagy – the clearing out of cellular junk extending the life of the cell. These add up to better general health, better power-to-weight ratio and advantages for both riding and recovery in terms of fuel usage and storage.’
Should we skip breakfast?
‘The theory is sound but there’s no one prescription for each person – the frequency of these fasts should be set by your needs,’ says Price. ‘For the athlete, the frequency is going to be a lot lower than the average Joe looking to lose some turkey weight.’
‘Most experts recommend a middle ground,’ says Schenker, ‘so training on
low carbs to improve fat usage but still supplying enough carbohydrate for bouts of cycling when you might be working at 80% VO2 max.’
However, Goodhew isn’t so certain. ‘People think, “This is what the pros do so this is what I need to do,” even if they are only targeting fairly short sportives. But it’s not,’ he says. ‘It worries me slightly. Emotionally, this could kill you by making you tired, stressed and depressed. If you bonk a couple of times your head would fall off.’ Not literally, of course.
Is it for you?
‘Maybe yes, maybe no,’ says Price. ‘Most people who need something easy to lose the fat can just get into it, whereas athletes need to focus on what they’re eating and then work the fasting into that. Diet first, then fasting. Start with one fast per week and make sure it’s on a rest day.’
It’s the ‘something easy to lose the fat’ that concerns Goodhew. ‘If you need to lose weight there’s lots of other things you can do,’ he says. ‘Eat healthily, and cut salt from your diet because salt retains water.’
Perhaps there is a middle ground, if the benefits beyond losing fat sound appealing. ‘You need to experiment – don’t try it before a big race!’ says Schenker. ‘Give yourself time, start slowly and play around with timings – for example you might find you feel very hungry and then the feeling passes. Just be prepared in case you bonk.’
And that’s the key. ‘There’s no one-size-fits-all, and you need to consider your training periodisation,’ says Morton. One thing all the experts agree on is that you should never fast before a long or high-intensity ride – only for short or low-to-medium rides.
‘Most people do their longest training ride at the weekend. Fuel up for this with breakfast, and take energy gels with you. You can consider this practice for your racing strategy – train high to race high. Then try adding a low-intensity ride in a fasted state.’
And there’s a new twist. ‘There’s a theory known as “sleeping low”. Don’t eat, then go for a ride at 8pm. Take on some protein but low carbs, sleep and then exercise again in the morning. What happens when you rest is as important as what happens when you train because studies have shown that your muscles recondition themselves when you rest – and carbohydrate suppresses this.’
So there are benefits. Just remember that, as Morton says, ‘the pros are adapted to this and in tune with it. Get advice from a coach on your training plan, but it does work.’
Nil by mouth
Expert tips on how to fast and train safely
For short fasts (less than 17 hours)
Eat a normal balanced evening meal and then have no breakfast before your morning training ride. This is a good way to burn fat. It’s important to pack in enough nutrition after your training session to support health, recovery and maximise performance gains.
- Drink a calorie-free electrolyte drink before riding.
- Break the fast at the end of the training session (or before the end according to how you feel).
- After the session, take on liquid nutrition first: whey protein and a sports drink.
- Follow this quickly with a large wholefood meal.
For longer fasts (more than 17 hours)
These should only be done on rest days. The idea here is to maximise the advantages of the fast and also make sure every riding session is a quality one – so fasting and training take place on different days.
- Keep fasting days and training days separate.
- Start with one per week or even two or three per month.
- To get the maximum benefit have a total calorie fast for 20-24 hours.
- This means water, a little tea and coffee, but no milk/sugar/sweetener, etc.
You need to plan the duration and frequency of your fasts according to your stress levels, sleep patterns and general wellbeing. Fasting, like exercise, causes stress and so the amount you do depends on your condition and goals.
- Ensure your whole diet is of high quality and sufficient to support your training.
- Getting enough sleep is critical to success too.
- To aid recovery, add a little extra post-training nutrition on your training days.
- Be cautious with the frequency of fasts, especially the fasted training sessions.
- Reduce salt intake.
- Reduce carb intake for greater muscle reconditioning.
Fast and furious
Performan nutritionist Drew Price passes on some tips from his own experience of fasted training
‘First, this sort of training isn’t as bad as you might think,’ says Price. ‘Short sessions are the easiest but longer recovery rides with low wattage are OK too. I’ve found that separating longer fasts ( more than 18-20 hours) from training usually gets the best results as you balance the advantages of fasting with the advantages of being in a fed state for training. Shorter fasts (less than 18 hours) are more suited to training. Either way hydration is a must. When I’ve been fasting for a while before training I’ve found I wasn’t holding as much water because I’d taken on less carbs and electrolytes. Some form of diluted electrolyte product in the hours before training is useful. ‘Always eat after your ride, so time your training to come before the break in the fast. You’ll be a bit hungry by then!’