Fasted training doesn't make you faster: Study from researchers including Tadej Pogačar's nutritionist suggests high-carb rides deliver similar results

A study published in the journal Nutrients in Spain has shed new light on fasted training vs high-carb fuelling for cyclists, with the results supporting some long-standing theories about the limited efficacy of fasted training. The paper goes so far as to conclude that fasted training elicits no "superior results" compared to fuelling with plenty of carbohydrates. So should cyclists be indulging in as many carbs as possible before our rides? Perhaps not quite yet... 

This newest paper on the subject of fasted training for cyclists is not exactly groundbreaking in its findings. Numerous studies and pro cycling teams, perhaps most notably Team Sky, have explored the impact of different nutrition strategies, including fasted training, where athletes exercise with reduced carbohydrate availability, and high-carbohydrate diets which utilise liberal carb consumption. The results have been always mixed, but not many have concluded that it doesn't matter so much whether you strictly schedule your carb intake, or indulge in pasta liberally. 

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In this newest study, the researchers from the University of the Basque Country – including Tadej Pogačar's nutritionist Gorka Prieto-Bellver – took seventeen trained male cyclists who were then randomly assigned to two groups. The carbohydrate periodisation (PCHO) group consist of nine cyclists with an average age of 24.8 years and a peak power output (PPO) of 379.1 watts. The high-carbohydrate group (HCHO) included eight cyclists with an average age of 28.2 years and a PPO of 390.6 watts.

All participants were training 15 to 20 hours per week and competing in the U23 national-level cycling categories before the study. After the groups were formed, both the PCHO and HCHO groups then underwent a five-week endurance training program but followed different dietary plans with similar energy intakes. The riders did a few hard workouts every week, with one rest day dotted in, and two gym sessions to complete the load.

The PCHO group completed 13 "low" sessions with reduced carbohydrate availability, based on low-intensity training sessions. These sessions were designed to improve performance and were spread throughout the week. The PCHO group's diet involved altering carbohydrate intake at different times; in other words, they were likely having lower amounts of carbs for low-intensity sessions and more for high-intensity sessions.

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In contrast, the high-carb group performed all training sessions with high-carbohydrate availability before, during, and after exercise – a scenario that already sounds much simpler. 

The HCHO group's diet included consistently consuming high levels of carbohydrates, such as pasta and rice, to fuel their bodies during exercise.

Which worked better, fasted or carb-fuelled training? 

The researchers concluded that there were no substantial differences between the two diet groups in terms of the duration they could exercise before exhaustion, saying: “Periodizing the carbohydrate intake in well-trained cyclists during a five-week intervention did not elicit superior results to an energy intake-matched high-carbohydrate diet in any of the measured outcomes”.

At the end of the five-week test period, both groups showed similar improvements in the maximal lactate steady-state (MLSS) tests, recorded in both watts and W/kg. Both groups also had similar patterns of carbohydrate and fat utilisation during exercise, indicating that the type of diet did not really affect how their bodies used fuel.

All of the participants, regardless of the diet, also showed reductions in body fat and increases in muscle mass.

What's in this for me? 

The findings outlined in this study could indicate that the increasing push for consuming lots of carbs on rides is here to stay – but you should probably take its findings with a pinch of salt. The study's lead author, Dr. Garcia-Pallares, emphasised that "athletes can benefit from either diet as long as they carefully manage their calorie intake and align their diet with their training regimen." In other words, fasted rides are unlikely to disappear from pro training regimes, because it's still a method of controlling calorie intake. 

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What the research does highlight is the importance of individualised nutrition plans tailored to an athlete's specific needs and goals. What works best for one cyclist may not necessarily be ideal for another.

In other words, while the study seems to imply that the more restrictive carb-periodisation doesn't give you that much advantage, it might work for some. It's also worth noting that this study only had 17 participants, all of whom were male. Similar studies conducted with female athletes in this field are still lacking and the little research has shown women's bodies react to fasted training quite differently to men's.