Fasted cardio has been raved about as one of the most effective training methods for fat loss of the last year. But does it really work–or does it just leave you burnt out? WH account manager Camilla Wood put it to the test.
For a dedicated gym enthusiast like myself – think six morning spin sessions a week, fuelled by an espresso and a banana – and someone who likes to try new trends, it’s perhaps surprising that, despite research regularly hailing the health benefits of fasted cardio, I’ve never given it a try. My reliance on caffeine and carbs to get me going had left me unconvinced. Until now.
At a size 10 with an athletic 20% body fat, I’m in good shape – but I’m not at the peak I reached last year for the WH transformation challenge, when my stats read size eight and 14%. With research published by the American Physiological Society revealing that working out pre- breakfast uses stored fat – rather than that bowl of granola – to fuel metabolism, plus Northumbria University saying that fasted cardio can help you burn up to 20% more body fat than post-breakfast training (with no appetite increase), I decided it was time to take the empty-bellied plunge.
The principle is simple: fast overnight and don’t eat or drink before you work out. ‘People respond differently to low blood glucose conditions,’ says sports dietitian Rick Miller*. ‘So it’s best to start off with low-intensity activity. Although many individuals are able to continue their normal training under fasted conditions, it can take time to adapt.’
To go a little easy on myself, I swapped my six usual workouts for four spin classes at Psycle and, with two extra rest days a week, I was pretty excited about the prospect of losing more body fat with less effort. I didn’t find myself lacking energy when I trained first thing at 7am – but my 10am Saturday sessions were a different story. I was starving and found myself regularly (and surreptitiously) turning down the resistance.
And it’s not just me. According to a small study in the British Journal Of Sports Medicine, runners who practice fasted cardio are less likely to be able to run as far for as fast as those who have fuelled up beforehand.
What’s more? ‘There’s a chance of muscle loss if you don’t consume enough protein during the rest of the day, due to the catabolic (muscle breakdown) effect of training under fasted conditions,’ says Miller. Thank God, then, for my protein-rich post-workout breakfast – typically yoghurt and fruit, or a shake.
By the end of two weeks, I had lost an impressive 2kg and 2% body fat. For me, it feels like a totally sustainable change to the way I usually work out – and now that I’ve ditched the caffeine, I have much more energy throughout the day. Fasted cardio? Job done.
Working out tonight? Read our guide to burn calories fast or find out: Does lifting weight help you lose fat?