This feature originally appeared in the 15 May 2025 print edition of Cycling Weekly, on sale in newsagents and supermarkets, priced £3.35. You can subscribe through this link here.

When CW’s features editor emailed me one lunchtime, asking if I’d like to investigate FatMax, I almost choked on my pork pie. What exactly was he insinuating? OK, I had to punch a couple of extra holes in my belt over the winter, but surely that didn’t merit such a callous appraisal of my physique. Only after I threatened to involve HR did I realise I’d been hasty. Although FatMax sounds like the street name of a portly American mobster, it in no way pertains to excess blubber. It is, in fact, a training method that is growing ever popular among pro cyclists.

Much has changed in the thinking about long-distance fuelling over the past decade, principally a paradigm shift in top-end carbohydrate intake, the amount our bodies can absorb and use per hour. The more fuel you can shovel, the longer and faster you can ride. That’s why fuelling is low-hanging fruit for coaches and nutritionists. But the research never stops, and it isn’t all about the supply end – the amount of carbs we take on – but also about how our bodies process them.

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The carbs we consume on the bike are mostly short-chain sugars, usually glucose and fructose. But the body holds a store of fuel in the form of long-chain glycogen and fat. Even the leanest athletes have some 100,000kcal worth of fat at their disposal – practically enough to complete an entire Tour de France. If we could tap into this fat store at will, we’d never again have to bother with on-bike fuelling; but sadly, it’s not that simple.

When burning energy, the body always draws on a mix of carbohydrate and fat. FatMax refers to the intensity – down to the last watt, or heartbeat per minute – at which you’re burning the most fat possible. Having spent the winter in my shed doing high-intensity efforts that rely almost entirely on glucose, this was an excellent excuse to explore how to make the most of my underexploited fat stores. Switching to FatMax training would, I assumed, be the ideal opportunity to lose some fat.

The entirely painless DEXA scan produced a body fat reading of 17%, which came as a pleasant surprise. Despite tipping the scales at over 90kg, my body composition got the thumbs-up as ‘healthy’. I was starting to like this place – I should come here more often – but now it was time for the main event. Feeling at home aboard a Wattbike Atom, I was confident of doing myself justice in the VO2max test. But then the mask arrived.

With the gas-collecting apparatus sucking at my face like a determined leech, the outlook became less cheery. I was beginning to understand why Darth Vader seems so pissed off all the time. Suppressing panic, I began pedalling and, several wattage increments later, I maxed out, fiercely expelling my lungs into the gas bags – from which Dodd would extrapolate my all-important FatMax figure.

After studying the resulting data, the respiratory exchange ratio (RER) where fat was used at an optimum, corresponded to 205 watts at 120bpm. This is my FatMax, where I’m burning as much fat as possible – and it’s where I would spend the lion’s share of my training for the next two months. The intensity is not just easy, it’s mind-numbingly sedate. So what purpose would all this gentle spinning achieve?