{"id":68789,"date":"2025-08-15T11:52:09","date_gmt":"2025-08-15T11:52:09","guid":{"rendered":"https:\/\/www.newsbeep.com\/uk\/68789\/"},"modified":"2025-08-15T11:52:09","modified_gmt":"2025-08-15T11:52:09","slug":"i-knocked-back-my-effort-to-fatmax-intensity-for-two-months-heres-what-happened","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/uk\/68789\/","title":{"rendered":"I knocked back my effort to FatMax intensity for two months \u2013\u00a0here’s what happened"},"content":{"rendered":"

This feature originally appeared in the 15 May 2025 print edition of Cycling Weekly, on sale in newsagents and supermarkets, priced \u00a33.35. You can subscribe through this link here<\/a>.<\/p>\n

When CW\u2019s features editor<\/a> emailed me one lunchtime, asking if I\u2019d 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\u2019t merit such a callous appraisal of my physique. Only after I threatened to involve HR did I realise I\u2019d 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 more popular among pro cyclists.<\/p>\n

<\/p>\n

Much has changed in the thinking about long-distance fuelling<\/a> 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\u2019s why fuelling is low-hanging fruit for coaches and nutritionists. But the research never stops, and it isn\u2019t all about the supply end \u2013 the amount of carbs we take on \u2013 but also about how our bodies process them.<\/p>\n

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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 \u2013 practically enough to complete an entire Tour de France. If we could tap into this fat store at will, we\u2019d never again have to bother with on-bike fuelling; but sadly, it\u2019s not that simple.<\/p>\n

When burning energy, the body always draws on a mix of carbohydrate and fat. FatMax refers to the intensity \u2013 down to the last watt, or heartbeat per minute \u2013 at which you\u2019re burning the most fat possible<\/a>. 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.<\/p>\n

My first job was to ascertain the precise intensity at which my fat-burning was at its max. I booked an analysis session at My Vital Metrics<\/a> in London, where consultant Alicia Dodd told me I would need to undergo a DEXA scan and a VO2max test. The former would measure my body fat, while the latter would reveal the proportions of fat and carbs I was using at different intensities.<\/p>\n

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 \u2018healthy\u2019. I was starting to like this place \u2013 I should come here more often \u2013 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.<\/p>\n

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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 \u2013 from which Dodd would extrapolate my all-important FatMax figure.<\/p>\n

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\u2019m burning as much fat as possible \u2013 and it\u2019s where I would spend the lion\u2019s share of my training for the next two months. The intensity is not just easy, it\u2019s mind-numbingly sedate. So what purpose would all this gentle spinning achieve?<\/p>\n

Health over weight loss<\/p>\n

\u201cWe developed FatMax for one reason,\u201d said Asker Jeukendrup, who was part of the team that invented FatMax training, \u201cand that was just to get a complete picture of someone\u2019s physiology. We did one study early on where we trained patients with fatty livers at FatMax, then compared the effects to interval training. They gained more benefit from FatMax.\u201d What about for someone like me whose liver is (hopefully) not clinically fatty? \u201cSince that study, people have been suggesting FatMax is good for this or that, but we don\u2019t have a huge number of studies.\u201d<\/p>\n

Hang on, surely the clue is in the name? Wouldn\u2019t spending more time burning the maximal amount of fat help obliterate the wobbly stuff and improve my tumultuous relationship with the bathroom scales? Not necessarily, according to Javier Gonzales, a professor of nutrition and metabolism at the University of Bath. \u201cThere isn\u2019t really much evidence that specifically exercising at FatMax is any better for fat loss or weight loss than other intensities,\u201d Gonzales told me. \u201cIt\u2019s true that you\u2019re burning proportionately the most fat, and least carbohydrate, at that intensity, but overall fat loss and weight loss in the long term is more dependent on the total number of calories you\u2019re burning.\u201d In other words, racking up a calorie deficit week after week was the most direct route to shifting excess body fat.<\/p>\n

The verdict got worse: by tapping away at 120bpm, I was burning energy at a slower rate and therefore making it harder to accrue a calorie deficit. FatMax was not going to release me from the burden of my buckle-busting midriff any time soon. So how exactly was sitting in this ultra-low zone going to improve my performance on the bike? \u201cThe idea, for those fatty liver patients, was that if you train at an intensity where you burn the most fat, you would also automatically train the fat-burning system,\u201d said Jukendrup. More hours at low intensity would mean I\u2019d develop more mitochondria, potentially helping my body use energy more efficiently.<\/p>\n

As a health dividend, these sessions would fire up my fat-burning system to make my body less reliant on carbohydrate, increasing my metabolic flexibility. Developing more mitochondria should mean improved endurance and faster recovery. OK, I was sold. First, though, I needed guidance as to the optimum number of FatMax sessions to complete in a week, and the optimum duration for each one. \u201cThe longer you go for, the more fat you\u2019ll be burning, and the less carbohydrate you\u2019ll be burning,\u201d explained Gonzales.<\/p>\n

The thought of sitting in the shed at 120bpm for hours on end wasn\u2019t a particularly joyous one. Thankfully, spring came a little early this year, so my road bike came out of hibernation and two months of Operation FatMax began. I soon discovered that sitting at my exact FatMax intensity outside was like herding cats. The slightest gradient change altered my heart rate, and my power graph rose and fell erratically. How precise did I really need to be?<\/p>\n

\u201cFor endurance activities like long, steady cycling or running, your heart rate tends to drift up over time anyway,\u201d said sports scientist and coach Anthony Fletcher, \u201cso a heart rate [target] becomes a moving goal post\u2026 I tend to talk about [FatMax] heart rate generally aligning with Zone 2 for most people.\u201d For Fletcher, FatMax is a range rather than a precise figure, and he advises riders to be guided by their perceived exertion at their prescribed FatMax heart rate, cautioning that \u201cfor some people, it\u2019s an RPE of six [out of 10], for others a three\u201d. Fletcher\u2019s rationale is that keeping within the right \u2018feel\u2019 ballpark makes FatMax training more feasible on the open road.<\/p>\n

\"Steve<\/p>\n

CW’s Steve Shrubsall undergoes lab analysis to set his FatMax intensity <\/p>\n

(Image credit: Future)<\/p>\n

Widened FatMax window<\/p>\n

After eight weeks of FatMax training, it was time to find out if I had become a more efficient cyclist. My follow-up lab test showed that the heart rate corresponding to maximum fat-burning had remained more or less static at 120bpm. However, the window had widened \u2013 up to 136bpm \u2013 meaning I had quite a lot more bandwidth to play with. Fletcher advised that, because I was already relatively well trained, I could not expect more than a marginal gain in eight weeks.<\/p>\n

As interesting as the experience has been, I remain ambivalent about FatMax training. If its purpose is to improve the health of unfit individuals, why should I incorporate it? Everyone already knows that low-intensity exercise is fundamental for building endurance, and as Fletcher commented, \u201cmost of the best cyclists in the world have been doing this stuff for decades\u201d.<\/p>\n

For practical ease, can\u2019t we just carry on doing plentiful Zone 2 riding? We may not be oxidising fat with the pinpoint precision of a FatMax heart rate, but, as my follow-up test showed, my window for optimal fat-burning is relatively wide, spanning 120-136bpm. Rather than fixating on my heart rate monitor, I\u2019m content to let my fat-burning range be guided by feel. As for weight loss, well, that\u2019s always going to start and end in the kitchen.<\/p>\n

\"Male<\/p>\n

(Image credit: Future)<\/p>\n

Feels too easy? Your physiology doesn’t care<\/p>\n

Canadian coach Steve Neal (stevenealperformance.com) explains why FatMax training matters \u2013 even if its benefits aren\u2019t immediately apparent.<\/p>\n

The amount of FatMax training I prescribe depends on an athlete\u2019s level of fitness. A really fit pro might be pushing 280-300 watts at just 65% of their max heart rate. On the other hand, with a beginner, if their FatMax is under 150 watts, that\u2019s too low a training stimulus, so instead I start them with a lot of Zone 3 work \u2013 because they\u2019re not yet fit enough to make full use of FatMax training.<\/p>\n

The riders I test are always surprised by how low an intensity their FatMax is. But remember, our physiology doesn\u2019t care what we perceive the work to be. If you\u2019re riding at FatMax, the energy is coming predominantly from fat \u2013 it\u2019s working. We want to see a rider\u2019s FatMax improving relative to their threshold or VO2max.<\/p>\n

In the case of CW\u2019s Steve, his FatMax of 205 watts is just 43% of his five-minute power of 472 watts. I\u2019d want to see it closer to 60-70%. Currently, his workload while burning fat is relatively low. He\u2019ll only improve it by doing more training at low, FatMax intensity \u2013 you have to push it up from below, you can\u2019t pull it up from above. This would, however, mean training upwards of 10 hours a week.<\/p>\n

As an example, one rider I work with had a FatMax of 175 watts when I started coaching him. A year later, his FatMax was still 175 watts, but his fat utilisation at that wattage was 40% higher. His crossover point, from burning mostly fat to burning mostly carbs, had risen to 215 watts. This meant that when he took part in races of three hours or longer, he was much better because he was sparing carbohydrate. This is why FatMax testing matters.<\/p>\n

FatMax in numbers<\/p>\n

45-65% \u2013 percentage of VO2max corresponding to FatMax intensity in most people (or approximately 55-75% of FTP)<\/p>\n

60-70% \u2013 heart rate range, as percentage of HR max, in which fat-burning is greatest (broadly aligning with Zone 2)<\/p>\n

0.8-1.5g\/min \u2013 rate at which fat-adapted athletes can oxidise fat, compared to 0.3-0.6g\/min in non-adapted people<\/p>\n

20-30% \u2013 percentage reduction in muscle glycogen usage during submaximal exercise in fat-adapted athletes<\/p>\n

100,000 calories \u2013 stored in body fat, compared to less than 2,000kcal in glycogen<\/p>\n","protected":false},"excerpt":{"rendered":"This feature originally appeared in the 15 May 2025 print edition of Cycling Weekly, on sale in newsagents…\n","protected":false},"author":2,"featured_media":68790,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[37],"tags":[4985,101,56,54,55],"class_list":{"0":"post-68789","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-cycling","8":"tag-cycling","9":"tag-sports","10":"tag-uk","11":"tag-united-kingdom","12":"tag-unitedkingdom"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/68789","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/comments?post=68789"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/68789\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media\/68790"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media?parent=68789"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/categories?post=68789"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/tags?post=68789"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}