We\u2019re seeing improved performances, faster recovery, and fewer bonks just, seemingly, by slamming down bars, gels, and drinks all to hit the magic number of 120 grams of carbs (or more) per hour. That\u2019s what many publications<\/a>, nutrition brands<\/a> and retailers<\/a>, and influencers (you know who they are) are also saying.<\/p>\n Call me a cynic, but I\u2019m inherently skeptical of any brand, retailer, or individual pushing an agenda that serves their bottom line.<\/p>\n You may be desensitized to this 120 number now. But lest we forget that it\u2019s a shocking leap from just a decade ago, when the goal was to take in 30 to 60 grams of carbs an hour, max. The goal, scientists believed, was to preserve muscle and liver glycogen. Science has progressed<\/a> since then, largely thanks to the finding that precisely combining various forms of carbohydrates<\/a> allows for higher absorption rates.\u00a0And yet, current scientific recommendations top out at 90 grams of carbs per hour<\/a>.<\/p>\n So what\u2019s the deal with 120 grams of carbs and more? It\u2019s seemingly working for some pros, what does that mean for most of us? My curiosity led me to a pair of experts who have done their homework: Roxanne Vogel, PhD in exercise physiology and director of R&D at GU Energy Labs, and Paul Booth<\/a>, a PhD candidate and nutrition coach for Tom Evans<\/a> and Ruth Croft<\/a>, who both won the 2025 Ultra-Trail du Mont-Blanc<\/a>.<\/p>\n Carbohydrate Complexity Booth brought us straight back to the science, which he says, is not a fluke.<\/p>\n \u201cThere\u2019s a pretty big emphasis right now on 120 grams as a catch-all for anyone,\u201d Booth says, \u201cbut the data isn\u2019t there. Follow the science, not what someone is saying online. No one has found any benefits over 100 grams, if not closer to 90. One of the most famous studies<\/a> shows that the optimal amount is actually 80 grams. Our lab found that 90 was best and dropped off above that.\u201d<\/p>\n Not only is there an upper limit to performance gains, Booth is saying, but performance actually declines once you carb up too high.<\/p>\n The super-high carb dogma leans on simple yet tenuous logic: More is more. Research shows this is true for up to around 90 grams, but above that is where things start to get murky. Making the case for 120 requires cherry-picking studies or relying on anecdotal evidence\u2014in short, pseudoscience. For example, some data on sub 2:30 marathoners<\/a> suggests substrate oxidation improves above 90 grams, but the study doesn\u2019t correlate it to improved performance outcomes. You have to connect those dots yourself, which comes with its own set of risks.<\/p>\n Research on non-elite runners shows an even cloudier story. Amateurs who are trying to imitate pros are likely over-carbing, with oxidation efficiency\u2014your body\u2019s ability to burn carbs and fat for fuel\u2014going down from 86% at 90 grams to 75% at 120<\/a>. This difference may sound minor, but in long races like ultras it adds up: 13 unoxidised grams of carbs per hour vs 30 is a lot of carbs just floating around in your gut.<\/p>\n \u201cThere isn\u2019t a single peer-reviewed study that shows performance benefits over 90-grams of carbs,\u201d Vogel says. \u201cIt costs more, risks more, and has no proven performance benefit.\u201d<\/p>\n In fact, there\u2019s some evidence that going above 90 grams accelerates muscle glycogen depletion and reduces performance.<\/p>\n One Size Does Not Fit All<\/p>\n I\u2019m generally skeptical of one-size-fits-all recommendations and sure enough, the science is much more nuanced, too. One study on personalized carbohydrate fueling<\/a> emphasizes that the amount individuals should take varies significantly, emphasizing that fueling based on individual oxidation rates outperforms high-dose blanket strategies.<\/p>\n \u201cEmerging research<\/a> shows significant variability due to factors like body size, exercise intensity, and sex,\u201d Vogel says. \u201cBody size is positively correlated with the ability to oxidize ingested carbs, suggesting that traditional guidelines are over-feeding some while under-fueling others. Intake should be individualized based on body size, with a target of approximately 0.7 grams of carbs per kilogram of body weight per hour.\u201d<\/p>\n Evidence from two of the best ultra runners in the world\u2014Tom Evans and Ruth Croft\u2014supports this as well.<\/p>\n \u201cTom [Evans]\u2019s average intake during UTMB was 94 grams and Ruth [Croft] was roughly at 90 grams,\u201d\u00a0 Booth says. \u201cIn lab tests with Tom we found that he could oxidize 1.7 grams per minute at his max, which is quite high. For his pace at UTMB, we didn\u2019t need to be at that level all the time because it would be over-fueling. Instead, we varied it based on the demands of the course, feeding him more before sections that he would dig deeper, then back down to give his gut an easy section.\u201d<\/p>\n Not only is the gold standard different from athlete to athlete, then, but also within each athlete depending on the context. Fueling dynamically with your output and the demands of the course may often be the best course of action.<\/p>\n Personalized trials also show a lower rate of perceived effort and less stomach fullness with under 90 grams, which is associated with GI discomfort. This makes sense, as a personalized dose means there are fewer unoxidised carbs accumulating in your gut. In other words, aiming for a blanket 120 carbs per hour increases the odds you\u2019ll have GI issues (and DNF), instead of improving your finishing times.<\/p>\n \u201cThere may be some utility for world-class athletes in multi-day events where recovery is challenging and the opportunity to fuel is limited, but gut training is required,\u201d Vogel says. In all other cases, \u201cthere is no point in ingesting carbohydrates in sports drinks and gels that aren\u2019t metabolized, especially for non-elite athletes. It just increases the risk of gastrointestinal issues.\u201d<\/p>\n Breaking It All Down<\/p>\n A 2020 paper focused on recovery<\/a> kickstarted the carb revolution in trail running. The lead author, Aitor Viribay, was working for Ineos Grenadiers at the time and pulled the concept from cycling. Since then, the Western States 100<\/a> has seen 14 of its 15 fastest female times and 12 of the 15 fastest male times, which is not a coincidence. The increase in carbs (along with training and technological improvements<\/a>) has made a huge impact, but there are limits to everything.<\/p>\n My broad takeaway from talking with Vogel and Booth and reading the research is this: There is no need for most athletes to strive for such astronomically high carb intakes, and in some cases it may actually be to their disadvantage. As a general rule of thumb, imitating everything a pro athlete does isn\u2019t ideal for most amateurs and in this case, over-fueling comes with its own risks, namely GI issues.<\/p>\n The big problem with 120 grams per hour is that it is becoming the default baseline, not a rare outlier for just a few world-class athletes. Most runners should start with 80 or 90 grams per hour (which, again, is three times the recommendation from only a decade ago!) and then, if possible, get individualized testing to adjust as needed.<\/p>\n That\u2019ll do a lot more good than listening to the influencers and brands who are trying to sell you more stuff.<\/p>\n","protected":false},"excerpt":{"rendered":"Updated December 2, 2025 10:11AM The carb revolution is upon us, y\u2019all! Runners, triathletes, and cyclists are breaking…\n","protected":false},"author":2,"featured_media":608439,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4318],"tags":[105,4434,136147,190326,190327,136152,190328,190329,132984,16,15],"class_list":{"0":"post-608438","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-nutrition","8":"tag-health","9":"tag-nutrition","10":"tag-parent_category-nutrition-health","11":"tag-tag-carbohydrate-intake","12":"tag-tag-carbohydrates-for-runners","13":"tag-tag-evergreen","14":"tag-tag-fueling","15":"tag-tag-fueling-for-runners","16":"tag-type-article","17":"tag-uk","18":"tag-united-kingdom"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@uk\/115652750468043147","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts\/608438","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/comments?post=608438"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts\/608438\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/media\/608439"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/media?parent=608438"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/categories?post=608438"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/tags?post=608438"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\n![\"Ruth](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2025\/12\/17-PM_-Ruth-Croft-Vallorcine-2025-UTMB.png\"\/)
With the help of her nutrition coach Paul Booth, Ruth Croft used a dynamic fueling strategy en route to winning the 2025 UTMB. (Photo: Peter Maksimow)<\/p>\n![\"David](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2025\/12\/UTMB_OCC_Lukewebstr103-scaled.jpg\"\/)
What the scientists say: Start with 80 to 90 grams of carbs an hour and go from there. (Photo: Luke Webster)
\nTummy Troubles<\/p>\n