A Deep Dive into the Controversial New Carbohydrate "Study"

Look, I'll be honest with you: I've been staring at this paper for three days, and I've cycled through every stage of grief. Denial. Anger. Bargaining. Texting Kylee 89 times in a row.

This is the kind of study that makes me want to throw my laptop into a lake, not because it's worthless, but because it's going to confuse a lot of athletes who deserve better information. And also because we got approximately 47 DMs about it.

On social media, a screenshot of this review looks identical to a gold-standard meta-analysis. One is a group of low-carb advocates selecting studies that confirm their priors. The other represents the synthesized findings of hundreds of researchers and thousands of participants. But they get the same real estate in your feed, the same 'interesting!' retweet, the same air of authority. If you (unlike me) had better things to do than spend three days in the methodology mines, you'd glance at the title, think 'huh, maybe carbs ARE overrated,' and scroll on. That's not your fault. But it IS the problem.

So let's do what we do here: dig into the history, examine the science, and figure out what this paper actually proves versus what it claims to prove. Spoiler: those are very different things.

The Paper in Question

The study making waves is called "Carbohydrate Ingestion on Exercise Metabolism and Physical Performance" by Noakes and colleagues, published in Endocrine Reviews in January 2026. It's 50+ pages, cites over 160 studies, and makes some bold claims: that we've had carbohydrate science wrong for decades, that you don't need to carb-load, and that a mere 10 grams of carbs per hour during exercise is sufficient for optimal performance.

If true, this would overturn approximately 60 years of sports nutrition research and practice. Which would be exciting! Science should update when new evidence emerges. But before we throw out every gel and sports drink, we need to ask: what kind of evidence is this, exactly?

Big, if true.

A Brief Detour into How Science Works

Not all scientific papers are created equal. At the top of the evidence hierarchy, you've got systematic reviews and meta-analyses, studies that pool data from multiple trials using predetermined, reproducible methods designed to minimize bias. These are the closest we get to "here's what the totality of evidence actually shows."

At the bottom? Narrative reviews. These are essentially literature summaries where authors select which studies to include and how to interpret them. They can be useful for generating hypotheses or synthesizing complex topics. But they're also easily weaponized to support whatever conclusion the author walked in with. The methodology is basically "I read a bunch of stuff and here's what I think."

This paper is a narrative review. That's not automatically disqualifying, but it means we need to look carefully at who's doing the narrating.

Follow the Money (and the Book Deals)

Every single author on this paper is a known low-carb advocate. Two have written low-carb diet books. Two have ketone-related patents. All five have built careers around the idea that conventional sports nutrition is wrong. That doesn't mean they're wrong, but it does mean we should read their literature synthesis with the same critical eye we'd give to a study on running shoes funded by Nike.

Tim Noakes literally wrote The Real Meal Revolution, a low-carb diet book. Jeff Volek co-authored The Art and Science of Low Carbohydrate Performance. Dominic D'Agostino holds patents on ketone supplements and has financial ties to ketone product companies. These aren't neutral scientists following the evidence wherever it leads, they're people with books to sell, patents to protect, and careers built on the premise that carbs are the enemy.

This is like Kylee publishing a narrative review titled Australian Shepherds: The Goodest Boys and expecting us to take it as unbiased science. Ma'am, we've seen your Instagram.

What They're Actually Arguing

The paper's central thesis hinges on a concept called exercise-induced hypoglycemia, or EIH, when your blood sugar drops during prolonged exercise. The traditional model says fatigue during endurance exercise comes primarily from depleting muscle glycogen (your stored carbs). Noakes and colleagues argue that's wrong: the real limiter is falling blood glucose, and your brain essentially pulls the emergency brake when it senses blood sugar dropping to protect itself from damage.

Their conclusion: if you just keep blood sugar stable with tiny amounts of carbs during exercise (around 10 grams per hour, that's like one-third of a banana or a single swedish fish), you're golden. You don't need to carb-load before events. You don't need 60-90 grams per hour during racing. The whole sports nutrition industrial complex has been lying to you.

Here's the thing: the physiology they're describing isn't wrong, exactly. Blood glucose regulation IS important. The brain-muscle interface IS more complex than simple fuel tank depletion. These are legitimate observations that have been underappreciated in traditional fatigue models.

But they take these interesting physiological observations and hurdle straight past the evidence into conclusions that don't follow. It's the scientific equivalent of noticing that your car needs oil AND gas, and concluding that gas stations are a scam.

The 10 Grams Per Hour Problem

The "10 grams per hour is enough" claim comes largely from a 2024 study by several of the same authors. They had athletes on both low-carb and normal-carb diets exercise to exhaustion while receiving either a placebo or 10 grams of carbs per hour. Both groups improved by about 22% with the carbs. Victory declared: tiny carb doses work!

But here's what they conspicuously did not test: what happens at 30, 60, 90, or 120 grams per hour. They compared "almost nothing" to "slightly more than almost nothing" and concluded that "slightly more than almost nothing" is optimal. That's like testing whether sunscreen with SPF 2 is better than no sunscreen at all, finding that yes, SPF 2 helps, and declaring that SPF 50 is unnecessary.

The research that has actually tested dose-response relationships shows continued performance benefits at higher intakes. A large multi-site study found the greatest performance enhancement at 60-80 grams of carbs per hour. Recent work suggests trained athletes can tolerate and benefit from up to 90-120 grams per hour with appropriate gut training. The dose-response relationship the authors claim doesn't exist... exists.

What the Higher-Quality Evidence Says

Remember how narrative reviews sit at the bottom of the evidence hierarchy? Let's look at what the systematic reviews and meta-analyses (the stuff designed to minimize cherry-picking) actually show.

A meta-analysis examining 50 randomized controlled trials found carbohydrate ingestion during exercise (30-80 grams per hour) improved time trial performance by about 2% and time-to-exhaustion by 7.5%. Two percent might sound small until you realize that in a 3-hour marathon, that's 3-4 minutes. That's the difference between qualifying for Boston and not. Between a podium and a participation medal.

Current consensus guidelines from the American College of Sports Medicine, the International Olympic Committee, and basically every major sports nutrition body recommend 60-90 grams of carbs per hour for events over 2.5 hours. That's six to nine times higher than what Noakes suggests. These recommendations aren't based on vibes or Big Carb propaganda—they're based on decades of controlled trials showing that more carbs, within tolerable limits, means better performance.

A Note on Who Wasn't Studied

The 2024 study underlying many of these claims? All male participants.

If your study design looks like a Bachelorette casting call, your conclusions about human nutrition need a massive asterisk.

This is unfortunately common in low-carb exercise research, and it's a problem because low-energy availability and carbohydrate restriction hit female athletes differently, and often harder.

Chronic low-carb intake is strongly associated with menstrual dysfunction, and the downstream effects on bone health, hormones, and recovery can tank careers. Women have less physiological margin for error here. So when researchers make sweeping recommendations about carbohydrate needs based exclusively on male physiology, they're not just being incomplete, they're potentially steering female athletes toward harm.

We've talked about Relative Energy Deficiency in Sport (RED-S) extensively on the show, and underfueling is one of the fastest routes there. Papers like this one, which suggest that aggressive carb restriction is fine and maybe even optimal, make our jobs harder.

What's Actually Worth Taking From This

I don't want to be entirely dismissive. Buried in this review are some legitimate points worth considering. Blood glucose stability during exercise matters more than traditional models suggested. Individual variation in carbohydrate needs is real, not everyone needs to slam 120 grams per hour, and some athletes genuinely do well with lower intakes. The relationship between liver glycogen, blood sugar, and central fatigue deserves more research attention.

The problem isn't that they're asking interesting questions. It's that they're answering them with a narrative review designed to confirm beliefs they've held for decades, presenting those answers as revolutionary findings that should overturn the scientific consensus.

That's not how science works. Or at least, it's not how science is supposed to work.

The Bottom Line

Should you eat carbs before and during long endurance events? The preponderance of evidence, including the higher-quality systematic reviews and meta-analyses, says YES. For events over 2-3 hours, current guidelines suggest 60-90 grams per hour, adjusted for individual tolerance and gut training. Carb-loading in the days before major events has solid support for improving performance by 2-3%.

Should you reconsider everything you know about sports nutrition because a group of low-carb advocates published a narrative review confirming their existing beliefs? No. Absolutely not.

—Zoë

Key references:

Stellingwerff T, Cox GR. Systematic review: Carbohydrate supplementation on exercise performance or capacity of varying durations. Appl Physiol Nutr Metab. 2014.

Jeukendrup A. A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Med. 2014.

Thomas DT, et al. American College of Sports Medicine Joint Position Statement: Nutrition and Athletic Performance. Med Sci Sports Exerc. 2016.