The old recommendation for sports nutrition guidelines suggested roughly: -30–60 g/hour for events lasting 1–2.5 hours. -Up to 90 g/hour for events over about 2.5–3 hours, using multiple transportable carbohydrates (typically glucose plus fructose). https://pubmed.ncbi.nlm.nih.gov/41759826/ People thought around 90 g/hour was close to the physiological ceiling. (I actually remember these guidelines when I was doing a lot of cycling back in the late nineties and early two thousands). What's happening now? Elite cycling, Ironman, marathon, and ultra-endurance athletes have started experimenting with: 100–120 g/hour 120–150 g/hour Some elite professionals even report 180–200 g/hour in specific events. The key isn't simply eating more sugar. It's: -Training the gut, -Using optimized glucose/fructose ratios, -Maximizing absorption, -Maintaining blood sugar, -Preserving glycogen, -Delaying fatigue over many hours. https://research.birmingham.ac.uk/en/publications/from-metabolism-to-medals-contemporary-perspectives-and-revisitin/?utm_source=chatgpt.com The research is catching up. A recently published study compared water, 60 g/hour, and 120 g/hour during three hours of cycling. https://onlinelibrary.wiley.com/doi/10.1111/sms.70326?utm_source=chatgpt.com The 120 g/hour resulted in better preservation of critical power than either 60g/hour or water, suggesting that higher carbohydrate availability improved durability during prolonged exercise. A 2026 review reached the following conclusion: The needle is clearly moving toward 120 g/hour for many elite endurance athletes. There are even reports of 120–200 g/hour in competition. It's important to mention that evidence does not yet show that "more is always better." The best-supported upper limit today is roughly 120 g/hour for trained athletes, and responses are highly individual. research.birmingham.ac.uk/en/publications/from-metabolism-to-medals-contemporary-perspectives-and-revisitin/?utm_source=chatgpt.com Now understand science isn't saying: "Everyone needs 120 grams." It's saying: "For certain elite athletes performing at extreme workloads, higher carbohydrate intake can improve performance." This destroys the "metabolic flexibility" argument. Think about it. Tour de France riders are arguably among the most metabolically efficient humans on Earth. They're lean. Their mitochondria are extraordinary. Their fat oxidation rates are phenomenal. If anyone were "metabolically flexible," it's them. Yet, many are intentionally consuming 100–12 or more grams of carbohydrate every hour during races. Why? Because they suddenly became metabolically broken? Of course not. Because the demands of the event exceed what fat oxidation alone can support while maintaining winning power output. Imagine someone says, "If your truck needs premium fuel to tow 20,000 pounds, then your engine is inefficient." That's the opposite of what's true. The engine isn't weak. The workload is crazy. The fuel matches the demand of the output. That's exactly what's happening in elite endurance sports. And perhaps in workouts or races that are strength-based as well that also challenge aerobic capacity. Think Hyrox or CrossFit games-style stuff. Or maybe a GoRuck event lasting 12 hours or more? This definitely sparks my curiosity. Now someone will get this twisted. I am not saying "Tour riders eat 120 grams an hour, therefore everyone should." That's a weak argument. I'm merely pointing out that If the most metabolically fit athletes on Earth deliberately consume massive amounts of carbohydrates to maximize performance, then the claim that using carbohydrates automatically proves metabolic inflexibility simply doesn't hold up. My usual boring disclaimer: Of course, there are some out there performing at a high level over long duration on carnivore or ketogenic diets. Those at the pointiest tip of the spear, are finding record-breaking success pushing the limits of energy intake from precise and calculated intake of glucose/fructose per hour. The goal isn't to prove you can survive on less fuel. The goal is to perform at your highest level. Those aren't always the same thing. Let me be very clear: this isn't an argument that everyone should start pounding sports drinks or eating 100 grams of carbohydrates every hour. It's an argument against the idea that using carbohydrates somehow proves you're metabolically unhealthy or "doing it wrong." The best endurance athletes on the planet have extraordinary metabolic flexibility, yet they strategically use massive amounts of carbohydrates when the demands of competition require it. Why? Because they fuel the mission—not an ideology. Whether your mission is building muscle, running an ultramarathon, completing a GORUCK event, or simply staying healthy after forty, your nutrition should serve your performance—not your identity. There is a certain Tour de France cyclist currently dominating the 2026 Tour. He already has four wins under his belt. He is adopting this strategy. Many are already calling him perhaps the greatest of all time.  I can say anecdotally that when I did my 50k Mountain Ruck Challenge in 2024, I was consuming roughly 30 to 40 g of carbs per hour. I noticed a definite advantage. I also found that carb cycling for my 2025 bodybuilding competition, after four years off, mind you, served to be by far the best strategy for me to recomp and maintain lean muscle mass while achieving my lowest level of body fat ever in competition. Now that I am training for a 12-hour GoRuck event that will be physically challenging in September, I intend to experiment with this tactic and find my sweet spot on my long rucks each week. My long rucks are between two and six hours. Through this experiment, I hope to find my own personal sweet spot that will help me get serious traction going into my event.
I will be documenting this journey on my YouTube channel. Be sure to subscribe and follow along. Subscribe here: www.youtube.com/@RobGoodwinFitness
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 Within the past year, I've had many ketogenic/carnivore influencers, as well as many others in the comments, saying to me, "If you need carbs before or after training, you're not metabolically flexible."
My short answer: "Using carbohydrates strategically doesn't prove metabolic inflexibility any more than using a higher gear on a bicycle proves your legs are weak. Metabolic flexibility means I can efficiently burn fat when the workload is low and carbohydrates when the workload is high. I'm not married to either fuel source—I use the one that best matches the job." Now this is usually the part where I have to give my usual disclaimer so I don't get relentlessly attacked and people in the carnivore/keto space don't lose their minds. If you are thriving on a ketogenic or carnivore diet and getting everything out of it that you expected, then by all means continue to do so. I'm not here to say there is one size that fits all. I'm simply saying that there are many ways to skin a cat, and while one person may thrive in one direction, others may thrive in another. My insight is from one who has experimented deeply with both in a hard training and high output environment for many, many years. Literally decades. Many people in this internet age have shiny object syndrome and get caught up in online echo chambers. Free yourself. Onward... Let's break it down. This is what "metabolic flexibility" actually means. Metabolic flexibility is simply the ability to efficiently switch between fat and carbohydrate depending on what's being asked of the body. A metabolically flexible person can:
Being able to use carbs isn't evidence that you're metabolically inflexible. It's evidence that your metabolism works. I made the mistake of believing that I needed to completely exclude a major macro nutrient and tirelessly work on exercise efficiency in order to build "metabolic flexibility". I did this for not just weeks or months, but I did it for literally years at one point. And found for my body and my level of output, it never quite reached the level that I desired or found completely sustainable. And I've experienced the same with dozens and dozens of clients over the last year especially. Real data from real people. Carbs are a tool, not a requirement. No, carbohydrates are not required to build muscle. No, they aren't required to survive. But neither is larger amounts of protein, copious amounts of fat. Neither are barbells or lifting straps. Neither is creatine. Neither is refrigeration nor air conditioning. We use tools because they improve performance And quality of life. The amount of protein actually required to sustain life is extremely small. But we're not looking for the absolute minimum effective dose to not die. Rather, we're looking for the precise amount required to generate the greatest result. There is no human life requirement for exogenous saturated fat either. But many carnivore and keto influencers say that substantial amounts are an absolute necessity. And I'm sure it is for their level of output and the greatest quality of living. The truth is, the only dietary fat needed for human survival is Linoleic acid (omega-6) and Alpha-linolenic acid (omega-3). The question isn't: "Can I survive without carbs?" The question is: "Can strategically timed carbohydrates improve my performance, recovery, muscle retention, and training volume?" For many athletes the answer is yes. Exercise physiology hasn't changed When you perform:
That's not an opinion. That's basic exercise physiology. Fat oxidation is incredible, until intensity rises. Then carbohydrate becomes increasingly important. Being fat-adapted isn't the same as being optimal. A carnivore athlete may complete a hard workout. A mixed-fuel athlete may complete that same workout with:
Context matters. A 45-minute Zone 2 ruck? Probably don't need carbs. A twelve-hour GORUCK Tough challenge? Maybe (and I have found through exhaustive experimentation that for myself this will be an x-factor). A brutal leg workout with 20 hard sets? Quite possibly. A bodybuilding prep where every ounce of muscle matters? Absolutely worth considering and one can make the argument that it would be absolutely optimal. Fuel should match the demand. The irony is many influencers define metabolic flexibility as: "I never need carbs." That's actually the opposite of flexibility. Real flexibility is: "I can function extremely well on fat, and I can also utilize carbohydrate efficiently when it gives me an advantage." That's flexibility. The goal was never to prove you can suffer on the least amount of fuel possible. The goal is to become stronger, faster, healthier, and more capable. Real metabolic flexibility isn't refusing carbohydrates or worshipping them—it's having the ability to efficiently use both fat and carbohydrates depending on what the mission demands. The physiology is settled. The debate isn't about biology anymore; it's about ideology. I'll choose performance every single time. You choose what's best for you, and then we can all get along. *Want to fast track your results and become more dangerous again? Check out my Iron Forty programs or get my popular new book Iron Forty available for download immediately at www.robgoodwinfitness.com  Somewhere along the way, a lot of people stopped trying to become dangerous. They settled for comfortable.
Comfortable jobs. Comfortable routines. Comfortable bodies. Comfortable excuses. Then they wonder why life feels flat. The world doesn't need more comfortable people. It needs capable people. Dangerous people. Not dangerous because they're angry. Dangerous because they're prepared. Here are five ways to start becoming that person again. 1. Lift Heavy Things Muscle is your armor. It is the currency of life. Strength isn't just about looking good in a T-shirt. It's about earning confidence every time you walk into a room. The "Freak in the Room". Strong people carry themselves differently because they've carried hard things. If you're over forty, building muscle isn't optional anymore. It's one of the greatest investments you can make in your future. The term "harder to kill" has become a bit of a cliche. It should be your obsession. Armored. Resilient. Tempered. Scarred. 2. Carry Weight and Walk Throw a ruck on your back. Grab heavy dumbbells and farmer's carry them. Move. There's something primitive about carrying weight over distance. It builds your lungs, your grip, your legs, your back—and maybe more importantly, your character. When life gets heavy, it helps if you've practiced carrying heavy things. 3. Do Things That Suck on Purpose Cold mornings. Steep hills. One more rep. One more mile. Repetitive meals. Deadlift, push, pull, squat. Learn to shoot a firearm. Work a heavy bag. Nobody accidentally becomes resilient. You build it by choosing discomfort before life chooses it for you. Your comfort zone is expensive. It quietly steals your confidence while convincing you you're safe. 4. Keep Your Word to Yourself This might be the biggest one. Stop breaking promises to yourself. If you say you're training at six AM... Train at six AM. If you say you're eating clean... Eat clean. Every promise you keep deposits confidence. Every promise you break makes you question yourself a little more. Discipline isn't punishment. It's self-respect. 5. Become Someone Others Can Lean On Real strength isn't selfish. Become the person who carries groceries without complaining. The one who helps someone move. The one who stays calm when everything goes sideways. The one who can protect, provide, encourage, and endure. The strongest people don't intimidate everyone around them. They make everyone around them feel safer. It was Jordan Peterson that said "men need to be monsters but know how to control it." And he was absolutely right. Looking dangerous is easy. Filters can do that. Actually becoming dangerous takes years of sweat, consistency, discipline, and choosing hard things long after the excitement wears off. Train your body. Sharpen your mind. Build your character. Become the person your younger self hoped you'd become. Have you ever noticed the guys with the biggest mouths are usually the biggest cowards? And the man that is quiet, calm, and confident, well, he's the guy you need to look out for. Because he's ready to back it up. He is prepared, hard, stoic, confident and tempered. Remember, there are two types of people in this world: trained and untrained. The world has enough spectators. Become someone who's ready for whatever comes next.  I've been asked recently, "Why the hell do you ruck so much?"
Most people spend their lives trying to make exercise easier. They look for shortcuts, hacks, and the newest piece of equipment that promises maximum results with minimum effort. Then there's rucking. You voluntarily throw weight on your back and walk into discomfort. No headphones blasting motivation. No mirrors. No machines counting your reps. Just you, the load, and the voice in your head trying to convince you to quit. That's exactly why it works. Rucking builds legs, lungs, grip, posture, and work capacity. But those are just side effects. The real adaptation happens between your ears. Every mile teaches you that discomfort isn't an emergency. Fatigue isn't failure. And your body is capable of far more than your mind usually allows. The strongest people I know aren't always the biggest or the fastest. They're the ones who keep moving after the novelty wears off. They shoulder the load. They keep putting one foot in front of the other. They become the kind of people who don't panic when life gets heavy—because they've practiced carrying heavy things. That's why I ruck. Not because it's easy. Because life isn't. Become harder to break. Become better at life and the obstacles it throws at us. Become resilient, become tempered, and become dangerous. Pick up the damn weight and start walking. Pick up my eBook Iron Forty. There's everything you need to know to become dangerous again, including extensive chapters on rucking and conditioning.  Why am I doing heavy carries nearly five days per week?
Everyone wants the next "secret" exercise. Well, there is no secret. In fact, one of the best things you can possibly do is as old as time. A necessary component of survival and building strength that is usable in everyday life. Many people are grinding out workouts in the gym or not lifting anything at all. And those who are training are often, always ignoring one of the most brutally effective things they could be doing: weighted carries. Or what is also commonly referred to as a farmer's carry. Pick up something heavy and walk. That's it. Farmer's carries build grip strength, core stability, traps, shoulders, work capacity, and mental toughness—all at the same time. They expose weak links faster than almost any exercise in the gym. They're also one of the most functional movements you can train. Life doesn't care how much you bench. It cares whether you can carry the groceries, move furniture, haul your kid, or keep moving when you're tired. Or maybe, most importantly, be able to react when faced with an extremely difficult emergency situation. If you're over 40, weighted carries are money. They help build the kind of strength that actually shows up outside the gym. My Iron Forty Carry Test (that my clients work toward) Farmer Carry – Bodyweight for 100 yards. Sandbag Carry – 100 lb for 400 meters. Ruck – 3 miles with 30 lb under 45 minutes. If you can hit these benchmarks, you're ahead of 99% of the population. If not, time to get to work. Stop chasing complicated. Grab something heavy. Walk. Repeat. |
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