Nutrition for Sweet Spot

Sweet spot is that sub-threshold Zone 3/4 place you described so well: “95–98% of FTP… that sweet spot to where your not teetering over threshold but slightly below.” It’s the zone where you glance at the Zwift workout graph and “see a mix of green and yellow”—and you feel that blend in your body too: controlled pressure, steady breathing, legs working hard but not unraveling. It’s not a dramatic, all-out effort. It’s the kind of effort you can come back to again and again, and that’s exactly why it builds such a durable engine.

What makes sweet spot so effective is also what makes it so revealing: the energy demands are real. You can’t “mindset” your way around physiology. At this intensity, your muscles are rebuilding ATP (your working energy currency) rapidly and continuously, and the closer you are to threshold, the more your body leans on carbohydrate (glycogen + blood glucose) to keep that ATP production smooth. This is why sweet spot blocks are so powerful pre-season—“a crucial step for getting a bigger and stronger engine”—but it’s also why fueling becomes non-negotiable. Engines don’t get bigger on inspiration alone. They get bigger when the workload is supported and repeatable.

That’s where the nutrition conversation gets messy online, because lately a very specific narrative has been making the rounds—usually chopped into a 15-second Instagram reel with a scary caption. You mentioned it directly: a late 2025 review in Endocrine Reviews by Dr. Andrew Koutnik and colleagues, which has been framed as “high-carb loading might hinder performance” because it suppresses fat oxidation, and that athletes should prioritize metabolic flexibility and fueling based on brain energy needs rather than maximum glycogen storage. The paper does argue strongly around substrate shifting and blood glucose protection. But the problem isn’t that the paper exists—the problem is how quickly it gets turned into “carbs are the enemy,” which is a completely different claim than thoughtful performance fueling.

And this is where your reaction is important, because you’re not reacting like someone trapped in diet culture. You’re reacting like a coach who’s watched athletes train, race, adapt, and burn out.

“i want to debunk this ephasizing that the researchers were all men who highlighted the keto diet. there was a ton of bias which tends to be the case for many article and when i saw this on instagram, it made me sad because we need to look at an athlete in a different way.”

That sadness makes sense, because diet-trend messaging often treats the athlete’s body like it’s the same as a sedentary person’s body trying to cut calories. It forgets that training is a biological demand, not a moral choice. It forgets that “metabolic flexibility” isn’t a diet label—it’s the body’s ability to use the right fuel at the right time to meet the work.

If you zoom out and look at what’s actually happening at the highest levels of the sport, your next line becomes the clearest reality check:

“look at all the tour riders and pros... they kee going up in carbs every year and they keep getting faster and faster.”

That trend is hard to ignore. Elite fueling strategies have generally shifted toward higher carbohydrate intake during hard, long racing because it supports higher sustained outputs and more frequent surges. And that’s not because pros are “addicted to carbs.” It’s because watts cost energy, and carbs are a powerful way to pay that bill when intensity is high.

Here’s the missing link that ties all of this together—and it’s exactly what you asked to make clear: carb/glycogen use correlates with energy demand from power output. As power rises, your muscles need ATP at a faster rate. Carbohydrates can be converted into usable energy at a higher rate than fat, and they support high-intensity aerobic work more effectively because they’re more oxygen-efficient per unit of power. So when you’re living in sweet spot—especially the high end you’re talking about—carbs aren’t some trendy preference. They’re often the most practical tool for sustaining that intensity cleanly.

But none of that means athletes should mindlessly shovel carbs 24/7, and this is where your most important point belongs—because it’s the real “debunk,” and it’s the nuance social media skips:

“now if your doing endurance and shoving 100g er hour of carbs down. thats werll over the energy demands that you are putting out and thats when it becomes a problem.”

That’s the truth. The issue usually isn’t “carbs.” It’s mismatch—intake that doesn’t match the session. If you’re truly riding low-intensity endurance and you’re forcing 100g/hr, you can run into gut overload, sloshing, bloating, appetite disruption later, and an overall sense that fueling “doesn’t work.” But the takeaway isn’t to fear carbs; the takeaway is to fuel with intention. Match the input to the output.

And that’s exactly why your sweet spot recommendations land so well—they’re not extreme, they’re intelligent, and they respect the job the body is doing in that zone.

“as i would reccomend 50-60g carbs per hour of efforts that focus on sweet spot.. sloser to threshold, it goes to 70-80g.”

That’s a strong framework because it scales with physiology. Sweet spot needs enough carbohydrate to protect power output and reduce the drift into “survival mode,” while efforts closer to threshold increase the carbohydrate contribution and make stable blood glucose even more important. In other words, you’re not chasing a trendy number—you’re supporting the intensity so the workout stays repeatable, and the block stays productive.

Still, even those ranges aren’t one-size-fits-all, and you made the most athlete-aware adjustment of all:

“now if your a tiny human outoutting smaller watts at sweet spot then you maight need slightly less or if you are a bigger ridser outputting more watts, you will need more energy to hewlp produve that power.”

This is the part that instantly upgrades someone’s understanding. Two riders can both be riding “sweet spot,” but one might be holding 160W and the other 280W. That’s a different energy cost per hour. Bigger output usually needs bigger input—not because anyone is “doing it wrong,” but because watts are energy.

And once you understand that, you can finally step out of the cultural whiplash that keeps trying to turn nutrition into a villain story. You said it clearly:

“society has made us afrais of carbs but if you remeber in the 90s they made of fear faat and added sugar to a bunch of things.”

Exactly. The pendulum swings: fear fat, fear carbs, fear something else next year. But performance doesn’t live on a pendulum. Performance lives in the middle: what supports your training and helps you recover so you can show up again.

That’s why athletes are different from the “diet trend” target audience. Diet trends are usually built for appetite control, weight loss through restriction, and simplified rules for general population behavior. Training is different. Training is a planned stress that requires planned support. Your goal isn’t to eat like an influencer—it’s to adapt like an athlete. And that’s why your guiding line matters:

“i want you to find what works for you. dont overdo it and dont underdo it”

That’s the whole coaching philosophy in one sentence.

And honestly, this is also why Zwift is such a gift for learning fueling—because it turns your training into a controlled lab where you can connect what you put in with what you get out. You captured that perfectly, and it deserves to be part of the message, not an afterthought:

“and thats why i like Zwift becasue yes i encourage you to test these. no nutrition, mid nution, right on, and over. not every day but occasional trainign days you want to test this out and see what your body does and get to see the difference of all the levels of energy imput with your outut.”

That is how athletes build confidence. Not by arguing online, but by experimenting intentionally. On occasional training days—never when it would sabotage key sessions—you can test low fuel, moderate fuel, “right on,” and over-fueled, and then notice what changes: power stability, HR drift, perceived effort, mood, gut comfort, and recovery the next day. Over time, you build your own map. You learn where your body thrives and where it complains. You stop guessing.

And when you stop guessing, you stop being afraid—of carbs, of trends, of headlines, of what someone else claims is “optimal.” You become the athlete who fuels for the work in front of you, respects the body you have, and keeps coming back to sweet spot because it works—not just on paper, but in real life.