Fueling Myths That Are Slowing You Down

There’s a strange paradox in cycling. We have access to more data than ever—power, heart rate, kilojoules, and a dozen other metrics. Yet, when it comes to the most fundamental part of performance—fueling—we’re often bogged down by myths that are as persistent as they are wrong.

Let's cut through the noise. Your body is an incredibly sophisticated system, but it's also a ruthless energy accountant. If you try to cheat it with clever "hacks" or flawed logic, it will always win. Here are the myths you need to ditch to get faster.

Myth 1: You Only Need to Replace the Carbs You Burn

This one sounds logical on the surface. Your power meter says you did 2,000 kJ of work, and you know a certain percentage of that came from carbohydrates. So you just need to eat back that number of carbs, right?

Wrong. Your body doesn't have separate accountants for fats and carbs. It has one master ledger, and it's all about total energy.

Let's use an absurd example to make a point. Imagine a five-hour ride where you burn 3,500 kilojoules. Let's pretend, through some metabolic wizardry, this was all fat. That's roughly 3,500 kcal, which is the equivalent of one full pound of body fat. If you finish that ride and only replace the handful of carbs you used, you've created a one-pound energy deficit in five hours.

Sounds like a weight-loss win, right? Not so fast. A sustainable, performance-friendly rate of weight loss for an average athlete is about half a pound per week. The rate you just achieved was over 66 times faster than that.

Your body's response to this isn't a polite nod of approval for burning fat. It's a full-blown panic attack. It screams, "WE ARE IN A MASSIVE ENERGY CRISIS!" and triggers a cascade of hormonal signals that will make you ravenously hungry, tank your recovery, and impair your performance for days. You don't just feel a little peckish; you feel an insatiable urge to eat everything that isn't nailed down. That's your body balancing its energy books, and it always gets its due.

Myth 2: Burning More Fat on Rides Is the Key to Weight Loss

This myth is the toxic cousin of the first one. The logic is that if you train your body to be a "better fat burner" by, say, doing fasted rides or restricting carbs on the bike, you'll magically melt away your love handles. But as we just established, creating a massive energy deficit in a short window is a terrible idea.

Your adipose tissue (fat) isn't just a passive storage depot for energy. It's a complex endocrine organ that communicates with the rest of your body. One of its key messengers is a hormone called leptin, which tells your brain, "We're full and have plenty of energy."

When you create a huge, acute energy deficit, leptin levels can plummet. Your brain gets the message that a famine has begun. In response, it can ramp up hunger signals (hello, ghrelin), slow your metabolism, and reduce your motivation to move. Ever finished a huge ride under-fueled and found yourself welded to the couch for the rest of the day, feeling cold and grumpy? That's your body actively conserving energy because you sent it a panic signal.

True fat adaptation—the ability to burn fat at higher exercise intensities—is a result of consistent, well-fueled training. It's not something you can "hack" by starving yourself on the bike. The best way to lose weight is to maintain a small, sustainable energy deficit across your entire week, not to wage a five-hour war against your own biology.

Myth 3: Total Energy Needs = BMR + Bike Kilojoules

This might be the most damaging myth for serious athletes. It's the simple formula many apps and online calculators use: Take your Basal Metabolic Rate (BMR)—the energy you need to simply exist—and add the kilojoules from your ride.

This formula is woefully incomplete. It ignores two huge factors:

1. Non-Exercise Activity Thermogenesis (NEAT): This is the energy you burn from everything that isn't formal exercise or sleeping. Walking the dog, fidgeting at your desk, doing chores, playing with your kids—it all adds up.
2. Thermic Effect of Food (TEF): Your body uses energy to digest and absorb the food you eat. It's not a massive number, but it's not zero.

How much does this all matter? A lot. Studies using the gold-standard "doubly labeled water" method to measure total daily energy expenditure in elite athletes have produced staggering results. Research on a female cyclist in the Tour de France found her non-biking energy expenditure was 1.6 to 2.0 times her BMR. That's before adding the thousands of kilojoules she burned on the bike each day.

For most of us who aren't in the Tour, our daily non-exercise energy burn is still likely 1.4 to 1.7 times our BMR, depending on our job and lifestyle. If you rely on the BMR + kJ formula, you could be underestimating your daily needs by 800, 1,000, or even more calories. That's not a fat-loss diet; that's a recipe for low energy availability, poor recovery, and stalled progress.