Don’t you just love it when your workout-loving friend tells you to stay away from donuts? Really, Karen? Who made you the Fitness Tycoon of Donutville? Curb calories, dam sugar like a beaver, and snack hate… sure, they sound like healthy habits, but they might be screwing with your gym life. When your Fitbit is running on overtime, like a marathon-preparatory session, turning your back on these set-in-stone nutrition tips might just have you high-fiving yourself in the mirror.

Numero uno in line for the chop-block is "Avoid Refined Carbs and Added Sugar." It's like a broken record from diet gurus perpetually telling you to pick a fight with refined carbs (looking at you, white bread and pasta). Complex carbs do have their share of glamour, given that fiber is the heart's best friend and weight manager du jour. However, if you’re going the extra mile with your workouts, refined carbs might have your back.

Why? Picture refined carbs as your workout's BFF, helping you stock up on energy faster (kinda like your over-optimistic sport drinks). According to sports nutrition queen Destini Moody, RD, your energy reserves tap out during an exhausting 75-minute workout. Having a pre-match rendezvous with refined carbs or fruit can fuel the furnace that'll keep you going throughout your sweat session.

The second myth that needs busting is "Limit Carbs Altogether." In a world obsessing over cutting carbs like it’s the new black, it's easy to fall into the low-carb diet trap. But hey, workouts and low carb intake are like oil and water. Low-carb diets often act like souped-up Vespas rather than high-fuel sports cars, restraining your metabolism and sucking the life out of your workout mojo.

And now the third one – "Avoid High-Fat, Calorie-Dense Food." Feed calorie-heavy food to physique powerhouse athletes and watch them turn it into pure, golden-grade energy, like reverse alchemists. When you’re blazing through calories during workouts, gracing your salad with an extra sprinkle of avocados, potatoes, and even peanut butter is akin to adding nitrous to your car.

Next up, we've got "Never Eat Between Meals." That tummy rumble you hear every so often is the piper calling for his dues. Starving yourself between meals won't win you any medals! Active individuals need to refuel every three to four hours, emerging victorious against fatigue and hunger.

Fifth is "Don't Eat Before Bed." Kissing goodnight to this myth may end up giving your muscles a helping hand. A pre-bedtime snack can be for your muscles what a lullaby is to a baby - recovery magic. A sip of milk, a spoon of cottage cheese, or yogurt might work, but tread carefully so it doesn't disrupt your sleep.

In the sixth place comes "Reduce Salt Intake." Excess salt - a health hazard, sure, but when your sweat is making the Niagara Falls proud, you might need it again. And if you're sweating like you hit a geyser vein, you may need even more.

The seventh myth is "Eat Only Whole Foods, Not Supplements." Supplement shaming is rampant, but certain concoctions like protein shakes or vitamin D and iron supplements can pack a punch for your performance.

Lastly, the myth of "Plant-Based Milk Is Better Than Cow’s Milk." Vegans, don't throw your tofu at us just yet! For athletes, cow's milk outperforms its plant-based kin. Packed with protein, fat, and carbohydrates, cow’s milk provides a one-stop-shop for vital nutrients. Yes, it’s okay to be on Team Tofu and still partake in endurance events; just make sure your plant-based diet nourishes you right for the sweat ahead.

In the end, let's remember that everyone's fitness journey and diet needs are unique. Understanding what fuels your body best, throwing stigmas out the window and telling Karen to leave your donuts alone is a surefire path to achieving your personal best. More power to you, gym warriors!