No matter how much fitness and training continues to evolve, some myths refuse to go away, no matter how often they’ve already been debunked. Jeff Cavaliere finally hopes to destroy each fitness fallacy one fact at a time.
Cavaliere—physical therapist, strength coach, and founder of ATHLEAN-X—has built a massive social media following by providing straightforward solutions to the confusing—and oftentimes dishonest—world of fitness advice. With years of working alongside elite athletes and weekend warriors, Cavaliere addressed the still confusing fitness myths that remain on social media and in the weightroom. He developed his myth-busting assessments as a public service: to separate fact, fiction, and half-truths, while teaching people why the science matters for real-world results.
The Athlean-X’s approach is rooted in both evidence and experience as he explains on his YouTube channel. “Some of these are just total BS. Some are actually half true, and others are totally legit. But the key is knowing which is which—that changes everything,” Cavaliere says. By examining the simple logic behind popular yet questionable claims, Cavaliere explains why each belief persists, what research really shows, and how practical application can be different from theory for different bodies.
Below are some of Jeff Cavaliere’s most common fitness myths—why they are often misunderstood, and what you need to know so you don’t fall victim when you’re trying to add muscle and strength to your frame. Jeff Cavaliere’s myth assessments aren’t just about busting old beliefs—they’re about helping you understand nuance and apply science to your real-life fitness goals. By questioning commonly held assumptions, you can work out safer, smarter, and stay motivated for the long haul.
Jeff Cavaliere’s Top Fitness Myths
1. You Can’t Build Muscle and Burn Fat at the Same Time
- Myth Level: FALSE
- What’s True: While it’s harder, especially for advanced lifters, you can build muscle and burn fat simultaneously by keeping caloric deficits moderate and protein intake high. It requires patience and smart strategy, not aggressive dieting.
- What You Could Do: Cavaliere challenges the notion that muscle building and fat burning have to be mutually exclusive. He says the key is to be able to balance calories and high protein. “If you’re willing to take just a little bit more time…you absolutely can build muscle and burn fat at the same time,” he says.
2. Carbs Make You Fat
- Myth Level: HALF-TRUE
- What’s True: Carbs themselves don’t inherently cause fat gain; it’s excessive calories overall. Carbs can cause short-term weight gain from water retention, but are not the enemy of a lean physique.
- What You Could Do: Contrary to popular belief, Cavaliere asserts that carbohydrates themselves are not the culprits for weight gain, but instead your caloric intake. “A surplus of calories can make you fat,” he explains.
3. You Need a Variety of Exercises to Build Muscle
- Myth Level: TRUE (sort of)
- What’s True: A handful of core compound lifts (think squat, bench, deadlift, row, curls, dips/overhead press) can build a solid body if performed with progression.
- What You Could Do: Cavaliere stresses that variety isn’t essential for muscle development. Different exercises may keep workouts interesting and can help with weak points, but the basics—including deadlifts and squats—are still the tried and true kings of training. “When you have the right exercises…you can actually build a lot of muscle,”
4. Fasted Cardio Burns More Fat
- Myth Level: PARTLY TRUE
- What’s True: You burn more fat during fasted cardio, but total daily calorie balance is what determines fat loss. The best method depends on what you can adhere to consistently.
- What You Could Do: Don’t stress fasted cardio unless it fits your routine—Cavaliere says to focus on long-term consistency. While fasted cardio may burn a higher percentage of fat, Cavaliere clarifies that it does not equate to greater overall fat loss. “The only way we lose body fat is by being in a caloric deficit,” he says.
5. There Are No Bad Exercises
- Myth Level: VERY FALSE
- What’s True: Some movements, like upright rows and unsupported one-arm rows, pose unnecessary risks. Exercise selection should protect your joints, not just build muscle.
- What You Could Do: Cavaliere firmly disagrees with this myth, stating, “There are bad exercises,” particularly those that increase the risk of injury. He points out the dangers of movements like the upright row, which can lead to shoulder impingement. Instead, prioritize movements that are safe and effective for your body structure and injury history.
6. Spot Reducing Belly Fat with Ab Workouts
- Myth Level: FALSE
- What’s True: Training abs won’t burn belly fat. Fat loss is systemic, and diet is the true game-changer.
- What You Could Do: Cavaliere suggests focusing on nutrition and total-body workouts. Don’t neglect ab training, you still need to strengthen those muscles, just don’t rely on them as a fat burner. “The only way to lose fat is through a caloric deficit,” he explains.
7. Women Get Bulky from Lifting Weights
- Myth Level: FALSE
- What’s True: Because women have much less testosterone, there is little to no chance that they will be able to “bulk up” from resistance training. Instead, weight training is the key to a healthy, toned physique.
- What You Could Do: Women should embrace strength training for better strength, health, and overall confidence, Cavaliere says. “Women don’t have the testosterone levels required to gain muscle mass like men do.”
8. Sweat Indicates Workout Effectiveness
- Myth Level: FALSE
- What’s True: Sweat is your body’s way of cooling down, not a measure of effort or calorie burn.
- What You Could Do: Don’t judge workouts by the puddle—judge by performance and progression. Cavaliere debunks the myth that sweating is directly linked to calorie burn. “Sweat production is merely a way for your body to cool down,” he says.
9. The Anabolic Window is 30 Minutes
- Myth Level: HALF-TRUE
- What’s True: Post-workout protein is helpful, he says, especially if you haven’t eaten much before training, but the critical window is more like several hours, not a half hour
- What You Could Do: Cavaliere challenges the belief in a strict 30-minute anabolic window post-workout for optimal protein intake. “While nutrient timing can be important, you have a larger window to consume your protein;. indicating that the focus should be more on daily protein intake rather than a specific time frame.”
10. Knees Over Toes Is Bad in a Squat
- Myth Level: FALSE
- What’s True: Healthy squats often require your knees to travel beyond your toes, which helps proper biomechanics. Avoiding it can cause other problems.
- Why You Should Care: Learn sound mechanics instead of simply following outdated rules, Cavaliere says. Additionally, he points out that when performed correctly, squatting with the knees over the toes does not inherently increase the risk of injury. Instead, factors such as poor form, excessive weight, and lack of proper warm-up are much more likely to lead to injury. “The knees are meant to be able to move forward in a squat. As long as the heels are down and the movement is controlled, this can be completely safe.” Instead, focus on proper squatting mechanics, strength training, and flexibility should be prioritized over strict adherence to outdated guidelines.