Ranked by evidence
Training myths, checked against the evidence
What people repeat in the gym, checked against controlled studies. Pages say plainly when a belief does not hold and what to do instead.
- Cardio before weights ruins your gains (exercise order matters) Moderate evidence
This one is partly true.
- Exercise alone is enough to lose weight Moderate evidence
Partly true.
- Calories don't matter, only food quality or hormones do Limited evidence
Calories matter: in tightly controlled feeding studies, eating more than you burn causes weight gain whatever the macronutrient mix, and isocaloric swaps of carbohydrate for fat barely change fat loss.
- Cardio kills your gains Limited evidence
Doing cardio alongside lifting does not, in general, cost you muscle or maximal strength.
- Cheat meals boost your metabolism Limited evidence
A big meal or a few days of overeating nudges energy expenditure and leptin up slightly, but the extra calories burned are far smaller than the extra calories eaten, so a cheat meal does not 'reset' metabolism or speed fat loss.
- Deadlifts are bad for your back Limited evidence
The evidence does not support the idea that deadlifting is inherently harmful to the back.
- Deep squats (below parallel) are bad for your knees Limited evidence
For healthy knees there is no good evidence that squatting deep causes injury, and deep squats build more lower-body muscle than shallow ones.
- Detox diets and juice cleanses flush out toxins and fat Limited evidence
There is no good evidence that detox diets remove toxins or fat.
- Eat every 3 hours to boost your metabolism Limited evidence
Eating small meals every 3 hours does not stoke your metabolism or speed up fat loss.
- Eating carbs at night makes you fat Limited evidence
For weight, what counts is total intake across the day, not the clock.
- Eating fat makes you fat Limited evidence
Dietary fat is not stored as body fat in some special way: at equal calories, low-fat and higher-fat diets lead to similar weight loss in long trials.
Metabolic adaptation is real: when you lose weight, your resting metabolism drops a bit more than the lost tissue explains.
- High reps with light weights tone, heavy weights bulk Limited evidence
There is no special "toning" rep range.
- Lactic acid causes next-day muscle soreness Limited evidence
Lactate does not cause the soreness you feel a day or two after training.
- Lifting weights makes women bulky Limited evidence
Women build muscle at about the same relative rate as men, but from a smaller starting point, so absolute gains are modest and slow.
- Lifting weights stunts children's growth Limited evidence
There is no evidence that properly supervised resistance training stunts growth in children or teenagers.
- Muscle confusion (constantly change exercises to keep growing) Limited evidence
Muscles do not need to be "confused" to grow; they need a progressively harder stimulus.
- Muscle turns into fat when you stop training Limited evidence
Muscle cannot turn into fat: they are different tissues, and one does not convert into the other.
- No pain, no gain (soreness means the workout worked) Limited evidence
Muscle soreness mostly reflects how unaccustomed a workout was, not how much muscle it will build.
No food melts body fat.
- Spot reduction (crunches burn belly fat, leg work burns thigh fat) Limited evidence
Training a body part does not preferentially burn the fat on top of it.
- Stretching before exercise prevents injuries Limited evidence
Stretching before training does not meaningfully reduce injury risk.
- Sweating more means burning more fat Limited evidence
Sweat is water and electrolytes, not fat.
- The anabolic window (eat protein within 30 minutes of training) Limited evidence
The idea that you must get protein in within 30-60 minutes after lifting or lose your gains does not hold up.
- You can't build muscle after 50 Limited evidence
Adults over 50 build both muscle and strength with resistance training, even into their 90s.
- You must stay in the fat-burning zone to lose fat Limited evidence
It is true that the share of energy coming from fat is highest at moderate intensities, but that does not decide how much body fat you lose.
- You should train abs every day Limited evidence
Daily ab training will not uncover a six-pack, and there is no evidence that abdominal muscles need daily work to grow.
- Your body can only use 20-30 g of protein per meal Limited evidence
The idea that anything above 20-30 g of protein per meal is wasted is wrong.