9 Fitness Myths You Should Stop Following

Fitness advice has a uniquely high noise-to-signal ratio. Some of it is outdated by decades but still in circulation; some of it was never right in the first place but sounded plausible; some of it was right for elite athletes and got translated badly into general-population guidance. The nine items below are the ones most worth retiring — each with a more accurate replacement that current research actually supports.

The framing: most "fitness myths" articles take cheap shots at advice that was never widespread, while leaving the genuinely pervasive bad advice unchallenged. The list below tries to do the opposite. Each item is something you have probably heard from multiple sources, possibly from someone reputable. None of it is malicious. All of it is wrong enough to be worth replacing.

One caveat: "wrong" here means wrong on average, for the general adult population looking to be fitter and healthier. Some of these have specific contexts where they hold up — elite competitive athletes operate by different rules, and some clinical populations have their own constraints. The replacements below are for the much larger group of adults pursuing general health and body composition, not someone training for professional competition or recovering from major surgery.

1. "No pain, no gain"

The most damaging single piece of fitness advice in cultural circulation. The phrase conflates two distinct experiences: discomfort (the burn of effort, the breathlessness of cardio, the fatigue at the end of a hard set) with pain (the sharp signal that tissue is being damaged). The first is necessary and useful; the second is your body telling you something is wrong, and overriding it produces injuries.

The actual rule: train hard enough to be working, but stop or modify anything that produces sharp pain, joint pain, or pain that persists more than 24 hours after the session. The discomfort that comes with genuine effort is fine; the pain that comes with tissue damage is not. Anyone who cannot yet tell the difference needs to work with a qualified coach for a period to learn to read the signals correctly.

Replace with: Train hard, recover smart, listen to your body. Less catchy, considerably more correct.

2. "Cardio is the best way to lose weight"

Cardiovascular exercise is useful for weight loss, but it is not the most efficient single tool, and it is frequently oversold. A 2014 meta-analysis in Progress in Cardiovascular Diseases (Swift et al.) found that isolated aerobic exercise produces only about 0.2 kg per week of weight loss, compared with roughly 1.0 kg per week for caloric restriction alone — diet is roughly five times more effective per week. Furthermore, a 2021 study in Current Biology (Speakman, Pontzer, et al., 1,754 adults measured by doubly labelled water) found energy compensation averaging about 28% when exercise is added — meaning the body claws back roughly a quarter of the calories burned, primarily by moving less the rest of the day. Most cardiovascular exercise also burns fewer calories per session than people estimate.

The actually effective weight-loss approach for most people: a modest calorie deficit driven primarily by dietary change, plus resistance training to preserve muscle mass during the deficit, plus enough cardiovascular activity for general health (150 minutes per week of moderate-intensity activity, per ACSM 2024 Expert Consensus) — but not as the lead lever for fat loss. Diet creates the deficit; resistance training protects the muscle that determines what you look like at the end of the process.

Replace with: Diet is the lead lever for weight loss. Resistance training preserves muscle during a deficit. Cardio supports general health and cardiovascular fitness.

3. "Lifting weights makes women bulky"

One of the most persistent and most thoroughly false claims in fitness advice. Building substantial muscle mass — the "bulky" appearance the warning refers to — requires sustained high-calorie eating, dedicated multi-year training, and (for the dramatic version) hormonal advantages most women do not have. The accidental version is essentially impossible under normal training conditions.

What actually happens when women lift weights with sufficient challenge: improved body composition (more muscle, less fat at the same scale weight), better strength, better bone density — a major long-term health benefit, particularly for postmenopausal women — and a tighter, leaner appearance. The 2026 ACSM position stand on resistance training (its first major update since 2009, reviewing 137 systematic reviews and over 30,000 participants) emphasises that training all major muscle groups at least twice a week is the core driver of benefit, with roughly 10 sets per muscle group per week for hypertrophy. The marketing of low-weight, high-rep "toning" workouts is largely based on this false fear, and does women a disservice.

Replace with: Resistance training is one of the highest-leverage interventions for women's long-term health and body composition. Lift heavy enough to actually challenge the muscles.

4. "You can target fat loss to specific areas (spot reduction)"

The dream of doing crunches to lose belly fat, or tricep extensions to lose arm fat, has been thoroughly disproven and still dominates fitness marketing. A 2022 PRISMA meta-analysis of 13 randomised controlled trials involving 1,158 participants (Ramirez-Campillo et al., Human Movement) found that localised muscle training had no effect on localised fat depots: the pooled effect was Hedges' g = −0.03 (95% CI −0.10 to 0.05, p = 0.508) — statistically indistinguishable from zero. Fat loss is systemic; the body draws from fat stores based on a combination of genetic distribution, hormonal status, and overall energy deficit, not based on which muscle group you are exercising.

The exercises marketed as "burning belly fat" do nothing of the sort. They strengthen the abdominal muscles, which is genuinely useful, but the visibility of those muscles depends almost entirely on overall body-fat percentage, which is determined by overall energy balance. You can perform a thousand crunches a day and not lose a single gram of belly fat if your overall energy balance is even slightly positive.

Replace with: Train muscles to strengthen them. Lose fat through overall energy deficit and consistency. The two are different goals with different methods.

5. "Stretching before a workout prevents injuries"

Specifically, static stretching — holding stretches for 30+ seconds — before exercise. The research has been clear for more than a decade: pre-workout static stretching does not reliably prevent injuries, and it temporarily reduces strength and power output, which is the opposite of what you want before training. The more useful warm-up is dynamic — leg swings, arm circles, walking lunges, light versions of the day's main movements — which actually prepares the body for what is coming by raising tissue temperature, increasing blood flow, and rehearsing movement patterns.

Static stretching has its place, particularly post-workout or in dedicated mobility sessions, where it can help maintain or improve flexibility over time. The "warm-up" name is the clue: you are trying to warm tissues up and rehearse the session's movements ahead, not passively lengthen cold muscles.

Replace with: Dynamic warm-up before training. Static stretching after sessions or in standalone mobility work.

6. "More is always better — train every day, train longer"

The "more is always better" mentality is responsible for more plateaus, injuries, and dropouts than any other single attitude in amateur fitness. Recovery is when the body actually adapts to training; insufficient recovery means insufficient adaptation. Beyond a certain weekly volume, additional training produces diminishing returns at best and overtraining syndrome at worst — with measurable declines in performance, persistent fatigue, and increased injury risk.

For most adults, 3–5 training days per week with deliberate progressive overload and adequate rest produces better long-term results than 6–7 days of grinding. Sleep, nutrition, and rest days are not time wasted — they are when adaptation happens. The 2026 ACSM resistance-training position stand confirms that training all major muscle groups twice weekly with ~10 working sets per muscle group per week is the core volume that produces results; complexity and frequency beyond this add modest incremental benefit for most people, not a step-change improvement.

Replace with: Train hard, recover hard. Quality and consistency over raw quantity. Rest days are training days for the body's adaptive response.

7. "Soreness is the sign of a good workout"

Delayed-onset muscle soreness (DOMS) is essentially a signal of unaccustomed exercise — the body's response to novel mechanical stress, particularly eccentric loading. It happens reliably to beginners, returns whenever you substantially change exercises or increase volume, and largely disappears once the body adapts to the routine. That is the critical point: it is a signal of novelty, not a signal of quality.

What that means in practice: an experienced lifter on a consistent, well-designed programme will often have minimal soreness most of the time and is making real progress. A beginner doing wildly different workouts each session will often be extremely sore while making poor progress, because there is no consistent stimulus to adapt to. Soreness is information about how novel the stimulus is, not about how effective the training is.

Replace with: Progressive overload is the sign of a good programme. Soreness comes and goes; consistent measurable progression is what produces results.

8. "Don't eat carbs if you want to lose weight"

Low-carbohydrate diets work for some people — usually because the carb restriction inadvertently reduces total calorie intake — but they are not metabolically magical, and the underlying claim ("carbs make you fat") is wrong in the simple form most people hear it. Body fat is gained from caloric excess regardless of macronutrient source. Low-fat and low-carb diets produce similar weight loss over a year when calorie intake is matched, as multiple controlled trials have shown. The macronutrient composition matters less than total calorie intake, food quality, and protein adequacy.

For most active people, carbohydrates are useful and arguably necessary — they fuel intense training, support recovery, and improve sleep quality when timed appropriately. The cleaner practical guidance: eat enough protein (1.6–2.2 g per kg of bodyweight for active adults, per ACSM guidelines), get most calories from whole foods, and let the carbohydrate-to-fat split fall where it suits your preference and adherence. The diet you maintain is the one that works.

Replace with: Protein adequacy and whole-food quality matter most. Carbohydrates are not the enemy; calorie excess is. Pick a macronutrient structure you can maintain long term.

9. "You need to do crunches and sit-ups for a strong core"

Crunches and sit-ups train one muscle (the rectus abdominis) in one movement pattern (spinal flexion) — and the repeated spinal flexion under load is increasingly identified as a contributor to lower back problems over time. The functionally relevant core — the integrated system of abdominals, obliques, transverse abdominis, lower back muscles, glutes, and diaphragm — is trained much more effectively by anti-extension, anti-rotation, and anti-lateral-flexion movements: planks, dead bugs, bird dogs, Pallof presses, suitcase carries, and rollout variations.

The shift in evidence-based core training over the past 15 years has been from movement-based work (many crunches) to stability-based work (resisting movement under load). The latter trains the core as it actually works in real life — keeping the spine stable while other things happen around it — rather than isolating a single superficial muscle in a movement pattern most activities don't replicate. The myth that "six-pack exercises" are core training has persisted partly because the rectus abdominis is the visible layer, even though it is only one component of a well-functioning core.

Replace with: Planks, dead bugs, bird dogs, anti-rotation work, and loaded carries. Reduce or skip high-volume crunches, particularly if you have any history of lower back pain.

Where this leaves you

The nine items above span a representative slice of bad fitness advice in circulation. The common thread is that each sounds plausible until you look at the evidence, and each has a more accurate replacement that the research now supports clearly. The cost of believing them is not catastrophic, but it adds up over years: wasted training time, slower progress, occasional avoidable injuries, and stalled results that get blamed on personal failure rather than on the bad advice that created the conditions for the plateau.

The deeper lesson is to be sceptical of fitness advice that is catchy, absolute, or surprisingly simple. Real exercise science is full of "it depends," "for most people but with these exceptions," and "the evidence has moved on since this got popular." The advice that travels widely tends to be the simplified version that has lost most of its accuracy in transmission. When in doubt, look up the actual research, consult a qualified coach or physiotherapist, and weight your sources toward people with formal training in exercise physiology rather than those with large social-media followings.

For more grounded fitness perspectives, the pieces on why running is genuinely good for your health and starting a consistent morning exercise habit approach the practical side from a similar evidence-anchored angle. For the dietary side that intersects with most of these myths, 29 science-backed dieting tricks covers the nutritional evidence base that complements good training.