Ten of the most common health myths women believe — from “always finish your antibiotics” to “eat less to lose weight” — are either outdated, oversimplified, or flat-out wrong. Doctors have been updating the guidance on all of them, and for women navigating fat loss, energy, and body composition after 40, believing the wrong ones can keep you stuck for years.
My client Katie came to me after a full year working with a nutritionist through her insurance. She had Hashimoto’s, perimenopause, adrenal fatigue, and almost no progesterone left. She was a former personal trainer. She knew more about fitness than most people ever will, and she was still gaining weight. She was eating at or below 1,200 calories a day, running on fumes, and wondering what was wrong with her body.
Nothing was wrong with her body. What she had been handed — from doctors, from dietitians, from fitness culture in general — was a collection of myths dressed up as medical advice. She found the FASTer Way, increased her calories strategically, and within 6 weeks her energy had skyrocketed and her afternoon crashes were completely gone.
Katie’s story isn’t unusual. It’s the story I hear from women every single round, and almost all of them have one thing in common: they’ve been following advice that science has either updated or abandoned entirely. So let’s go through ten of the biggest ones.
Myth #1: You Should Always Finish Your Full Course of Antibiotics
This one has been drilled into all of us since childhood, so it feels almost wrong to say it out loud: the “always finish your antibiotics” rule is no longer supported by the evidence. Researchers at Oxford University, led by infectious disease professor Tim Peto, published a landmark analysis finding that the idea patients must finish the full course to prevent antibiotic resistance is, in their own words, “a modern myth, deeply embedded in our culture but based on no sound scientific evidence.” For common bacterial infections, stopping early when symptoms resolve does not appear to increase the risk of resistance. In some cases, finishing an unnecessarily long course may do more harm than good. This doesn’t mean you should stop antibiotics on your own without guidance — always check with your doctor. But the next time you feel better at day five of a ten-day course and wonder whether you still need the rest, that’s worth a conversation.
Myth #2: Eating Less Is the Key to Fat Loss
This is the one that costs women the most time, energy, and peace of mind. The story goes: eat in a deficit, lose fat, done. And while a calorie deficit does matter, the idea that eating as little as possible is the fastest route to fat loss is directly contradicted by what happens in the body when you chronically undereat.
When you drop calories too low for too long, your body treats it as a food shortage and adapts accordingly — slowing metabolic rate, increasing hunger hormones, and conserving energy rather than burning it. Research has shown that metabolic adaptation during aggressive calorie restriction can reduce your metabolic rate by 10 to 25%. A follow-up study of contestants from The Biggest Loser found that six years after the show, their metabolisms had slowed dramatically and most had regained the weight, despite continuing to eat less than the average person.
Katie knew all of this intellectually as a personal trainer. What she hadn’t experienced was eating MORE — strategically, with macro targets and carb cycling — and watching her body finally release the weight it had been holding onto for years. Eating as much as possible while being intentional is the goal, not eating as little as you can tolerate.
The goal is not to eat as little as possible. It’s to eat as much as possible while being strategic about what, when, and how.
Myth #3: Cardio Is the Best Way to Lose Fat
Cardio gets all the credit, and strength training gets treated like a nice bonus. The research tells a different story. Resistance training builds muscle mass, and muscle tissue burns more calories at rest than fat tissue does — meaning every pound of muscle you add increases your baseline metabolic rate permanently. Strength training also creates what’s called an EPOC effect (Excess Post-Exercise Oxygen Consumption), where your body continues burning calories at an elevated rate for hours after you finish the workout. A steady-state cardio session doesn’t do that to the same degree.
My client Diane had been working out five to six days a week for nine years — strength, HIIT, and cardio — and had zero visible muscle definition to show for it. No definition, despite nearly a decade of consistent effort. What she was missing wasn’t more movement. It was the nutrition strategy to support the movement she was already doing. When she added macro tracking and carb cycling to her existing routine, she lost nine total inches and cried at her week six progress photos. The exercise was always right. The fuel was the missing piece.
Myth #4: Fat Makes You Fat
The low-fat era of the 1980s and 1990s did tremendous damage to how women understand nutrition, and we’re still cleaning it up. The belief that eating fat causes body fat is not supported by current research. The landmark PREDIMED trial, published in the New England Journal of Medicine in 2018, found that a Mediterranean diet rich in healthy fats reduced cardiovascular events more effectively than a low-fat diet. And the 2015 Dietary Guidelines removed the longstanding recommendation to limit dietary cholesterol entirely, after decades of research showed it has minimal impact for most people.
What dietary fat does do: it supports hormonal function (including the estrogen and progesterone your body is already working to regulate in perimenopause), slows the absorption of carbohydrates to keep blood sugar stable, and keeps you satiated for longer. Removing fat from your diet doesn’t make you leaner. It often just makes you hungrier, hormonally disrupted, and reaching for the low-fat crackers that replaced it with sugar anyway.
Myth #5: Detox Cleanses Help Your Body “Reset”
Juice cleanses, detox teas, 10-day resets — the wellness industry has built an enormous business on the idea that your body needs periodic outside help to “flush toxins.” It doesn’t. Your liver and kidneys detoxify your body continuously, and no cleanse or supplement product has been shown to meaningfully enhance that process. The British Dietetic Association has categorically dismissed detox diets as pseudoscience.
What most cleanses actually produce is temporary water loss and calorie restriction, not fat loss. And for women in perimenopause specifically, highly restrictive low-calorie approaches can disrupt hormonal balance further and cause the exact energy crashes and mood swings you’re trying to get rid of. If you want to support your body’s natural detoxification, the evidence-backed approach is simple: eat enough protein (your liver needs amino acids to function), drink enough water, prioritize sleep, and reduce the processed foods that actually burden the system. That’s the reset. No cayenne lemonade required.
Myth #6: Carbs Are the Enemy
The pendulum swung hard from low-fat to low-carb, and a lot of women got caught in the middle convinced that carbohydrates were the root of all their body composition problems. The 2018 DIETFITS trial compared a healthy higher-carb diet (48% of calories from carbs) against a healthy lower-carb diet (30% of calories from carbs) in overweight adults, and found no significant difference in weight loss at 12 months. What the research consistently shows is that total caloric context and food quality matter more than carbohydrate content alone.
Carbohydrates are also your body’s preferred fuel source for exercise, particularly during higher-intensity workouts. Carb cycling — strategically adjusting your carbohydrate intake based on your activity level — is a tool that works precisely because it uses carbs intentionally, not because it eliminates them. My client Jessica had been stuck on 1,200 calories a day with no carbs worth mentioning, spending $120 a month on boot camps, and not losing a single pound. She started the FASTer Way, increased her calories well above what she had been eating, applied carb cycling, and lost 10 pounds and 8.25 inches in six weeks on 30-minute workouts. The carbs weren’t the problem. The strategy was.
Myth #7: You Need to Eat Every 2-3 Hours to Keep Your Metabolism “Stoked”
The idea that frequent small meals “stoke your metabolic fire” was repeated so often in fitness culture that it became accepted fact, despite a notable lack of clinical evidence to support it. What research actually shows is that total daily caloric intake and food quality matter far more than meal frequency. The thermic effect of food — the calories your body burns digesting what you eat — accounts for roughly 8 to 10% of total daily energy expenditure regardless of whether you eat two meals or eight.
A 2019 review published in the New England Journal of Medicine found that time-restricted eating and intermittent fasting can improve blood sugar regulation, reduce inflammation, and support weight management in many people — suggesting that fewer, larger meals eaten during the body’s natural active hours may actually be metabolically favorable. Your body doesn’t need constant feeding to function well. What it needs is the right fuel at the right times.
Myth #8: The Scale Is the Best Measure of Progress
The scale measures one thing: total body weight, which includes muscle, fat, water, food in transit, inflammation, and hormonal fluctuation. It does not measure body composition, which is what most women are actually trying to change. Gaining muscle while losing fat — which is the whole point of pairing strength training with strategic nutrition — can look like stalled progress or even weight gain on a scale, while visibly transforming your body.
My client Emily had been in VIP for about five months when she went back to work after a summer break. She was actually up a pound or two on the scale the day before and was feeling disappointed. Then six different coworkers independently asked how much weight she had lost on her first day back. “The crazy thing is that I’ve only lost about 7 or 8 pounds,” she said, “and I was actually kinda bummed yesterday because I was up a pound or 2.” Body recomposition shows up in photos, in how clothes fit, and in what people notice when they haven’t seen you in a while. The scale is one data point, not the whole picture.
Myth #9: Running Causes Knee Damage
This one has scared women away from one of the most accessible forms of movement available to them. The fear is that repetitive impact degrades cartilage and causes or accelerates arthritis. The research doesn’t support it. Cartilage actually needs the compression and decompression that comes from impact activity to stay healthy and receive nutrients — it functions more like a sponge than a fragile structure. Multiple studies have found that long-distance runners don’t show higher rates of arthritis than sedentary populations, and some research suggests runners have healthier joint cartilage overall. The factors that actually contribute to arthritis are genetics, previous injury, obesity, and chronic inactivity. For most women, the bigger risk to their joints is not running — it’s not moving enough.
Myth #10: If Your Labs Are Normal, Everything Is Fine
“Your labs are normal” might be the sentence that has sent more women home feeling dismissed than almost any other phrase in medicine. Standard lab ranges are designed for the general population, including people at both ends of the health spectrum, and they don’t always reflect what optimal looks like for an individual woman at a specific hormonal stage of her life. Thyroid panels, for example, often only measure TSH when a woman might benefit from a full panel including free T3, free T4, and thyroid antibodies. Hormone panels may show values in the “normal range” while a woman’s estrogen, progesterone, and testosterone are all at the lowest end of that range simultaneously.
If you feel terrible despite a clean lab report — the exhaustion that sleep doesn’t fix, the brain fog, the belly that won’t budge despite doing everything right — that is meaningful data. It is not evidence that nothing is wrong. It’s worth pushing for a more complete picture, working with a functional medicine doctor or hormone specialist, and understanding that how your body feels is a legitimate measure of how it’s functioning.
Ready to Build a Strategy That Works With Your Body, Not Against It?
The 6-Week New Client Experience gives you the macro targets, carb cycling protocol, 30-minute workouts, and coaching to replace the myths with a plan your body can actually respond to. My client Katy tracked her body composition via DEXA scan over 3.5 years — losing 14 pounds of fat while gaining muscle, with strangers on airplanes stopping to ask about her arms. That’s what happens when you stop fighting your body and start fueling it.
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