Health Education · Myth Busting

10 Common Health Myths Debunked — What Science Actually Says

Reem Aslam · Final Year MBBS · UHS Pakistan · Evidence-Based

We have all grown up believing certain health "facts" — passed down by parents, spread on social media, or repeated so often they feel true. As a final-year MBBS student, I want to set the record straight on 10 of the most common health myths — using actual science, not opinions.

Some of these will surprise you. Some might even make you a little angry. But every single one is backed by peer-reviewed research and expert medical opinion. Let us get into it.

The 10 Health Myths You Need to Stop Believing

1

You Need to Drink 8 Glasses of Water Every Day

❌ False

The Myth

Everyone must drink exactly 8 glasses (64 oz) of water daily for good health.

The Fact

Water needs vary by person, body size, climate, activity level, and diet.

The "8 glasses a day" rule originated from a 1945 recommendation that was widely misquoted — the original actually stated that most fluid needs are met through food we eat. Subsequent studies have confirmed there is no universal evidence behind the 8x8 rule. Water needs vary significantly between individuals. The best indicator is your urine — pale yellow means adequately hydrated. Dark yellow means drink more. Clear means you are likely over-hydrating. Fluid also comes from fruits, vegetables, soups, and other beverages.

📚 UCHealth · BMJ · Medical News Today

2

Cold Weather Causes Colds and Flu

❌ False

The Myth

Going out in cold weather without a coat will make you catch a cold.

The Fact

Colds and flu are caused by viruses — not by temperature or cold air.

This is one of the oldest and most persistent health myths. Only a virus or bacteria can cause a cold — not the weather. Cold weather does not cause illness. What cold weather does do is drive people indoors where viruses spread more easily in enclosed spaces. One study even found that healthy men who spent hours in near-freezing temperatures actually showed an increase in virus-fighting immune activity. So being cold does not make you sick — being near infected people does.

📚 NewYork Presbyterian · Commonwealth Care Alliance

3

Eggs Are Bad for Your Heart

❌ False

The Myth

Eggs raise cholesterol and increase heart disease risk — they should be avoided.

The Fact

Eating up to 2 eggs daily has neutral or slightly beneficial effects on heart health for most people.

The egg-cholesterol myth originated from mid-20th century research that has since been substantially revised. Modern evidence shows that eating even two eggs daily is safe and has either neutral or slightly beneficial effects on heart disease risk factors. Eggs are one of nature's most nutritious foods — rich in high-quality protein, essential vitamins, healthy fats, and choline which is critical for brain health. The real heart disease risk comes from trans fats, processed foods, and excess sugar — not from eggs.

📚 Medical News Today · Scripps Health · Commonwealth Care Alliance

4

You Need to Sweat Out a Fever

❌ False

The Myth

Wrap up warmly and sweat it out — this will cure your fever faster.

The Fact

Overheating during a fever can be dangerous and worsen dehydration.

A fever is your immune system's natural response to infection — it raises body temperature to create an environment hostile to pathogens. Wrapping up to "sweat it out" can actually raise temperature dangerously and increase fluid loss through sweating, worsening dehydration. What actually helps: staying hydrated, resting, and taking paracetamol or ibuprofen if the fever is causing significant discomfort. Seek medical attention for fevers above 39.4°C (103°F) in adults or any fever in infants under 3 months.

📚 NHS · Mayo Clinic

5

All Fats Are Bad for You

❌ False

The Myth

Fat makes you fat and causes heart disease — a low fat diet is always healthier.

The Fact

Healthy fats are essential for brain health, hormone production, and absorbing fat-soluble vitamins.

Not all fats are created equal. Unsaturated fats — found in olive oil, avocados, nuts, and fatty fish — are essential nutrients that support heart health, brain function, and the absorption of Vitamins A, D, E, and K. Saturated and trans fats — found in processed foods, fried foods, and margarine — are the fats that genuinely increase cardiovascular risk. A low-fat diet often simply replaces fat with sugar and refined carbohydrates — which research now shows is equally or more harmful. The 2020–2025 Dietary Guidelines confirm that healthy fats must be part of a balanced diet.

📚 NIDDK · Scripps Health · EUFIC 2025

6

You Only Use 10% of Your Brain

❌ False

The Myth

Humans only use 10% of their brain — there is 90% untapped potential.

The Fact

Brain imaging shows virtually all brain regions are active — we use essentially all of our brain.

This myth has been popularised by self-help books and Hollywood films for decades. Modern neuroimaging — including fMRI and PET scans — consistently shows that virtually all areas of the brain have a function and are active at various times. While not every neuron fires simultaneously (that would be a seizure), there is no dormant 90% waiting to be unlocked. The origin of this myth is unclear — possibly misattributed to Einstein — but it has no scientific basis whatsoever.

📚 Valleywise Health · neuroscience research

7

Carbohydrates Make You Fat

❌ False

The Myth

Carbs are the enemy — cutting them out is the key to weight loss and health.

The Fact

Weight gain is caused by excess calories — from any sourc