Hormones are often misunderstood, with many myths circulating about their effects on the body. Experts in endocrinology have debunked several common misconceptions, revealing the true nature of hormones like cortisol, testosterone, melatonin, and more.
Puberty Hormones First Get Produced During Adolescence: False
The main puberty hormones—oestrogen and progesterone for girls, testosterone for boys—are active much earlier than adolescence. According to Dr Sasha Howard, clinical reader and honorary consultant in paediatric endocrinology at Queen Mary, University of London and Barts Health NHS Trust, these hormones are active in the womb during foetal development and during infancy in a phase called mini-puberty. This vital period occurs from two to six months of age, when reproductive hormones stimulate the testicles in boys and ovaries in girls, priming these organs for fertility in adult life. Dr Howard notes that a three-month-old baby boy has blood testosterone levels as high as an adult man. During mini-puberty, testicles double in size and boys often have spontaneous erections. In boys, mini-puberty usually completes by six months, but in girls, activity may tail off until between one and two years old. The myth of a testosterone surge in four-year-old boys, often used to explain challenging behaviour, has no evidence; Dr Howard states that between two and 10 years old, reproductive hormone activity is very quiet.
Hormones Are Just a Female Issue: False
Dr Saira Hameed, consultant endocrinologist at Imperial College Healthcare NHS Trust and author of Signals: The Inside Story of Our Hormones, emphasises that hormones affect men and women equally. While women experience periods and menopause, both sexes have the same hormones—women have testosterone and oestrogen, and men have testosterone and oestrogen. The main difference is that men have higher levels of testosterone and women have higher levels of oestrogen. Dr Hameed explains that tests for thyroid function, cortisol, insulin, and blood sugar show no gender differences; aside from fertility, hormones are not gender-specific.
Taking Testosterone Makes You Aggressive: Mostly False
Dr Channa Jayasena, professor of reproductive endocrinology at Imperial College London and consultant in the NHS and private sector, clarifies that testosterone should only be given to men with insufficient levels. In such cases, it is incredibly safe and does not cause aggression; it can improve mood and quality of life. Problems arise when taken without medical guidance, such as men using anabolic steroids to build muscle mass. At very high doses—hundreds to thousands times the required amount—testosterone affects the limbic system, which processes emotions and fear, potentially triggering aggression.
Cortisol Is a 'Bad' Hormone: False
Cortisol, the body's main stress hormone, rises in stressful situations like important meetings or arguments. Dr Hameed describes this as the "cortisol edge," sharpening thinking and alertness, which can be helpful short-term. However, chronic stress leading to persistently high cortisol levels should be addressed by alleviating stress—through spending time with loved ones, exercise, sleep, and good nutrition—not by buying cortisol-rebalancing teas, which Dr Hameed says are ineffective.
If Your Mum Had a Bad Menopause, So Will You: False
Dr Gillian Goddard, endocrinologist and adjunct assistant professor at NYU Langone Hospital, notes that many women believe their mother's or sister's menopause experiences will predict their own. While genetics influence the timing of the last menstrual period, there is significant person-to-person variability. A mother's difficult menopause does not guarantee the same for her daughter.
You Stop Growing During Puberty: True
Dr Howard explains that after a few years of puberty, enough oestrogen closes the growing ends of bones, halting height increase. Therefore, if concerned about a child's growth, early advice is crucial; most adult height is achieved before puberty, so growth hormone deficiency should be addressed early to impact adult height.
Being Overweight as a Child Can Affect Your Hormones: True
Data from the National Child Measurement Programme for 2024-25 shows 10.5% of children in reception and 22.2% in year 6 were obese. Dr Howard notes clear links between childhood overweight or obesity and earlier puberty timing, as the hypothalamus is not equipped to handle excess weight, leading to inappropriate signals for early puberty.
You Need to 'Balance' Your Hormones: False
Dr Hameed states that the body's hormone levels are exquisitely calibrated with many checks and balances. Dr Goddard adds that hormone fluctuations are normal and maintain homeostasis. The idea of balancing hormones, she believes, stems from the supplement industry, but there is little evidence that supplements have significant hormonal benefits.
Testosterone Only Benefits Men, and Oestrogen Only Benefits Women: False
Dr Jayasena explains that oestrogen plays an important role in male sexual function, and testosterone benefits women. For menopausal women with persistently low libido despite oestrogen and progesterone, adding testosterone can increase libido. In men, testosterone improves sexual function partly by being broken down into oestrogen in fat cells, the brain, and bones.
HRT Is Harmful: False
A 2002 US Women's Health Initiative study on HRT reported increased breast cancer rates, leading to scare stories. However, issues with the study have since emerged, including its focus on older women and use of older synthetic HRT methods. Dr Jan Toledano from the London Hormone Clinic states that modern body-identical HRT is like topping up a petrol tank with the right fuel. The NHS advises extra consultation for those with breast cancer or susceptibility to blood clots, but HRT is generally safe for most women.
Women Gain Weight During Menopause: True
According to the British Menopause Society, weight gain affects at least 50% of women during perimenopause and menopause. Dr Goddard explains that oestrogen tells the body to store fat in hips and thighs; when levels drop, fat stores shift to the midsection, which is metabolically problematic, increasing insulin resistance and risk of diabetes and heart disease. This fat changes carbohydrate processing, creating a cycle of insulin resistance and carb cravings. Women also lose about half a kilo of muscle mass, which is metabolically active. To counter this, Dr Goddard recommends strength training, reducing carbohydrates, and increasing fibre and protein, focusing on holistic health metrics like blood sugar, cholesterol, and blood pressure.
Girls Are Starting Puberty Earlier: True
Dr Goddard notes that girls are entering puberty about a year earlier, but first periods occur only about six months earlier, meaning puberty is lengthening. Theories include better nutrition since the Industrial Revolution, childhood overweight producing more oestrogen, and endocrine-disrupting chemicals in the environment affecting the hypothalamus.
Melatonin Helps You Stay Asleep: False
Melatonin, produced by the pineal gland, regulates circadian rhythm, rising at night. In the UK, it is only available on prescription. Dr Goddard points out that melatonin signals the brain to wind down but does not help with staying asleep or early waking; different sleep disruptions have different causes.
