What are the effects of hormones on the body and skin?

Starling's original definition of a hormone in 1905 was: "a hormone is a substance produced by internally secreting glands, which serve to transmit signals through the blood to target organs".

Nor do the new definitions cover the full meaning of hormones as specific carriers of information. A major problem is the lack of distinction between hormones and other signaling molecules such as cytokines, growth factors or autacoid compounds.

However, it seems that a precise definition is not even possible, as some cytokines and growth factors act like hormones under certain conditions!

In this article, we'll be focusing on the recognized hormones, which are essential chemical messengers that govern the complex functioning of the human body.

Released by the endocrine glands, these substances play a central role in the regulation and coordination of physiological functions. To explore in depth the effects of hormones on the body, we examine and explain the different hormonal categories and their specific impact.

 

1. Sex hormones: the pillars of reproduction

Sex hormones, notably estrogen and progesterone in women, and testosterone in men, are crucial for the development of secondary sexual characteristics.

Secondary sexual characteristics are distinct physical traits that develop during puberty and differentiate male and female individuals of a species. These characteristics are not directly linked to reproduction, unlike primary sexual characteristics such as genitalia, but they do play an essential role in signalling sexual maturity.

Secondary sexual characteristics emerge under theinfluence of sexhormones, mainly estrogen and progesterone in women, and testosterone in men.

For women :

• Breast development: under the influence of estrogen, the mammary glands develop, leading to the formation of breasts. This is one of the first visible signs of puberty in girls.
• Pubic and axillary hair growth: Sex hormones stimulate hair growth in the pubic area and under the armpits, signaling the onset of puberty.
• Body fat distribution: Estrogen influences fat distribution, often leading to an increase in body fat around the hips and thighs.
• Widening of the hips: Puberty often induces a widening of the pelvis, contributing to the distinctive feminine silhouette.
• Onset of menstrual cycle: The onset of menstruation is a key secondary sexual characteristic, marking potential reproductive capacity.

 

Men's category:

• Breast growth: Although less pronounced than in women, a small amount of breast tissue can develop in men during puberty.
• Facial and body hair growth: Testosterone stimulates hair growth on the face, legs, chest and other areas of the body.
• Broader shoulders and jaw: Testosterone promotes muscle development, often resulting in broader shoulders and more defined jaws.
• Adam's apple growth: A cartilaginous protuberance called the Adam's apple becomes more pronounced in men during puberty.
• Enlarged genitalia: Puberty induces growth of the external genitalia, including the penis and testicles.
• Voice changes: Testosterone causes the vocal cords to thicken, leading to a significant drop in voice during puberty.

Secreted by the ovaries and testes, sex hormones regulate the menstrual cycle, spermatogenesis and thus the process of sperm development, and are essential to reproduction. In women, the ovaries produce estrogen and progesterone, regulating puberty,ovulation and the menstrual cycle.

2. Thyroid hormones: architects of metabolism

Thyroid hormones, such as thyroxine (T4) and triiodothyronine (T3), secreted by the thyroid g land, orchestrate metabolism. They influence energy consumption, organ growth and development, ensuring hormonal balance and proper body function. Thyroid hormones are also essential for brain development during gestation.

3. Peptide hormones: rapid regulators

Peptide hormones such asinsulin andadrenalin, secreted by the pancreas and adrenal glands, regulate glucose metabolism, stress response and other processes. The pancreas, through insulin, regulates blood glucose levels, while the adrenal glands produce adrenaline, triggering the "fight or flight" response in the event of acute stress.

4. Derived hormones: specific origins

Certain hormones, such as melatonin produced by the pineal gland, have specific origins. They influence the circadian cycle, regulating sleep and wakefulness. These derived hormones, often linked to the nervous system, illustrate the diversity of hormonal sources in the human body.

5. Endocrine gland: master of hormones

Endocrine glands, including the thyroid, adrenal glands and pancreas, ensure the secretion and release of hormones. As hormonal command centers, they constantly adjust hormone levels to meet the body's physiological needs.

Thehypothalamus andpituitary gland, key components of the endocrine system, regulate hormone secretion and maintain hormonal balance.

6. Growth hormone: a development gas pedal

Growth hormone, produced by the pituitary gland, stimulates tissue growth and development. It plays a crucial role in growth in children and tissue regeneration in adults. Growth stimulation occurs mainly during deep sleep.

 

7. Steroid hormones: key players in the endocrine system

Steroid hormones, such as cortisol and sex hormones, are derived from cholesterol. Secreted by the adrenal glands and gonads, they regulate functions ranging from stress response to metabolic control. Sex hormones, such as testosterone, are responsible for the development of secondary sexual characteristics.

8. Hormone therapy and gender transition

Transgender people have a gender identity that differs from their sex assigned at birth. For many transgender people, access to gender-affirming hormone therapy (GAHT) is an important and medically necessary step in their gender transition.

For trans-men, masculinizing hormone therapy involves testosterone treatment. Testosterone can be injected under the skin or into the muscle, or applied as a gel or skin solution. Other hormone treatments may also be prescribed.

For trans-women, feminizing hormone therapy consists of :

• Anti-androgens, in the form of tablets or, more rarely, injections, to reduce male hormones.
• Estrogen
• Progesterone

The choice of treatment depends on the doctor's recommendations and the patient's preferences. There is no evidence that one approved way of administering treatment is more effective than another.

What are the physical effects of hormones?

Hormones induce physical changes that are in harmony with gender identity.

Most changes can be observed over a 2-year period. The speed and quality of change varies from person to person.

Feminization and masculinization regimens are safe when used within established hormonal protocols and are associated with significant improvements in mental health outcomes, including reduced depression, anxiety and gender dysphoria.

What are the effects of hormone therapy on the skin?

The effects on the skin vary according to the type of transition, and therefore the hormone therapy chosen.

Hormonal therapy can have two major effects on your skin:

• An epidermis that produces fewer lipids, and therefore less fat: skin is drier, and problems associated with oily or combination skin (blackheads, adult acne, etc.) tend to diminish. This is often the result ofinhibiting male hormones in favor of female hormones;
• Or, on the contrary, a higher production of sebum, linked to an increase in male hormones in the body. Skin becomes thicker and oilier, and imperfections may set in.

In trans-men, increased hair growth can lead to ingrown hairs: the skin reddens locally, inflammation occurs, and in some cases, a small hard ball appears under the skin.

How do you care for your skin during a gender transition?

The beauty routine remains essentially the same:

1. Cleanse your skin twice a day to eliminate impurities
2. Moisturize the face with a skincare product adapted to skin changes: a rich cream for dry skin and an anti-imperfection mattifying cream for skin that becomes oily.
3. Use a purifying exfoliating scrub and mask once or twice a week to stimulate cell renewal and refine skin texture.

You can focus on certain assets:

• Salicylic acid for its immediate exfoliating action on the stratum corneum, reducing the number of imperfections.
• Zinc gluconate to regulate upstream sebum production, reduce shine and eliminate blackheads

For dry skin, apply a cream rich in lipids and ceramides.

9. Hormone replacement therapy

Hormone replacement therapy (HRT) involves supplementing women with hormones that are lost during the menopausal transition. To relieve symptoms associated with menopause, conventional HRT includes a component ofestrogen and progesterone to mimic the hormones produced by the human ovary. There are many estrogen-based therapies, including those naturally present in the humanovary, such as estradiol and estriol. Other estrogenic compounds include conjugated equine estrogen (CEE), the most commonly prescribed estrogen in the USA. They are not identical in their effect on the human body, but share the same FDA indications.

Conclusion

Hormones, governors of homeostasis, direct a sophisticated ballet in the human body. Each category of hormone, whether sex, thyroid, peptide, derivative, endocrine, growth or steroid, makes a unique contribution to maintaining physiological equilibrium. Secretion, stimulation and reception by hormone receptors are crucial elements in this complex chemical dance, illustrating the subtlety of hormone regulation. This in-depth understanding is essential to appreciate the sophistication of endocrine systems and their implications for global health.

Sources

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3. Stárka L, Dušková M. What is a hormone? Physiol Res. 2020 Sep 30;69(Suppl 2):S183-S185. doi: 10.33549/physiolres.934509. PMID: 33094616; PMCID: PMC8603735.