What Are Hormones and Why Should You Care?

What are hormones and how do they impact your life? Read on to learn more.

When you hear the word "hormones", what's the first thing that comes to your mind? If you think back to the days of sex education in school, the word might bring up some half-remembered lessons about the onset of puberty. But there’s more to hormones than that.

The human body produces many types of hormones, each with a different function in the body. What are hormones, and what effects do they have on the body? The answer is more complex than you might think.

What Are Hormones?

Hormones are the "chemical messengers" of the body. They can coordinate complex processes like fertility, growth, and metabolism. They can also affect your mood and behavior and even play a role in coordinating your immune response.

Hormones are a major driving force in bodily functions. They’re involved in everything from converting food to fuel to changing your body during puberty.

How Do Hormones Send Their Messages?

The way hormones send signals to cells is categorized based on where they act. For example:

  • Paracrine hormones: These hormones are released from an organ and act on nearby cells without needing to enter the bloodstream
  • Endocrine hormones: These hormones act on specific, targeted cells once they're released into the bloodstream from the glands that produce them
  • Autocrine hormones: These hormones act solely on the surface of the cells that secreted them
  • Intracrine hormones: These hormones act solely on the inside of the cells that secreted them

Types of Hormones

Two major types of hormones are peptide hormones and steroid hormones. What does each of these types do? Let's take a closer look.

What Are Steroid Hormones?

Steroid hormones are made from cholesterol. They’re fat-soluble, meaning they can dissolve through fats. Since cell membranes contain fats, they can pass through these membranes. Sex hormones, which we'll discuss in further detail below, are examples of steroid hormones.

What Are Peptide Hormones?

Peptide hormones are made of amino acids, a type of biological building block that makes up proteins. They’re water-soluble and can’t dissolve through cell membranes, which are made mostly of fat. Examples of peptide hormones include insulin and thyroid hormones.

What Are "Sex Hormones?"

Sex hormones are produced to interact with reproductive organs and influence fertility. They affect the body's sexual development, energy levels, and many other systems.

Primary sex hormones are sometimes thought of as "male and female hormones", but the actual delineation is more complex than that. Every human body contains some quantity of all three major sex hormones (testosterone, estrogen, and progesterone), regardless of biological sex.

What Is Testosterone?

Testosterone is produced in the testicles and ovaries, but it's produced in much higher quantities in the testes. Testosterone production ramps up during puberty and begins to decline around age thirty.

How Does Testosterone Affect the Body?

Testosterone directly affects the development of sex organs and the production of sperm, so it plays a critical role in fertility. Testosterone also affects sex drive (libido), hair distribution, bone density, the way fat gets stored, red blood cell count, mood, and muscle mass.

Testosterone During Puberty

During puberty, testosterone causes the testes and scrotum to grow, the penis to lengthen, and pubic hair to grow, typically between the ages of eleven and thirteen. The seminal vesicles and prostate gland begin to enlarge. Facial and underarm hair begins growing around two years after the appearance of pubic hair. Ejaculation usually begins between ages twelve to fourteen years of age.

Testosterone and Aging

Testosterone production begins to decrease after around age thirty. This can reduce your sperm count and affect fertility, as well as other bodily functions like mood, hair growth, and immune response. This is one reason why it may become more difficult to maintain erections as you get older.

Symptoms of Testosterone Deficiency

So, how can you tell if your testosterone levels are low? Symptoms of testosterone deficiency (hypogonadism) include:

  • Reduced energy
  • Decreased libido
  • Depression
  • Hair loss
  • Fragile bones

If you're experiencing these symptoms, it’s a good idea to speak to a healthcare provider to see if low testosterone is to blame.

What Is Estrogen?

Estrogen what most would commonly consider the "female sex hormone", though it is produced in both men and women. Like testosterone, estrogen plays an important role in guiding a body's sexual development and influencing fertility. Estrogen levels spike during puberty, and then rapidly drop off during menopause.

How Does Estrogen Affect the Body?

Estrogen serves many purposes, from regulating menstruation to affecting the texture of the skin. Estrogen also plays a key role in maintaining bone density, controlling cholesterol levels, and even regulating mood. Like testosterone, it also affects where a body stores fat, which aids in the building of breast tissue.

Estrogen During Puberty

The first sign of estrogen changing the body during puberty is usually the development of breast tissue, followed by pubic and body hair growth. The final sign of puberty in women is typically the start of menstruation.

Estrogen and Aging

Estrogen production rapidly decreases during menopause. This may lead to difficulty with temperature regulation (hot flashes), vaginal dryness, and sore breasts. It also often signals the end of menstruation and fertility. The average age for the onset of menopause is around age 40.

Symptoms of Estrogen Deficiency

Some common symptoms of estrogen deficiency include:

  • Hot flashes
  • Decreased libido
  • Vaginal dryness
  • Pain during sex
  • Mood swings
  • Weight management difficulties
  • Thinner hair
  • Fragile bones
  • Dry skin

If you’re experiencing these symptoms well before the onset of menopause, it’s a good idea to speak to a healthcare provider.

What Is Progesterone?

Progesterone is a hormone that has important effects on fertility and pregnancy. Progesterone is produced in the ovaries. In men, progesterone is producedin the adrenal glands, albeit at much lower levels.

How Does Progesterone Affect the Body?

Progesterone helps the uterus lining thicken so that an embryo can implant. It also plays a key role in breast milk production.

Progesterone levels fluctuate during the menstrual cycle. They start out relatively low, then increase after ovulation. If a person becomes pregnant, progesterone levels continue to rise to help support a developing baby. If not, the levels plummet, and the uterus sheds its lining (menstruation).

Progesterone During Puberty

Progesterone's main role during female puberty is to help regulate the menstrual cycle. Progesterone levels increase to help prepare the uterus for a fertilized egg by thickening the uterus lining. In the absence of pregnancy, the thickened lining will get shed, leading to what’s typically called a period.

Symptoms of Progesterone Deficiency

Progesterone levels decrease at the onset of menopause. In the absence of pregnancy or menopause, low levels of progesterone may be indicated by:

  • Hot flashes
  • Severe headaches or migraines
  • Irregular menstrual cycles
  • Depression and anxiety
  • Constant fatigue
  • Vaginal spotting
  • Vaginal dryness

Sex Hormones and Fertility

Sex hormones play a critical role in fertility. In men, low sex hormones can lead to a reduced sperm count and lowered sex drive, both of which make it conception more challenging.

In women, low sex hormones don’t only affect sex drive and the enjoyment of sex, but the ability of the uterus to implant a fertilized egg. It can even affect an implanted embryo’s growth.

Other Causes of Fertility Issues

While low levels of male and female hormones are a common cause of fertility issues, they are not the only ones. Let's break down the potential causes by sex for simplicity.

What Causes Fertility Issues in Men?

Fertility issues in men can come from a wide variety of factors. Some factors leading to male infertility include:

  • Trauma
  • Alcohol use disorder
  • Immune system conditions (autoimmune diseases)
  • Cystic fibrosis
  • Diabetes
  • Cancer and chemotherapy
  • Poor diet
  • Increased stress

What Causes Fertility Issues in Women?

Causes of infertility in women can vary widely. However, some contributors may include:

  • Blocked fallopian tubes
  • Uterine fibroids
  • Poor diet
  • High levels of stress
  • Polycystic ovarian syndrome
  • Cancers and chemotherapy

Since fertility is a two-person job, it’s a good idea for both parties to speak with a healthcare provider before proceeding with any treatments to rule out any other underlying causes.

What Are Hormones? Let's Review

So, let's review: What are hormones? Hormones are the chemical messengers of the body, which play a key role in sexual development, reproduction, and a host of other critical functions. If someone's sex hormone levels are lowered, it can decrease their fertility.