You may not know much about your hormones, but they have a huge impact on so many aspects of your health, including your mood, your sex drive, and yep, your weight.

What exactly are these all-powerful chemicals? Hormones are chemical messengers that travel through our bodies to trigger all kinds of complex bodily processes, says Florence Comite, M.D., an endocrinologist and founder of Comite Center for Precision Medicine. (And—surprise!—you have about 50 of them.) When our hormones work together properly, they do everything from regulating our metabolism to helping us reproduce to balancing our sleep cycle and mood.

But when these chemical messengers are disrupted, the effects throughout our body can be dramatic, according to Sara Gottfried, M.D., the three-time New York Times bestselling author of The Hormone Cure, The Hormone Reset Diet and Younger. Out-of-whack hormones can lead to a slew of symptoms, including fatigue, sugar cravings, trouble losing weight, bloating, increased belly fat, trouble sleeping, anxiety, irritability, and constant stress.

When it comes to our waistlines, there are seven standout hormones that, well, carry more weight. So if you’re packing on the pounds with zero explanation, these hormones may be to blame.

1. Ghrelin

Nicknamed the ‘hunger hormone,’ ghrelin is secreted from your stomach lining when your stomach is empty or not taking in enough energy through food, and signals to your brain that you need to eat, says nutritionist Susan Stalte, R.D.

We release more of this hormone when we regularly skimp on sleep, which can lead to higher calorie consumption, and an even more sedentary lifestyle, according to a study published in PloS Medicine. And a more voracious appetite makes it  more difficult to keep off excess pounds when it’s coupled with fewer workouts.

Related: Shop supplements that support a healthy snooze.

To keep your ghrelin, eating habits, and exercise routine all grooving, Stalte recommends aiming for seven to eight hours of sleep per night, avoiding processed foods, and eating a balance of fiber, healthy fats, and high-quality protein to stabilize your blood sugar and keep you feeling satisfied.

2. Cortisol

Cortisol is the body’s main stress hormone. It’s released whenever your body senses it needs to enter ‘high-alert mode’—whether you’re facing a major work deadline, fighting with your significant other, or even just hammering away in the gym. It’s also release when you lose out on sleep, according to research published in Sleep.

“Cortisol raises blood pressure and blood sugar to power your muscles and help you run,” says Gottfried. Basically, the hormone suppresses all body processes (like your immune response, digestion, and reproductive function) that would be nonessential in a true flight-or-fight situation, according to The Mayo Clinic.

While cortisol may help your body handle some sort of threat or stress in the short-term, it becomes an issue if it’s chronically elevated. “Cortisol becomes poison, causing you to store belly fat, deplete your ‘happy’ brain chemicals like serotonin, and lose sleep,” Gottfried says. These issues can snowball and lead to headaches, anxiety, depression, and digestive problems long-term. Elevated cortisol levels are also linked to food addiction and sugar cravings, and leave you more likely to reach for processed, unhealthy foods, she says.

To support healthy cortisol function, evaluate and manage the stress in your life, The Mayo Clinic recommends. Try practicing yoga, meditation, getting a massage, or seeing a counseling professional to help get symptoms under control.

3. Estrogen

Estrogen, the primary female sex hormone, is responsible for the development of the female reproductive system—and its fluctuations during a woman’s menstrual cycle cause minor ebbs and flows in water weight. Research also suggests that estrogen regulates body fat distribution and food intake, according to a review published in The Journal of Steroid Biochemistry and Molecular Biology.

During women’s transition to menopause in middle age, a drop in estrogen leads to some weight gain (typically about five to eight pounds), according to Mary Jane Minkin, M.D., clinical professor in the Department of Obstetrics, Gynecology, and Reproductive Sciences at the Yale University School of Medicine. These pounds are often gained around the midsection. (Not only is fat around the middle more difficult to lose, but it also increases your risk for cardiovascular disease, stroke, and type 2 diabetes.)

Some women use estrogen replacement therapy to help offset the weight gain associated with menopause (along with other symptoms like hot flashes and night sweats), Minkin says. Menopause-related estrogen declines are inevitable, so women should talk to their docs about whether hormone replacement therapy may be right for them. Minkin also recommends that women in or post-menopause exercise regularly, since muscle mass helps keep our metabolisms revved and can help ward off fat-gain.

Related: 7 Natural Ways To Kick-Start Your Metabolism

Men, who have some estrogen in their systems, don’t get off scot-free, though. According to research published in the New England Journal of Medicine, men derive estrogen from testosterone, so as their testosterone levels fall in middle age (more on that in a second), so do estrogen levels. This decrease in estrogen can contribute to an increase in belly fat for many men (like women), the study says.

4. Testosterone

Now that you’ve got ‘T’ on the mind, let’s get to it. Though it’s present in both men and women, testosterone is the primary male sex hormone and supports muscle mass, bone mass, strength, and reproductive function.

When testosterone levels take a downturn, muscle mass, metabolic rate, and energy levels all decrease, according to nutritional biochemist and author Shawn M. Talbott, Ph.D. All of these factors lead to us burning fewer calories and likely gaining belly fat, he says.

Chronic stress and lack of sleep can diminish testosterone, but levels also dip as we age, says Talbott. This drop occurs in both men and women, though we typically think of ‘low-T’ as a guy thing. (Most guys’ testosterone starts to decline in their 40s.)

Testosterone replacement therapy can help offset some of the muscle mass loss many men experience as they age and address other low-T-related issues, like fatigue, according to research published in Current Opinion in Endocrinology, Diabetes, and Obesity.

 5. Thyroid Hormones

Your thyroid, which is a teeny gland located at the base of your neck, has a huge impact on the rest of your body. The thyroid makes two hormones, free thyroid 3 (T3) and free thyroid 4 (T4), which regulate our metabolism (the rate at which we use energy), affect the growth, and control how quickly we make proteins and how sensitive we are to other hormones, says Comite.

Lifestyle factors—particularly high levels of stress—can affect thyroid function, and when thyroid hormones go haywire, trouble ensues. The two main issues: Not producing enough thyroid hormones (called ‘hypothyroidism’) or producing too much (called ‘hyperthyroidism’).

Drops in T3 and T4 in hypothyroidism can slow your metabolic rate and lead to weight gain, says Talbott. Meanwhile, hyperthyroidism can speed up your metabolic rate and cause sudden weight loss and nervousness. Wonked-out thyroid hormones also throw off thyroid-stimulating hormone (TSH), which signals to the thyroid to work harder. TSH shoots up in hypothyroidism up and drop in hyperthyroidism, Comite says.

Related: Could You Have A Thyroid Issue?

Typically docs use a blood test to determine TSH levels and identify a potential thyroid issue. From there, they may do a number of things to get the thyroid chugging along at the proper pace. Treatments for hypothyroidism may include taking synthetic thyroid hormones, while treatments for hyperthyroidism may include radioactive iodine therapy or thyroid hormone blockers, along with prioritizing a healthy lifestyle, according to the American Thyroid Association.

6. Insulin

Insulin is a hormone made in the pancreas that allows your body to use glucose (a.k.a. sugar) for energy, says Comite. When you eat or drink something that contains sugar, your body releases insulin to clear that sugar from your blood and shuttle it to your tissues (like muscles) for use.

When your cells become numb to insulin, you develop insulin resistance and instead of shuttling glucose from your blood into your cells, your liver converts that sugar into stored fat, says Gottfried. The condition is often marked by intense sugar cravings and weight gain and experts believe excess weight and inactivity are both major factors in causing it, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

Docs can test your insulin levels and level of insulin resistance with a series of blood tests after an overnight fast and then periodically after drinking a sugary drink.

Losing weight and exercising can help your body become more sensitive to insulin, according to the NIDDK. Your doctor may also prescribe a medication to help control blood sugar levels.

7. Leptin

Another big influencer on hunger and satiety is leptin, which Gottfried calls ‘nature’s appetite suppressant.’ “Under normal conditions, leptin signals your brain to stop eating once you’ve had enough,” she explains.

Leptin is released from fat, so research suggests that adequate leptin signals to our body that we have enough fat and aren’t starving, and consequently don’t need to take in tons of calories, according to a review published in Obesity.

However, when leptin levels (and body fat) keep rising, your receptors stop functioning properly and you never quite get the leptin cue that you’re satisfied, which—annoyingly—leaves you feeling hungry, says Gottfried. Known as leptin resistance, this predicament leaves you more likely to nosh on unhealthy foods and can cause weight gain to snowball. In fact, research has identified leptin resistance as a major player in obesity.

Your doc can identify leptin resistance through a simple blood test, says Stalte. From there, you’ll want to work with a dietitian to revamp your diet, she says.