Obesity is a major risk factor for hypertension (high blood pressure). About three-quarters of primary hypertension cases are directly linked to obesity.

Primary hypertension is high blood pressure without a single clear cause. Instead, it’s linked to several factors, including lifestyle and genetics.

Obesity doesn’t just raise the risk of regular hypertension. It also raises the risk of resistant hypertension, which is high blood pressure that stays high despite treatment.

Most doctors define resistant hypertension as high blood pressure that stays above goal even when a person takes three or more blood pressure medications, often at the highest tolerated doses.

You can have high blood pressure without knowing it because it often doesn’t cause any noticeable symptoms. Here are some ways obesity can raise blood pressure and increase the risk of resistant hypertension.

1. Visceral Fat Puts Pressure on Organs

Visceral fat is a type of fat stored deep inside the body. It wraps around and protects your organs and also stores energy. Although the body needs some visceral fat, too much can put pressure on organs like the kidneys and liver.

Obesity doesn’t just raise your risk of high blood pressure — it also raises your risk of resistant hypertension.

When excess visceral fat presses on the kidneys, they may not work as well as they should. Your kidneys filter blood and balance fluid and salt in the body. They also help regulate blood pressure.

When the kidneys don’t work properly, blood pressure can rise. This is one reason both obesity and chronic kidney disease are linked to resistant hypertension.

2. Remodeled Body Fat Changes Blood Vessels

Obesity involves both gaining and remodeling adipose tissue (body fat). When fat tissue changes, the blood vessels inside it can also change. These changes can damage blood vessels, leading to problems with veins and increasing the risk of high blood pressure and other cardiovascular diseases.

3. Insulin Resistance Can Lead to Fluid Retention

Too much visceral fat doesn’t just put pressure on the organs that help control blood pressure — it can also lead to insulin resistance. Insulin is a hormone that helps move glucose (blood sugar) from the blood into cells, where it is used for energy.

If you have insulin resistance, your cells don’t respond well to insulin, and more glucose stays in your blood. This can lead to high blood sugar and may increase the risk of type 2 diabetes over time. Researchers believe insulin resistance can also raise blood pressure.

When insulin builds up in the blood (called hyperinsulinemia), it can affect how the kidneys work. This can cause the body to hold on to more sodium, resulting in fluid retention. More fluid increases blood volume, which can lead to increased blood pressure.

It’s important to know that some antihypertensives (blood pressure medications), including certain beta-blockers, may make insulin resistance worse. Talk with your doctor about the risks of any medications you take and how they may affect other medical conditions.

4. Increased Inflammation May Play a Role

Obesity can increase inflammation throughout the body, which may contribute to resistant hypertension. Inflammation is a natural response that helps protect the body, such as by fighting infections. However, chronic (long-term) inflammation can damage organs and tissues.

Night after night of poor sleep can cause blood pressure to rise.

Researchers are still studying how this works, but low-grade chronic inflammation is linked to high blood pressure. Certain chemicals released during inflammation may play a role. For example, inflammatory cytokines can affect blood vessels and how the heart and kidneys function, which may raise blood pressure.

5. The Sympathetic Nervous System Becomes Overactive

Excess visceral fat and insulin resistance in people living with obesity can increase activity in the sympathetic nervous system. This system is part of the autonomic nervous system, which controls body functions you don’t have to think about, such as heart rate, blood pressure, and digestion.

The sympathetic nervous system is often called the fight-or-flight system. It becomes active during stress or danger and releases neurotransmitters (brain chemicals) such as norepinephrine and epinephrine (adrenaline).

These chemicals raise heart rate and slow down processes like digestion. Norepinephrine also causes blood vessels to tighten, which can raise blood pressure.

6. Hormone Imbalances Can Raise Blood Pressure

Your body depends on many hormones to function properly. A group of these hormones works together in the renin-angiotensin-aldosterone system (the name lists the hormones).

Adipokines (proteins made by fat cells) help control this system. When too many adipokines are released into the bloodstream, they can increase activity in the renin-angiotensin-aldosterone system.

When excess visceral fat compresses the kidneys, they can’t work as efficiently as they normally do.

When the renin-angiotensin-aldosterone system is overactive, it affects how the kidneys balance sodium and fluid. More fluid in the body means more blood, which can raise blood pressure. Inflammation in blood vessels can also increase, which may further raise blood pressure in people living with obesity.

7. Obstructive Sleep Apnea Can Raise Blood Pressure

Obesity is a risk factor for obstructive sleep apnea (OSA), a condition that involves repeated pauses in breathing during sleep. Excess body fat can press on the airway when you relax, which can block the flow of air. These repeated pauses can wake you up many times during the night, leading to poor-quality sleep.

Sleep plays an important role in blood pressure control, and night after night of poor sleep can cause blood pressure to rise. When breathing stops during sleep, the sympathetic nervous system activates and can cause spikes in blood pressure. Researchers have also found higher sympathetic nervous system activity in people with OSA, even while they’re awake.

On its own, sleep apnea is a common cause of secondary hypertension (high blood pressure caused by another medical condition). It’s also known to contribute to resistant hypertension. OSA can add to inflammation in the body as well.

Together, sleep apnea, inflammation, and increased sympathetic nervous system activity can interact and further raise the risk of obesity-related hypertension.

Talk With Your Doctor

Talk with your healthcare provider about your risk of high blood pressure. You may already have it and not know it, or you may know you’re at higher risk. Your doctor can help you understand your options for managing hypertension.

If you have resistant hypertension, your doctor will want to monitor you closely. Cleveland Clinic notes that in around 40 percent of resistant hypertension cases, medications may not work as expected because they’re not taken as prescribed. Always follow your doctor’s instructions when taking blood pressure medications.

Your doctor may also recommend that you limit salt, get more physical activity, manage conditions like OSA, or make other lifestyle changes to help control your blood pressure.

Join the Conversation

On MyObesityTeam, people share their experiences with obesity, get advice, and find support from others who understand.

How do you manage high blood pressure? Let others know in the comments below.