What is high blood pressure?

Blood pressure measures the force of circulating blood pressing against the artery walls. When the heart beats, it pumps blood toward the arteries and creates tension. Hypertension makes the heart work harder due to the higher resistance in the arteries¹.

As hypertension doesn’t have any symptoms, it is essential to know your blood pressure. It is measured in mmHg, millimetres of mercury^1,2. 

Generally, you have high blood pressure when this number is 140/90mmHg or higher. The ideal range is anywhere between 90/60mmHg and 120/80mmHg². 

Everyone has slightly different blood pressure. You can measure yours at home with the help of this NHS guide or have your doctor do it for you. They can also help you take steps to maintain a healthy level of blood pressure to prevent developing hypertension.

Obesity is a risk factor for high blood pressure 

A person suffers from obesity when they have a body mass index (BMI) of 30 or over. BMI is a person’s weight in kilograms divided by the square of height in meters. You can calculate your BMI here. 

Obesity is the leading risk factor for serious illness, disability and death. The leading causes of mortality worldwide are linked to cardiovascular disease, hypertension, and diabetes³.

The prevalence of obesity is growing and is now understood to be one of the most critical risk factors in the development of hypertension. Around 65% to 75% of hypertension cases are caused directly by excess weight gain⁴.

It is clear from population studies that hypertension and elevated cardiovascular risk are directly related to obesity. However, the underlying mechanisms need to be investigated more adequately⁴. The following part of the article sums up what we know so far.

How does obesity cause high blood pressure? 

Hormonal imbalances and desensitisation

Hormones and hypertension 

The endocrine system is a network of hormone-producing glands that, among other functions, regulate blood pressure. Obesity causes changes in the endocrine system that causes these glands to under or over-perform, resulting in hypertension⁵.

Other ways obesity causes hypertension is by promoting insulin resistance, leptin resistance and activating the Renin-Angiotensin-Aldosterone System^5,6.

Insulin resistance 

Obesity often leads to type 2 diabetes and prediabetes⁷. Your pancreas produces insulin, a hormone that helps your body absorb sugar and use it for energy. When you have type 2 diabetes, you develop insulin resistance, that means your body needs more insulin to do the same job⁷.

As your pancreas tries to create more insulin, it becomes overworked^7,8. Due to insufficient insulin, blood sugar will remain high, damaging or hardening the arteries. This leads to hypertension or worsens already high blood pressure⁸.

Leptin 

Leptin is a hormone that helps you maintain a moderate weight. It signals to the body that you are fully satiated and not hungry anymore⁶. 

People with obesity have high levels of leptin and are resistant to it. Their leptins are dysfunctional and don’t signal to the body the right way anymore. This causes further overeating and weight gain. Furthermore, more fat cells produce more leptin, so the body builds up additional resistance to the hunger-controlling effects of leptin⁹.

Elevated leptin levels combined with the effects of leptin resistance contribute to the development of hypertension^6,9.

The Renin-Angiotensin-Aldosterone System 

One of the other main contributors to hypertension is caused by the improper activation of the RAAS (Renin-Angiotensin-Aldosterone System)⁶. The RAAS plays a vital role in regulating blood volume and pressure. Recent studies show that obesity causes hormone levels to rise within the RAAS¹⁰. This imbalance causes elevated blood pressure and contributes to organ damage^6,10.

Losing excess weight reduces the risk of high blood pressure 

Connect specifically to reducing fats in diet and reducing inflammation

There is a growing need to tackle obesity and manage the health problems that it causes. Being overweight or obese significantly contributes to cardiovascular risk through developing hypertension^11,12.

Studies show that weight gain and weight loss increase and decrease blood pressure, respectively. Weight loss lowers blood pressure because your heart doesn’t have to work as hard to pump the blood around¹¹. It also has a positive effect on other associated risk factors. 

One of the main approaches to managing hypertension is planned long-term weight loss^11,12. The underlying mechanism of how weight loss affects blood pressure has been widely studied in animal and human subjects.

Weight loss results in changes through the following biological mechanisms¹²:

• Reduction in insulin resistance
• Enhanced sodium retention
• Alteration in vascular structure and function
• Changes in ion transport
• Enhanced stimulation of the RAA System
• Changes in natriuretic peptide
• Increased activation of the sympathetic nervous system

Changes in these areas work together and result in the reduction of blood pressure¹².

When dieting, people tend to reduce their calorie intake to lose weight. However, often the results don’t come as expected. The reason for this is the inflammation in the body caused by weight gain¹³. To reduce this inflammation, one has to reduce fats in their diet. The diminishing inflammation helps reduce insulin resistance, resulting in weight loss and lowering blood pressure¹³.

When to contact a doctor 

Having long-standing high blood pressure can have serious consequences. It can damage the organs, kidney disease, dementia, blindness, stroke, and heart attack.

Doctors recommend that adults regularly check their blood pressure. You should contact a doctor if¹⁴:

• Your blood pressure is much higher than usual, such as 180/110mmHg or higher
• Your high blood pressure is causing severe headaches or blurry vision
• Your blood pressure is higher than 140/90 on more than two occasions

Conclusion 

The connection between weight gain and blood pressure is clear: excessive weight gain causes high blood pressure (hypertension). Long-term hypertension poses considerable risk of developing vascular problems, organ damage and heart-related diseases.

Although underlying mechanisms are complex, there are ways to manage hypertension. Losing excess weight helps obese individuals to reduce hypertension-caused risks and maintain a healthy level of blood pressure.

Your doctor can help you make a long-term plan to change your diet and lifestyle to achieve healthy blood pressure.