Obesity and hypertension are commonly linked. About 70% of individuals worldwide are overweight or obese, and nearly one in every three adults has high blood pressure, generally known as hypertension.
Is that a Coincidence? Certainly not.
Hypertension is classified as essential hypertension and secondary hypertension. Essential hypertension accounts for 90% of the cases. It is considered idiopathic hypertension in which the cause is not known. The rest of the 10% cases are due to an underlying medical condition.
About 65 – 78% of the individuals with essential hypertension have obesity or are overweight.
Apart from hypertension, obesity is commonly linked with the following conditions:
- Cardiovascular diseases
- Heart failure
- Polycystic ovarian syndrome
- Prostatic cancer
- Endometrial cancer
- Colon cancer
- Breast cancer
Obesity and Hypertension:
Obesity is defined as having a body mass index (BMI) of more than 30 kg/m², and it is a primary risk factor for high blood pressure. Your heart has to work harder to pump blood through your body if you’re overweight or obese.
However, this overload puts a strain on arteries. As a result of the arteries resist the flow of blood, and ultimately the blood pressure rises.
Obesity is a major contributor to high blood pressure. According to the Framingham Heart Study, obesity is directly responsible for around 78 percent of hypertension cases in men and 65 percent of hypertension cases in women.
Obesity and hypertension, when combined, form a major cause of cardiovascular disease.
Obesity also puts a burden on your kidneys, which puts an even greater strain on your heart. When you’re overweight and your blood pressure is too high, the tiny blood vessels in your kidneys are damaged.
The arteries’ walls thicken and restrict blood flow, making it more difficult for your kidneys to filter your blood and remove waste and fluids. Your heart needs to work significantly harder when your body is unable to eliminate excess fluid.
You can take steps to lower your blood pressure, but if you have obesity, you may need to make various lifestyle modifications in addition to taking antihypertensives, which are blood pressure medications.
Weight Gain and Hypertension
Increased blood pressure is almost always linked to weight gain. The quantity of weight gain is directly related to the increase in blood pressure, and even mild weight gain is linked to an increased risk of developing hypertension.
However, the BP response to weight gain is variable among individuals, and not all obese people become hypertensive. Furthermore, weight loss is linked to lower blood pressure in many obese people who are not hypertensive. As a result, BP in obese people is higher than that in lean people.
How Does Obesity Cause Hypertension?
Some mechanisms that are undergone in the body as a result of increased weight might lead to elevated blood pressure. Some of them are:
Increased Cardiac Output:
Animal studies show that weight gain increases cardiac output and blood flow to adipose tissue and various other organs (e.g., heart, kidney, muscle, gut)). This appears to be the case with humans as well.[Ref]
In highly obese people, resting cardiac output might approach 10 liters per minute. In obese humans, a higher stroke volume and heart rate result in a higher cardiac output at rest. [Ref]
Obesity Causes Alterations in Sympathetic Activity:
Increased SNS activity has been linked to obesity and hypertension in several studies). SNS activity, particularly renal sympathetic nerve activity (RSNA), is higher in fat people. It has been shown that pharmacological adrenergic inhibition lowers blood pressure in obese people more than in lean people. [Ref]
Dysfunction of Baroreflex:
The arterial baroreflex is important in the acute regulation of SNS outflow and blood pressure. However, the importance of arterial baroreflex in the long-term regulation of SNS outflow and blood pressure has been disputed.
When obese hypertensive people are compared to obese normotensive and lean hypertensive subjects, the capacity of (acute) pharmacologically produced elevations in BP to control SNS activity is diminished. [Ref]
Increased Production of leptin:
Leptin, which is produced by the OB gene, is secreted from adipocytes to fat mass and acts on hypothalamic neuronal targets to change energy intake and expenditure. Studies suggest that plasma leptin concentrations are higher in hypertensive compared with normotensive individuals. [Ref]
Treatment options for obesity-related hypertension
The treatment goals for obese individuals with hypertension or obesity-related hypertension are aimed to:
- Control blood pressure so as to lower the cardiovascular risk factors
- Reduce weight that may result in reversal of hypertension as well as lower the cardiovascular risk factors.
The initial treatment of hypertension in obese individuals is weight reduction. A low caloric diet, low salt intake, and regular aerobic exercise are considered as the initial nonpharmacologic treatment options.
Non-pharmacological treatment of Obesity and Hypertension:
In obese hypertensives, weight loss is regarded as the most effective nonpharmacological therapy for decreasing blood pressure. The degree of weight loss and the reduction in BP have a dose-response relationship that is independent of salt consumption.
Studies conclude that even small weight loss of 5-10% of body weight is linked to clinically substantial reductions in blood pressure. With each 1 kg loss in body weight, systolic and diastolic blood pressure drops by 2 and 1 mmHg, respectively. [Ref]
Regular Physical Activity:
Hypertension is more common in obese sedentary people than in lean physically active people. When compared to sedentary people, physically active people have a lower risk of hypertension.
Importantly, the risk of developing hypertension as a result of weight increase appears to be lower among physically active people. As a result, people with high blood pressure should engage in frequent physical activity.
Numerous studies show that regular aerobic exercise reduces systolic and diastolic blood pressure in hypertensive people by as much as 10 and 7 mmHg, respectively. [Ref]
Sodium Restriction (Low Salt):
Obesity-related hypertension is considered a sodium-sensitive form of hypertension, although there is no complete agreement on this issue. Many studies suggest that sodium restriction reduces BP in obese individuals. [Ref]
Pharmacologic Treatment of Obesity and Hypertension:
Although some have indicated that therapy should be chosen depending on the cause of the condition, there are currently no particular recommendations for the pharmacological treatment of obese hypertension.
If obesity is an underlying cause of essential hypertension, as it appears to be, pharmaceutical therapy of obesity may be a rational strategy to lowering BP in obese people.
Six classes of drugs have been approved for the long-term treatment of obesity and weight loss. These include:
- Orlistat (Xenical)
- Qsymia (Phentermine/ Topiramate)
- Contrave (Naltrexone/ Bupropion)
- Belviq (Lorcaserin)
- Liraglutide (Saxenda, Victoza)
- Semaglutide (Wegovy)
Among these medicines, Lorcaserin has been discontinued because of its association with certain cancers (colon, breast, and skin)
Qsymia should be avoided in individuals with obesity and hypertension. Qsymia contains phentermine which is a sympathomimetic drug. It activates the sympathetic nervous system resulting in hypertension.
Antihypertensive Medicines in patients with obesity and hypertension:
There are no specific drug choices in patients with obesity and hypertension. However, calcium channel blockers cause fluid retention and constipation. These drugs may be associated with weight gain and hence avoided.
Examples of commonly used calcium channel blockers:
- Amlodipine (Norvasc)
- Nifedipine (Adalat)
- Nicardipine (Cardene)
- Verapamil (Calan)
- Diltiazem (Cardizem)
ACE-Inhibitors and ARBs in combination with hydrochlorothiazide may be preferred as these drugs may result in loss of sodium from the body. Obese people with edema may benefit when ACE Inhibitors and ARBs are combined with hydrochlorothiazide or other diuretic medicines.
Prevention of obesity and hypertension:
Preventing weight gain should be a main therapeutic goal in the fight against hypertension. Weight gain in normal-weight participants is reduced by regular physical exercise and reduced dietary fat intake while weight regains after weight loss is reduced in obese persons.
Most people could avoid weight gain if they increased their regular physical exercise and reduced their energy consumption by 100 calories per day.
Small lifestyle modifications, such as adding 15 minutes of daily exercise and reducing portion sizes by a few bites per meal, could help. If successful, lifestyle changes like the one recommended might help in the prevention of obesity and hypertension.
Obesity and hypertension are commonly linked. Most obese patients have hypertension. Treatment should be aimed towards weight loss, salt restriction, and drugs to lower blood pressure.