Why is VAT important?
The biggest misconception about body fat is that it’s always dangerous and unhealthy. Certain levels of VAT are important because they help protect your organs, surround important blood vessels, and supply blood to abdominal organs. As it cushions the organs, VAT can prevent damage. However, too much VAT is not good for you and may lead to major health problems. Since it can actively increase the risk of health problems, visceral adipose tissue is often referred to as “active fat.”
Dangers of VAT
While visceral adipose tissue protects your organs, having too much of it is bad news for your health. Evidence confirms that visceral or central obesity is directly associated with multiple pathological conditions, including:
● Impaired glucose and lipid metabolism
● Insulin resistance
● Higher risk of colon, breast, and prostate cancers
Moreover, visceral obesity is also linked to prolonged hospital stays, increased risk of infections, complications, and mortality in hospitals. Visceral obesity is an independent component of metabolic syndrome and increases the risk of cardiovascular diseases. Additionally, VAT is a hormonally active tissue, thus being capable of releasing different bioactive molecules and hormones such as:
● Adiponectin (a hormone released by adipose tissue to help with insulin sensitivity and inflammation)
● Leptin (hormone that manages energy levels and signals your brain when you need food or you’re full)
● Tumor necrosis factor (TNF) (inflammatory cytokine)
● Resistin (hormone involved in insulin resistance and inflammation)
● Interleukin 6 (chemical active in inflammation and immunity)
Visceral adipose tissue and insulin resistance
One of the many health effects of excess VAT is increased insulin resistance. The term insulin resistance refers to impaired insulin sensitivity, which happens when cells in muscle, liver, and fat fail to respond to insulin properly and can’t take up glucose from blood easily. Insulin is a hormone that allows blood glucose to enter cells and provide energy. Reduced insulin sensitivity impairs the regulation of blood glucose and may pave the way to type 2 diabetes.
When you’re insulin resistant, your pancreas proceeds to make even more insulin in the hope of overcoming the growing blood glucose levels. This process is called hyperinsulinemia. When cells become too resistant to insulin, blood glucose levels keep going up.
Insulin resistance is a common problem. Evidence shows that over 40% of U.S. adults aged 18 to 44 years are insulin-resistant.
People develop insulin resistance for several reasons, such as a sedentary lifestyle, unhealthy diet, and even certain medications (e.g., certain blood pressure medications). One of the biggest causes of insulin resistance is excess visceral fat.
A paper from Current Opinion in Endocrinology, Diabetes, and Obesity reported that visceral adiposity correlates with excessive lipid accumulation in the liver. Excessive buildup of lipids may contribute to insulin resistance through cell-autonomous mechanisms, inflammation, and production of inflammatory cytokines.
The same paper explains that visceral fat is inherently diabetogenic. That happens because VAT secretes adipokines that disrupt insulin sensitivity in muscle and liver. Plus, VAT accumulates macrophages (cells of the innate immune system) that cause inflammation and thereby impair sensitivity to insulin.
Additionally, a study from Diabetology and Metabolic Syndrome confirmed that abdominal adiposity was strongly associated with insulin resistance and metabolic syndrome in non-diabetic adults. This was particularly the case with intraperitoneal (IP) fat, which strongly correlated with systemic metabolic variables such as plasma insulin, blood glucose levels, glucose disposal rate, and systolic blood pressure. The IP fat refers to adipose tissue in the abdominal cavity.
When it comes to visceral adipose tissue and its effect on metabolic profile, it’s important to mention diabetes too. Insulin resistance, when left unmanaged, can lead to type 2 diabetes and significantly jeopardize your health and well-being. One study found that visceral fat mass has a stronger link with diabetes and prediabetes than other anthropometric obesity indicators.
A paper from Frontiers in Endocrinology suggested that abdominal obesity, specifically VAT, is related to a higher risk of type 2 diabetes than peripheral obesity. The reason behind this relationship is that expanded VAT affects insulin metabolism by releasing free fatty acids in the portal circulation.
Furthermore, a study from the Journal of Clinical Endocrinology and Metabolism revealed that in people with type 2 diabetes, accumulation of visceral fat exhibits a negative effect on glycemic control. Potential mechanisms of action include a reduction in peripheral insulin sensitivity and enhanced gluconeogenesis (the process of transforming non-carbohydrate compounds into glucose). In other words, not only can excess visceral fat increase the risk of insulin resistance and type 2 diabetes, but it also worsens these problems in people who already have them.
Visceral adipose tissue and cancer
Cancer is a serious disease that develops when cells divide abnormally and spread into surrounding tissues. The American Cancer Society estimates that over 2 million new cancer cases and more than 611,720 deaths are projected to occur due to cancer in the United States.
The most common cancers are lung, breast, colon, rectum, and prostate cancers. Various factors increase the susceptibility to develop cancer. Some of these include smoking, UV exposure, excessive alcohol intake, and being overweight or obese. Indeed, excess VAT is a significant risk factor for this severe disease and one of many reasons to do your best to keep it in a healthy range.
A paper from Nutrients reported that excessive accumulation of adipose tissue is a risk factor for many chronic diseases, including cancer. The development of a tumor has a lot to do with adiposity, chronic low-grade inflammation, and hyperinsulinemia.
Moreover, a study from Translational Cancer Research found a clear link between visceral obesity and breast cancer in postmenopausal women. Underlying mechanisms of action could be VAT’s impact on insulin action, higher levels of free fatty acids, lower levels of sex hormone binding globulin levels, and increased bioavailability of estradiol, all of which are associated with a higher risk of breast cancer. Plus, VAT could contribute to breast cancer through increased estrogen levels derived from the aromatization of androstenedione (a steroid hormone) within fat stores.
In addition to increasing breast cancer risk, visceral adipose tissue can also worsen the course of the disease. Nutrition and Cancer published an excellent paper, which gave more insight into this relationship. The paper showed that a high level of visceral fat in female patients with breast cancer is linked to shorter disease-free survival after adjuvant chemotherapy.
Effects of visceral adipose tissue extend beyond breast cancer. Having too much visceral fat could also contribute to or worsen colon cancer. Evidence shows that having too visceral fat is related to colorectal cancer in postmenopausal women. The presence of excessive visceral fat can worsen disease severity too. For instance, visceral fat increases the risk of colorectal cancer-specific mortality and metastasis.
Men with excessive visceral adipose tissue are more likely to develop prostate cancer. Several mechanismsare involved in the relationship between VAT and prostate cancer, including steroid hormone disturbances, action of adipocytokines secreted by visceral fat cells, and higher levels of insulin and other hormones.
A study from the journal Cancer reported that in all men (1832) who participated in the study, visceral fat and thigh subcutaneous fat were linked to the risk of advanced and fatal disease. Among leaner men, visceral adipose tissue was associated with advanced and fatal disease. The researchers explained fat distribution could be a significant prognostic factor for prostate cancer outcomes by serving as a marker for inflammatory, hormonal, and metabolic factors in prostate carcinogenesis. For example, VAT is inversely connected to bioavailable testosterone and adiponectin and more strongly linked to pro-inflammatory cytokines and insulin resistance, which may influence the progression of prostate cancer.
Visceral adipose tissue and cardiovascular health
Cardiovascular disease is the leading cause of death across the globe, according to the World Health Organization (WHO). There are different types of cardiovascular disease, including coronary heart disease (CHD), stroke, peripheral arterial disease, and aortic disease. People can develop cardiovascular diseases due to various reasons ranging from unhealthy diet and smoking to excessive visceral adipose tissue.
Frontiers in Cardiovascular Medicine published a paper that suggested that visceral adiposity could contribute to cardiometabolic risk and atherosclerosis due to dyslipidemia, inflammation, glycemic abnormalities, insulin resistance, and vascular disturbances.
The presence and severity of visceral fat is associated with the severity of coronary artery plaque, according to a study from the journal Obesity. Moreover, one population-based study found a higher risk of all conditions associated with visceral fat, including hypertension, diabetes and prediabetes, hypercholesterolemia, and hypertriglyceridemia. The harmful effect of VAT on cardiovascular health is more pronounced in women than men.
Excessive visceral fat jeopardizes your cardiovascular health by worsening metabolic functions. This explains why doctors advise patients to reduce body fat percentage, especially in the abdominal area, to improve heart health, manage current cardiovascular problems, or prevent these issues. Keep in mind that excess VAT paves the way to chronic inflammation and dysregulates your metabolism, which affects cardiovascular health.
Visceral adipose tissue, gut health, and the immune system
Your gut breaks down food and absorbs nutrients to support functions in your body. The gut microbiome, or gut microbiota, consists of both good and bad bacteria and microorganisms. Balance of these microorganisms is necessary for optimal gut health, digestion, energy recovery from the metabolism of non-digestible food components, and protection of a host (you) from pathogens. Indeed, a healthy gut equals a strong immune system. What’s more, 70% to 80% of the immune system’s cells reside in your gut.
When your gut isn’t healthy, consequences are felt in digestive function, bowel movements, and even your immune system’s defenses. Your immunity may weaken, thus making you more susceptible to illnesses.
A wide range of factors can affect gut health, and the immune system and VAT are among them. A paper from Frontiers in Cellular and Infection Microbiology reported that visceral fat is more closely correlated with gut microbiome compared to BMI and waist circumference. There is a strong connection between gut microbiome, VAT, and metabolic disorders. Excess visceral fat is more active in storing dietary fatty acids and secreting inflammatory compounds. At the same time, the metabolites of gut microbes in obese people are involved in the inflammatory response. This could explain why VAT can harm gut health – by triggering inflammation.
Visceral fat can decrease the number of good bacteria in gut microbiota. Evidence shows that excess VAT is associated with a decreased abundance of Bifidobacterium, which is a good bacteria. These bacteria are probiotics that help digest fiber and prevent infections. They keep your gut healthy. Having too much visceral fat can jeopardize these important bacteria and impair balance in gut microbiota.
In a study from the American Journal of Gastroenterology, visceral adiposity was associated with a higher risk of irritable bowel syndrome (IBS), particularly of IBS-D (irritable bowel syndrome with diarrhea). This further explains the damaging impact of excess VAT on gut health.
The connection between VAT and immune health goes beyond gut microbiota itself. A paper from BMC Medicine explains that both innate and adaptive immune system cells are found in visceral fat. In a healthy, non-inflamed tissue, these cells protect us from infection, but they also support tissue function. Excessive visceral adipose tissue may cause readjustment of its structures, which affects the immune system’s cells too. Having too much visceral fat can lead to inflammation, which may decrease the immune system’s defenses.
The effects of excess VAT extend to increased susceptibility to viral infections and their severity. For example, visceral fat is linked to the severity of COVID-19 due to its impact on inflammatory response.
In the next articles, we wil discuss, how you can measure VAT, what a “normal” level is, and how you can reduce it.
Did you know? The only way to know whether you have excessive VAT is to schedule your DEXA scan. You can do so with Fitnescity. Through access to your personal dashboard, you can track progress and modify your lifestyle to reach your goal and reduce VAT successfully.