Metabolic Health

Subcutaneous vs. Visceral Fats

Here’s why some types of body fats might make us healthier and others unhealthier when not balanced with lifestyle choices.

Characterizing something as “good or bad” is contextual. Judging what nature gives us as “bad” does not make sense. Nature has evolved over billions of years to give us a sophisticated and functioning body. Any bodily feature and biological behavior must have a purpose or benefit.

From a psychological angle, while body fat is a necessary part of our biology, society’s negative attitudes or the perception of overweight people comparing themselves with others can create unnecessary stress, as I documented in a previous article.

Fat is one of the essential molecules for the body. However, studies indicate that excessive amounts of fats accumulated in specific body parts can cause cardio-metabolic disorders through hyperlipidemia and chronic inflammation.

Fat pathophysiology is highly complex. Despite years of studies, scientists still cannot agree on the impact of various fat types. However, a growing body of knowledge categorized stored fats and shed light on their impact and implication for our health.

Different body fat types might have different health effects. The impacts and implications of stored fat depend on location, metabolic activity, hormonal activity, and evolutionary history.

Subcutaneous fat and visceral fat are two different types of adipose tissue located in different body parts and have distinct metabolic and health impacts and implications that I cover in this story.

By understanding various factors, scientists and clinicians develop targeted strategies for managing body fat and reducing the risks of cardio-metabolic disorders and other health issues. I touch on them briefly.

I overview fats stored in various body parts and discuss their mechanisms, impact, and implications for our health and well-being at a high level without going too much into scientific and technical details. This story is about stored fat in the body, not dietary fats, which I covered in a previous article.

I structured the article under three headings to make it digestible and helpful, linking credible sources and my relevant articles if you are interested in details.

1 — An Overview of Adipose Tissues

Adipose tissues are connective and composed of adipocytes (fat cells). These cells store energy in the form of triglycerides.

Adipose tissues regulate energy balance and metabolism, providing cushioning and insulation for internal organs.

The beneficial and damaging aspects of different types of adipose tissue depend on factors like their location, distribution, and metabolic activities.

Adipose tissues are essential for metabolism and overall health. However, excessive adipose tissue accumulation in general, particularly in visceral or intramuscular locations, might contribute to cardio-metabolic disorders.

Adipose tissues are classified based on their functions and metabolic properties. The literature names them brown, beige, perivascular, epicardial, intramuscular, and visceral fats. Their dysregulation can contribute to various health conditions.

Brown adipose tissue is mainly found in babies with high mitochondria density having uncoupling protein-1 (UCP-1). As I documented in a previous article, we can increase brown fat with thermogenesis and intense workouts.

White adipose tissue stores energy in the form of triglycerides. It is the most abundant in the body. It is located under the skin as subcutaneous fat and around internal organs as visceral fat.

Beige is a mixture of white and brown. Thermogenesis through cold exposure can change the color of white to beige and later to brown with more intensity. They also include a bit of UCP-1.

Perivascular adipose tissue surrounds blood vessels. It regulates vascular tone and blood flow through the release of vasoactive substances.

Epicardial adipose tissue surrounds the heart. It is associated with an increased risk of cardiovascular disease due to its proximity to the coronary arteries and its production of inflammatory cytokines.

Intramuscular adipose tissue exists in skeletal muscle. It is linked to insulin resistance and impaired muscle function.

As I explained in previous articles, visceral fat is considered risky for health. It is associated with increased insulin resistance, hyperlipidemia, and chronic inflammation.

Excessive visceral fat accumulation in the abdomen can cause metabolic syndrome and other metabolic disorders like type II diabetes.

From an evolutionary perspective, the body stores fat in different ways. These patterns evolved as adaptations to different environmental pressures.

For example, subcutaneous fat might have evolved to store energy for times of scarcity, while visceral fat might have evolved to protect the organs from external threats and physical injuries.

2 — Comparison of Subcutaneous and Visceral Fats

Subcutaneous Fat

Subcutaneous fat refers to the fat stored beneath the skin. While sometimes associated with negative health outcomes, such as obesity and metabolic disorders, subcutaneous fat is essential.

Scientists are less concerned about subcutaneous fat than visceral fat for several reasons. Subcutaneous fat is an important and beneficial component of the body. However, it might also cause issues in large amounts.

For example, subcutaneous fat in the abdominal region is more metabolically active than in the hips and thighs. Therefore, higher amounts in the abdominal area are linked to the risk of metabolic disorders.

Fat cells in subcutaneous fat tissue can store excess energy as triglycerides, which the body can use during fasting or intense exercises. This is important for maintaining energy balance and preventing metabolic disorders such as insulin resistance and type II diabetes.

Subcutaneous fat can secrete adipokines, signaling molecules that help regulate inflammation and insulin sensitivity. Adipokines produced by subcutaneous fat, such as adiponectin, have anti-inflammatory and insulin-sensitizing effects.

Additionally, subcutaneous fat can be a physical barrier, protecting the body from mechanical stress and injury. It can also help regulate body temperature, as fat tissue is a good insulator.

Small amounts of subcutaneous fat are unlikely to cause significant inflammation. However, the literature indicates excessive subcutaneous fat accumulation can lead to chronic low-grade inflammation.

Subcutaneous fat can produce cytokines and other signaling molecules that can influence immune function and inflammation.

In people with excess subcutaneous fat, adipose tissue may produce higher levels of pro-inflammatory cytokines, contributing to chronic low-grade inflammation.

Visceral Fats

Visceral fat is stored around the organs in the abdominal cavity, like the liver, pancreas, and intestines. Visceral fat is more metabolically active than subcutaneous fat. It is believed to comprise around 10% of the overall body fat.

When visceral fat becomes excessive, it can release large amounts of free fatty acids and inflammatory cytokines into the bloodstream, impairing insulin sensitivity and leading to insulin resistance.

Visceral fat can cause hyperlipidemia. This can include high levels of triglycerides and LDL and low levels of HDL cholesterol.

Excessive visceral fat can lead to chronic low-grade inflammation linked to fatty liver disease, type 2 diabetes, cardiovascular disease, neurodegenerative disorders, and some cancers.

This paper provides a comprehensive overview of the current understanding of the pathophysiology of visceral obesity and the adverse health effects associated with this condition.

The authors highlight the importance of addressing visceral obesity as a key component of strategies to prevent and treat metabolic disorders.

Comparative Perspectives from the Literature

This paper shows differences between adipose tissue in subcutaneous areas and visceral adipose tissue in the abdominal cavity. These include anatomical, cellular, molecular, physiological, clinical, and prognostic differences. I summarize the key points.

“Visceral fat, compared with subcutaneous, is more cellular, vascular, and innervated. It contains more inflammatory and immune cells, lesser preadipocyte differentiating capacity, and a greater percentage of large adipocytes.

There are more glucocorticoid and androgen receptors in visceral fat than in subcutaneous. Visceral fat adipocytes are more metabolically active, more sensitive to lipolysis, and more insulin-resistant than subcutaneous adipocytes.

Visceral fat has a greater capacity to generate free fatty acids and to uptake glucose than subcutaneous. It is more sensitive to adrenergic stimulation. Subcutaneous fat is more avid in absorbing circulating free fatty acids and triglycerides. Visceral fat carries a greater prediction of mortality than subcutaneous.”

This 2013 paper informs, “Excess intra-abdominal adipose tissue accumulation (visceral obesity) is part of a phenotype for dysfunctional subcutaneous adipose tissue expansion and ectopic triglyceride storage closely related to clustering cardiometabolic risk factors.”

This 2020 review informs that “excess release of free fatty acids from adipose tissue lipolysis can account for a sizable portion of the metabolic complications of obesity. Upper-body subcutaneous adipose tissue accounts for most systemic free fatty acids, whereas visceral fat contributes a modest portion of the excess amount to which the liver is exposed.”

This 2022 paper states, “Dysfunctional visceral fat plays a key role in initiating and maintaining chronic inflammation, liver steatosis, and subsequent systemic insulin resistance that primes the body to develop the metabolic syndrome.”

I understand from the 2020 paper that subcutaneous and visceral fat might contribute to obesity. But I am more convinced by the 2022 paper discussing the effects of dysfunctional visceral fat.

Summary of Differences Between Subcutaneous and Visceral Fats

Subcutaneous fat is located beneath the skin. Visceral fat is deep within the abdomen surrounding internal organs. Both types of fat produce different hormones and cytokines.

Visceral fat is more metabolically active than subcutaneous fat. It produces higher levels of inflammatory cytokines. Subcutaneous fat produces higher adiponectin levels.

Subcutaneous fat has a higher metabolic rate than visceral fat. It can burn more calories. Visceral fat stores energy and can contribute to weight gain and metabolic disorders if it accumulates in excess.

Excessive visceral fat accumulation can lead to a higher risk of metabolic disorders due to insulin effect, blood lipid levels, and inflammation.

Subcutaneous fat is associated with a lower risk of metabolic disorders. This might depend on the location and distribution of subcutaneous fat in the body.

Unlike perceptions, the excessive accumulation of subcutaneous fat might also contribute to insulin resistance and inflammation.

3 — Hormonal Relationships of Fats

“Specific mechanisms for increased visceral fat storage when facing positive energy balance and weight gain may involve sex hormones, local cortisol production in abdominal adipose tissues, endocannabinoids, growth hormones, and dietary fructose.” [Source]

Different types of adipose tissue produce different hormones. The hormonal activity of different types of adipose tissue can have complex effects on metabolism and overall health.

Here’s a summary of key hormones related to different types of fats.

Leptin

This hormone regulates appetite and energy balance. It acts on the hypothalamus to reduce food intake and increase energy expenditure.

Leptin is primarily produced by white adipose tissue. However, small amounts of leptin can also be produced by other tissues, such as the placenta, stomach, and skeletal muscle.

The amount of leptin produced by adipose tissue is proportional to body fat. Therefore, leptin levels are higher in people with more body fat. However, leptin resistance makes this hormone dysfunctional.

I documented my experience with leptin resistance in a previous article titled Here’s How I Made My Body Leptin Sensitive and Stopped Food Cravings in 3 Steps.

Adiponectin

Adiponectin is primarily produced by adipose tissue, including white and brown adipose tissues. However, white adipose tissue is the main source of adiponectin in the body.

This hormone has anti-inflammatory and insulin-sensitizing effects. Adiponectin levels are lower in people with more visceral adipose tissue. Low adiponectin levels are associated with metabolic disorders.

You may check my research on adiponectin in an article titled Here’s Why Adiponectin Matters for Fat Loss and Inflammatory Health Conditions.

Resistin

There is an ongoing debate among scientists regarding the tissue-specific expression of resistin. It was initially thought to be produced by adipose tissue. Recent evidence suggests that other tissues, such as the liver and bone marrow, may also produce resistin.

Some studies suggest resistin expression is more prominent in non-adipose tissues than adipose tissue. It appears that resistin is not solely produced by adipose tissue but has a complex expression pattern in multiple tissues.

This review reports “resistin was shown in recent studies to play a key role in aging. High resistin levels induce insulin resistance and exert proinflammatory effects. Resistin has been shown to play a pivotal role in metabolic, inflammatory, and autoimmune diseases.”

This paper informs that “active research identified a significant role for resistin in stress biology and as a biomarker in diagnostics to evaluate disease status and treatment outcome.”

Fibroblast Growth Factor 21 (FGF21)

FGF21 is produced by brown adipose tissue. It has anti-obesity and anti-diabetic effects.

FGF21 levels are higher in people with more brown adipose tissue. Low levels of FGF21 are associated with metabolic disorders.

This paper informs that FGF21 regulates fatty acid oxidation in the liver and fatty acid metabolism in white adipose tissue. It has anti-inflammatory roles in the pancreas and cardiac muscles.

According to this paper in Nature, “FGF21 has been proposed as a therapeutic for metabolic complications.”

“The possible existence of obesity-related FGF21 resistance and endogenous FGF21 inactivation enzymes represent major obstacles to the clinical implementation of FGF21-based pharmacotherapies for metabolic diseases.”

Conclusions and Takeaways

All types of fats in adequate amounts are necessary for metabolic and hormonal purposes. Healthy lifestyle habits are vital to optimizing fat profiles in our bodies. Diet is the most critical one.

Eating adequate healthy fats does not make us fat. They are essential for hormonal function, energy metabolism, and neural health. Too much of anything can cause imbalances in the body. Dietary fat is no exception.

Dietary fats are dense in calories. Therefore, we should consume them in moderation. Balancing macronutrients for energy production is necessary.

I documented a case study related to this matter titled Here’s How Calories Caused Fat Gain for Arleth in a Keto Diet and How She Solved the Issue.

The second key point is that refined carbs (processed sugar) quickly become fat molecules if not timely burned and are stored as visceral fat in the abdominal area.

Therefore we must refrain from excessive refined carbs and sugar to prevent visceral fat accumulation, especially if we have a sedentary life. Very active people and athletes are more tolerant of carbs.

This brings us to the next important point. After the diet, the next critical point is exercise. Regular exercise is excellent for a better fat profile.

However, exercising two hours after main meals might quickly burn calories and prevent them from being converted to fat molecules for storage. Short exercise on an empty stomach might mobilize fat.

Excessive exercise without timely recovery can dysregulate the HPA axis, cause chronic stress, lead to elevated cortisol, and prevent fat burning from the abdominal area.

Thus stressed people cannot lose belly fat. It happened to me in my younger years, and I solved it and gained six-pack abs after my 50s.

More importantly, lowering white and increasing beige and brown fat can put us in a metabolically flexible and better-performing position. I discussed the details and provided practical tips in an article titled Reduce Visceral Fat and Increase Brown Fat with Two Practical Steps.

Thank you for reading my perspectives. I wish you a healthy and happy life.

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