In the US, 40.3 percent of adults aged over 20 are now obese. Obesity increases the risk of many serious diseases, including heart disease, metabolic disorders (such as type 2 diabetes), and osteoarthritis. Obesity occurs as a result of an interplay of different factors, including (but not limited to) overeating and a lack of exercise. These factors result in more energy being taken in than is being expended, leading to excessive fat deposition. There are two types of fat found within our bodies – subcutaneous fat and visceral fat. Although subcutaneous fat is generally agreed to be the less harmful fat, both contribute to obesity and are associated with increasing the risk of developing certain diseases.
This article will discuss the differences between subcutaneous and visceral fats, the health risks associated with the different fats, and advice on how to manage fat levels for optimal health.
Subcutaneous fat is the layer of fat found just below the skin; it makes up approximately 90 percent of total body fat. Visceral fat makes up approximately 10 percent of total body fat. It is found surrounding internal organs beneath our abdominal muscles. Subcutaneous and visceral fats differ regarding function, metabolic properties, and association with health risks. Subcutaneous fat is generally considered the less harmful fat.
Unlike visceral fat, subcutaneous fat has biological roles within the body:
Despite these essential functions, excess subcutaneous fat can be harmful and lead to health concerns.
Due to subcutaneous fat’s energy-storing capacity, taking in too many calories and not expending enough energy results in an accumulation of subcutaneous fat and leads to obesity. The accumulation of subcutaneous fat can cause low-level chronic inflammation. This inflammation can be further exacerbated by adipocyte hypertrophy (fat cell expansion in size) in the subcutaneous fat of obese individuals. Low-level inflammation and, especially, adipocyte hypertrophy are strongly linked to the development of insulin resistance and type 2 diabetes.
The location of the subcutaneous fat is important, with high levels of abdominal fat strongly linked to insulin resistance, whereas high levels of thigh fat are associated with a decreased risk of unfavorable glucose levels. Localization is also important in the link between excess subcutaneous fat and an increased risk of developing heart disease. Abdominal fat is a strong predictor of atherosclerotic heart disease (a build-up of fats and cholesterol on artery walls) and mortality, whereas fat in the lower body (a high leg-to-total body fat ratio) is associated with decreased risk.
Excess subcutaneous fat, which results in obesity, can have detrimental effects on joint and bone health. Subcutaneous fat contributes to the increased body weight seen in obesity. As weight increases, the prevalence of knee, hip, and back pain increases due to joints having to cope with a higher load and, therefore, increased pressure. This joint pain may indicate the development of osteoarthritis (a joint disease that causes pain, stiffness, and difficulty moving). The link between osteoarthritis and obesity is strong, with one study showing that a 5 kg increase in weight increases the risk of knee osteoarthritis by 36 percent.
Chronic inflammation, caused by an excess of subcutaneous fat, can also contribute to the development and progression of osteoarthritis. The severity of osteoarthritis correlates with high levels of inflammatory proteins in the blood. The development of joint pain and osteoarthritis has a large impact on an individual’s quality of life, as it can lead to a severe lack of mobility.
In addition to impacts on physical health, a rise in subcutaneous fat levels can also have harmful effects on mental health. Research has shown that high and increasing weight is associated with lower self-esteem and being unhappy with appearance. This can lead to mental health disorders, including depression and anxiety. Conversely, low self-esteem increases the risk of weight gain and obesity, resulting in a vicious cycle. It is therefore important to incorporate body positivity into health promotions, centering an individual’s health (rather than appearance) into all advice.
Although subcutaneous fat does have negative effects on health, visceral fat is more directly linked to health risks. Visceral fat is more metabolically active than subcutaneous fat, leading to high inflammation, an increased risk of insulin resistance (leading to diabetes), and increased levels of cholesterol (leading to heart disease). Subcutaneous fat can also contribute to the development of these diseases; however, due to its less metabolically active status, a much larger quantity of subcutaneous fat is necessary for it to have these detrimental effects.
Simple measures of fat levels often include BMI (body mass index, an indicator of weight in relation to height), although this measure does not give any indication of different types of fat. Waist circumference measurements or waist-to-hip ratios can indicate visceral fat levels. A waist circumference of ≥35 inches in women and ≥39 inches in men or a waist-to-hip ratio of ≥0.8 in women and ≥0.9 in men suggest high visceral fat levels. Skinfold calipers can be used to measure subcutaneous fat levels. However, they tend to underestimate true levels, especially when used on the abdomen. The most accurate method of determining both subcutaneous and visceral fat levels is using magnetic resonance imaging (MRI) scans. The Ezra Blueprint MRI scan assesses body composition to analyze levels of visceral and subcutaneous fat, providing insight into your body.
Exercising regularly can make it easier to lose fat as excess energy is being burned. Some effective workouts to try include:
Consistency is key to losing fat and will result in gradual, healthy progress.
A further necessity for losing weight is achieving a negative energy balance (ie calorie intake should not exceed energy expenditure). You do not need to cut out foods or food groups, but high-calorie foods should be incorporated into your diet in a healthy way. Eating diets rich in whole foods, proteins, and healthy fats can be beneficial to helping you to stay full for longer and reducing cravings for high-fat or high-sugar foods.
Additional factors that play a role in weight loss include sleep and stress management. Sufficient sleep is necessary for appetite-regulating hormone balance, reducing calorie intake, and losing fat. Stress can also affect hormone balance, of particular note is its effect on increasing cortisol, which can result in an increased appetite and cravings, leading to a struggle to lose weight.
