The global obesity crisis has traditionally been focused on body weight and body mass index (aka BMI) rather than body shape and composition. Weight and BMI are blunt tools that can identify more obvious health risks, but unfortunately they miss the more subtle manifestations of dangerous and often hidden visceral adipose tissue (aka “VAT”).
VAT, unlike subcutaneous adipose tissue (aka “SAT”), is actually quite hidden in particular ethnic groups like South Asians/Indians and East Asians. These are typically folks who come into our clinic looking quite slender with a normal or even low BMI, but metabolic testing typically reveals signs of hidden VAT such as high triglycerides, low HDL (good cholesterol), elevated liver function tests (sign of fatty liver), and elevated inflammatory markers like hsCRP (highly sensitive C-reactive protein). They typically have slender arms and legs and a slight to moderate protrusion in the belly region. Family members and friends call these patients “skinny” but clearly their labs indicate a different picture. They have excess VAT (hidden, inflammatory fat) and very little SAT (visible, subcutaneous fat).
Why is VAT Bad?
Unlike the more visible SAT which is composed of inert fat cells with no hormonal activity, the more covert VAT fat cells are biologically active and release hormones and chemicals that promote dangerous processes such as oxidation, inflammation, and coagulation (blood clotting), which are linked to every chronic health condition from diabetes and heart disease to cancer and Alzheimer’s disease. See the image below from my book which illustrates how belly fat (VAT) is a factory producing these disease-provoking substances. If you don’t understand insulin resistance and inflammation, type these words into the search box of my blog and read the related posts.
Key Point: VAT is visceral, inflammatory hidden fat not always obvious to the naked eye, while SAT is the more externally visible, less inflammatory subcutaneous fat.
Fat Compartments Defined with a Jelly Donut
Let’s look at these compartments in more detail among different ethnic groups. Pay attention to the diagram below and think of the different fat compartments (VAT and SAT) as being a jelly donut. The inflammatory VAT is the red jelly in the center. The SAT is the surrounding donut crust.
Notice how Caucasians have a moderate amount of SAT (donut crust) and VAT (jelly), African Americans have a larger proportion of SAT (donut crust) and a smaller amount of VAT (jelly) and Asians (East Asians, Indians, etc.) have a ton of jelly and just a small rim of donut crust. The VAT is stored deep inside their abdomen, surrounding their digestive organs and often infiltrating their liver. To emphasize, these are genetic tendencies and not hard and fast rules.
It is true that in my clinic for example, my Caucasian patients can get away with a higher BMI without adverse metabolic consequences because more of that fat mass is coming from SAT. They've got an increased donut-to-jelly ratio. My less fortunate Asian patients stroll in thinking weight is not an issue, but their metabolic numbers clearly indicate they are stashing away excess inflammatory VAT. They've got an increased jelly-to-donut ratio.
In my book, I also refer to this as the “Iceberg Effect” which is illustrated below. Most of the dangerous ship-sinking mass of an iceberg is located below the surface of the water. Similarly most of the dangerous inflammatory VAT mass is also lurking deep inside your belly. Hopefully the combination of the jelly donut and the iceberg analogies make it crystal clear that we cannot judge an individual’s risk, especially of Indian or Asian ethnicity, by looking at the surface. We need to dig deeper by looking at other biomarkers.
Men vs Women
There are also significant differences in how men and women compartmentalize body fat. Generally before menopause, women tend to store more SAT, while men have a greater overall tendency to accumulate VAT. After menopause this shifts and women start to accumulate more VAT which is one reason their cardiovascular risk also increases.
We definitely see this in the clinic, where premenopausal Indian women often come in with very high BMIs, but their biomarkers do not show any signs of insulin resistance or inflammation. This is a clue that they are carrying around excess SAT and minimal VAT. On the other hand, their spouses who I often see with them in clinic, have a much lower BMI, but their metabolic markers are through the roof despite looking “skinnier.”
Unfortunately over the last decade I'm seeing a shift in my clinic where a growing number of young, premenopausal women are now presenting with metabolic syndrome and greater VAT. Our current childhood obesity epidemic is planting the seeds for visceral adiposity much earlier in life so that this post-menopausal VAT tendency is now presenting prematurely. Other insulin resistant conditions like PCOS (polycystic ovarian syndrome) which is also linked to VAT, is also on the rise. If you don't know about PCOS, be sure to read about it here.
Key Point: The proportion of VAT and SAT in each individual is based on a variety of irreversible (genetics, ethnicity, sex) and reversible factors (nutrition, physical activity, stress, sleep).
Some Markers of Excess VAT
As we mentioned earlier, some typical metabolic markers that indicate you might be carrying around more VAT include measures such as elevated triglycerides, low HDL (good cholesterol), elevated ALT (liver inflammation test), and elevated hsCRP (marker for inflammation). Essentially the same markers that define insulin resistance and metabolic syndrome are also clues to VAT.
How to Measure VAT
Aside from doing body fat testing, which we can discuss in more detail in a future post, waist measurements are the preferred way to assess heart disease risk in individuals. The Interheart Study involving 27,000 participants across 52 countries showed waist-based measurements like the waist-to-hip ratio (WHR) are superior to measuring weight or BMI when assessing heart disease risk across multiple ethnic groups. This is an informative video on how to properly measure waist-to-hip ratios. You can also refer to the body size measurement page that I created for my medical group here. It also includes an Asian/Indian adjusted BMI calculator. I already mentioned that BMI is a rough tool, but if you are using it, you must adjust the normal range for Asians.
A BMI of 23 rather than 25 is the cutoff for Asians/Indians. Now you know why. Just a little excess weight has a greater tendency to deposit in the dangerous visceral region in these high risk ethnicities. In lower risk ethnic groups like Caucasians, more of the fat mass accumulates in the visible subcutaneous compartment before penetrating the deeper visceral layers. Like the gentleman below who has slender arms and legs, but an exaggerated protuberant belly. We call these individuals “skinny fat” which I write about extensively in my book and cover in this blog post for my medical group. Many of these patients do not have such obvious abdominal obesity.
Again, these are rough guidelines. I have definitely seen slender Caucasians with high VAT and very obese South Asians with much more SAT than VAT.
One fun way I tell individuals to assess their abdominal obesity is to stand up and look down at their feet. Assuming you are not born with disproportionately small or large feet, typically if you cannot see your feet at all, abdominal obesity is likely an issue. As you make the right lifestyle changes as I outline in my book, that belly will start to recede, and your feet will emerge from this aerial view. I’ve had patients come into my office beaming with pride, telling me they can actually see their ankles for the first time. Now that's a sign of progress!
The practice of identifying health risk based on individual body shapes and types is a more recent trend in Western medicine, but has been a fundamental part of assessing health status in the 5,000 year old science of Ayurveda, which originated in India. The 3 body types are illustrated below and each has its own unique characteristics which include temperament, dietary and exercise preferences.
Traditional Chinese medicine uses body types based on temperature, such as cold, hot or damp to define these same characteristics (temperament, diet, etc.). The wisdom of these ancient sciences is not to create one generic measurement like weight or BMI and stamp it on all human beings with pre-defined risk categories, but instead to acknowledge the subtle nuances of body shape and temperature to provide more personalized recommendations.
Based on the information in this blog, I urge you not to make snap judgements about people’s health based on their visible appearance. I see far too many slender Indians and Asians in my practice that have experienced a heart attack or are facing high risk conditions like diabetes and highly abnormal lipid profiles. Although I spent most of this post focusing on the dangers of excess abdominal fat (aka VAT), what I failed to mention is that there is a second dangerous component to this body habitus, which is a lack of adequate muscle mass in the arms and especially the legs. I’m starting to view that lack of muscle as being at least as important as the excess belly fat since we need sufficient muscle to burn carbohydrates and prevent insulin resistance as I explain in this post. This means skinny fat individuals need to really work on doing some form of regular resistance training involving large muscle groups such as legs and core. Think squats, lunges and full body engaging exercises like push-ups, planks and burpees which I outline in the exercise chapter of my book. Focus less on total weight and more on waistline and overall body composition as a critical measure of health risk. Fortunately awareness is spreading about the dangers of an expanding waistline due to resources such as www.myhealthywaist.org and a recent post at the blog, Desi Nutrition Authority (DNA).