Are you TOFI?


Coronal image of a TOFI subject (left) with 5.86 l of internal fat, and a Normal Control subject (right) with 1.65 l.

A new buzzword is making waves in news and the healthcare community – “TOFI”, a term you’re sure to come across if you haven’t already.

The acronym TOFI[1][2] “thin-outside-fat-inside” is used to describe individuals who appear lean but actually have a disproportionate amount of internal fat (adipose tissue) stored within their abdomen, also called “VAT” visceral adipose tissue.  This is distinct from subcutaneous fat which is found under the skin.  VAT is found internally and also surrounds internal organs such as the liver.  Persons defined as TOFI have increased levels of risk factors associated with “metabolic syndrome”, the cluster of symptoms consisting of increased blood pressure, high blood sugar level, excess body fat around the waist (VAT), and elevated cholesterol levels.  Current statistics for this condition are not fully developed yet, but research to date performed on individuals with BMI’s between 20 and 25 found the instance of TOFI in the control group to be 14% of the men and 12% of the women[1].

TOFI classification is a further refinement of the “metabolically-obese but normal-weight” (MONW)[3][4][5] category, another acronym that does a good job pointing to the surprising fact that a person can appear fit yet actually be at health risk due to the effects associated with excessive internal fat.

To illustrate this, the Coronal scan image on the left shows two men, both 35 years old and each with a BMI of 25. Despite their very similar size, the TOFI subject (left side in red colors) had 5.86 liters of internal fat, while the healthy control subject (right side) had only 1.65 liters.

Persons with TOFI are described as being at higher risk of developing insulin resistance and type II diabetes due to the fact that they have reduced physical activity/VO2max, reduced insulin sensitivity, and higher abdominal VAT.  Another important characteristic is excessive levels of liver fat.

Larger statistical sets of data in regard to the prevalence of TOFI from a public health perspective are certainly in the works, but large scale data has been slow to develop.  This is because the classification of a person as TOFI is based on measuring internal fat, performed by MRI or CT scan methods, which are both time-consuming and expensive.  Waist circumference by itself is not sufficient, in that persons with identical waist measurements can have vastly differing amounts of internal fat.

In response to this health challenge and the clinical need for accurate diagnostics, seca’s introduced ground-breaking body composition technology, medically-validated to the MRI method, for the measurement of VAT using bioimpedance analysis (BIA).  Our pioneering device, the seca mBCA body composition analyzer, produces the closest medically-validated correlation to MRI for the measurement of VAT of any BIA device on the market.

It turns out there is more to internal fat than meets the eye.  Scientists are beginning to think of fat as an organ in the way that it produces chemicals and hormones.  Fat cells are sort of like “chemical factories” producing other substances which can cause health problems long-term, contributing to diabetes, heart disease, high blood pressure, strokes and other illnesses, including some cancers. As you put on more weight, the internal fat cells grow bigger, sending out chemical “messages” to nearby cells which start to divide to produce more fat cells.  A lean adult is estimated to have somewhere around 40 billion fat cells, an obese person two to three times more.  The first step to addressing TOFI is accurately measuring what’s there, and possibly tracking progress of internal fat and/or specifically VAT reduction by means of accurate BIA analysis combined with a supervised medical weight loss program.


1. Thomas, E. Louise; Frost, Gary; Taylor-Robinson, Simon D.; Bell, Jimmy D. (2012). “Excess body fat in obese and normal-weight subjects”. Nutrition Research Reviews 25 (1): 150–161. doi:10.1017/S0954422412000054. PMID 22625426.

2. Jump up ^ Thomas, E. Louise; Parkinson, James R.; Frost, Gary S.; Goldstone, Anthony P.; Doré, Caroline J.; McCarthy, John P.; Collins, Adam L.; Fitzpatrick, Julie A.; Durighel, Giuliana; Taylor-Robinson, Simon D.; Bell, Jimmy D. (2011). “The Missing Risk: MRI and MRS Phenotyping of Abdominal Adiposity and Ectopic Fat”. Obesity 20 (1): 76–87. doi:10.1038/oby.2011.142. PMID 21660078.

3. Ruderman Neil B.; Schneider, S. H.; Berchtold, P. (August 1981). “The “metabolically-obese,” normal-weight individual”. American Journal of Clinical Nutrition 34 (8): 1617–1621.

4. Jump up^ Conus, Florence; Rabasa-Lhoret, Rémi; Péronnet, François (2007). “Characteristics of metabolically obese normal-weight (MONW) subjects”.Applied Physiology, Nutrition, and Metabolism 32 (6): 4–12.doi:10.1139/H07-926. PMID 17332780.

5. Jump up^ De Lorenzo, A.; Martinoli, R.; Vaia, F.; Di Renzo, L. (December 2006). “Normal weight obese (NWO) women: an evaluation of a candidate new syndrome”. Nutrition, Metabolism & Cardiovascular Diseases 16 (8): 513–523. doi:10.1016/j.numecd.2005.10.010. PMID 17126766

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