My Waistline

Did you know that not every overweight or obese individual is at increased risk of diabetes and heart disease? Many studies conducted over the last 30 years have shown that too much abdominal fat (the fat located in your abdomen) increases the risk of diabetes and heart disease whether you are obese or have a normal body weight. This is because abdominal (belly) fat behaves differently than the fat in your hips and thighs. Hip and thigh fat is designed to store energy derived from food, protecting the other tissues and organs, while abdominal fat is very active and releases fats and other substances that disrupt numerous body functions. If you have too much fat in your abdominal cavity (this is often described as having excess intra-abdominal fat or visceral fat), you may have a normal body weight but be “viscerally” obese and thus at high risk of diabetes or heart disease.

Why is visceral fat bad for your health? First, this fat behaves differently than the subcutaneous (under your skin) fat located in your hips and thighs. It releases fat molecules into the blood that accumulate in other tissues such as your liver, your heart, and your muscles, impairing their normal function. Second, visceral fat is loaded with cells (macrophages) that play a role in inflammation and release numerous substances (called adipokines) that increase your risk of diabetes and heart disease. Third, it has also been suggested that too much belly fat is a sign that your body does not store excess energy from your diet in its proper location (i.e., subcutaneously). This causes fat to build up at undesirable locations (such as your liver, your heart, and your muscles) leading to a range of health problems. Thus, abdominal obesity, particularly visceral obesity, is a frequent cause of complications such as type 2 diabetes, cardiovascular disease, atherogenic dyslipidemias (disorders in the transport of fat and cholesterol in the blood), liver steatosis (fat accumulation in the liver), sleep apnea and some forms of cancers. Recent studies have also linked excess visceral fat to impaired brain health such as reduced cognitive function and dementia. Because you can have a normal body weight and still have too much visceral fat, physicians and health professionals worldwide must take action to assess this new, hidden risk factor, which has been called the “cholesterol of the 21st century.”

On this webpage, the International Chair on Cardiometabolic Risk provides a step-by-step video on how to self-measure your waist circumference. Many studies have shown that measuring waist circumference is the best and simplest way to estimate how much abdominal fat you have. However, you have to know how to interpret the measurement results in order to determine whether they indicate high-risk abdominal obesity. Based on the relationship with body mass index (BMI) threshold values for overweight (25 kg/m²) or obesity (30 kg/m²), organizations such as the National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III) have proposed waist circumference values of 102 cm for men and 88 cm for women [1]. These values correspond to a BMI of 30 kg/m² defining obesity. However, interpretation of BMI is limited as it cannot be used to establish valid waist cutoffs to predict potential additional risk. Furthermore, age and ethnicity affect the relationship of waist circumference to visceral fat and related health risk. For instance, we know that Asians are more prone to diabetes for a given waistline. This phenomenon may be partly due to the fact that Asians are more likely to store visceral fat than Caucasians at lower BMI values. In addition, African-Americans are more likely to store fat subcutaneously than Caucasians. A single cutoff of 102 cm in men and 88 cm in women may therefore be unsuitable to define excess abdominal fat in all populations worldwide.

An International Diabetes Federation (IDF) committee on the metabolic syndrome attempted to address this problem in its 2005 guidelines [2]. Table 1 summarizes IDF waist circumference values according to ethnicity and sex. However, these values have not been validated against “hard” clinical outcomes and therefore provide “ballpark” figures to patients and their treating physicians.

This table has been endorsed by the Canadian guidelines on obesity, which have also emphasized that waist measurement is a vital sign that needs to be assessed in clinical practice [3]. However, as previously mentioned, men and women as well as various populations differ in their predisposition to store abdominal fat and in its relationship with diseases. Waist circumference values used to define abdominal obesity should therefore be sex- and population-specific.

[1] Executive Summary of The Third Report of The National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, And Treatment of High Blood Cholesterol In Adults (Adult Treatment Panel III). JAMA 2001; 285: 2486-97.
[2] Alberti KG, Zimmet P and Shaw J. The metabolic syndrome–a new worldwide definition. Lancet 2005; 366: 1059-62.
[3] Lau DC, Douketis JD, Morrison KM, et al. 2006 Canadian clinical practice guidelines on the management and prevention of obesity in adults and children [summary]. CMAJ 2007; 176: S1-13.

If your waistline is below the values presented in Table 1, you are probably not abdominally obese and do not have this emerging risk factor for diabetes and cardiovascular disease. However, if your waistline is above values for your sex and ethnic group, you should contact your physician for a proper assessment of your risk factors and overall health.

If your waistline is above values presented in Table 1, this does not automatically mean that you are abdominally obese. Your doctor will evaluate your global health and run simple tests to verify whether you have abnormalities commonly called the metabolic syndrome (Table 2). The metabolic syndrome is most often caused by a diet of overall poor nutritional quality and a sedentary lifestyle that lead to abdominal fat accumulation and insulin resistance (the cells of your body do not respond normally to insulin). You cannot diagnose the metabolic syndrome by yourself. So if you think that your waistline puts you at risk, please see your physician. Prevention is key. Invest in your health!

If you are diagnosed with excess abdominal fat and the metabolic syndrome, improving the overall quality of your diet and increasing your level of physical activity/exercise are the cornerstones of the treatment. Measuring waist circumference also provides a good indicator of the amount of abdominal fat loss in response to healthy eating and increased physical activity. In fact, some sedentary individuals with abdominal obesity may lose abdominal fat and increase their muscle mass through healthy nutrition/physical activity without necessarily losing weight! Losing waist without losing weight is not uncommon among individuals who take steps to change their sedentary lifestyle by incorporating regular physical activity/exercise. In this regard, several sections of our website provide basic tips to help you be more active and eat better. Regular physical activity is probably the best “polypill” available to reduce your risk of diabetes, heart disease, and other chronic diseases. If you think that your waistline is high, see your doctor, take action to invest in your health and quality of life and stay tuned to the International Chair on Cardiometabolic Risk website!