​It’s a well-known fact: obesity increases your risk of chronic diseases such as type 2 diabetes.

However, this doesn’t mean that thinner people are unlikely to develop such conditions. In fact, even if you’re generally trim, you still need to watch out for an excess of visceral fat (belly fat), or fat around the internal organs.

Based on a local study, one in four healthy-weight Singapore Chinese in their 20s and 30s has low muscle mass combined with high body fat, and weaker bones.

Dr Ian Phoon, Senior Consultant from SingHealth Polyclinics, a member of the SingHealth group, explains more about this “thin outside, fat inside” phenomenon.

“Visceral fat is fat that you may not see, but accumulates around your organs. Visceral fat is more dangerous since it results in greater insulin resistance compared to sub-cutaneous fat, or fat under the skin,” says Dr Phoon.

Insulin resistance is when the body produces insulin, but is unable to properly use it to control blood sugar. Glucose (sugar) builds up in the blood, leading to diabetes.

Asians, especially South Asians, are genetically more prone to accumulating visceral fat (belly fat), compared to Caucasians. This is the unique “thin outside-fat inside” phenotype (body type).

Unhealthy lifestyles, such as a lack of exercise and eating foods high in calories (including soft drinks) and saturated fats (fried foods, fatty meats, lard, ghee, “junk” foods, etc.), also promote excess visceral fat.

Drinking alcohol frequently can also increase visceral fat, and it may manifest as a “beer belly”.

The Health Promotion Board recommends no more than two standard drinks per day for men, and women no more than one standard drink per day. A standard drink in Singapore contains about 10 grams of pure alcohol and is equivalent to one can (330ml) of regular beer, one small glass (100ml) of wine, or one nip (30-35ml) of spirits.

“Although men have lesser overall percentage body fat than women, they tend to accumulate their fat in the abdominal area, while women generally have more fat in their hips and thighs. However, women who have given birth or who have menopaused are more prone to fat in the abdomen than other women,” added Dr Phoon.

According to the MOH (Ministry of Health) National Health Survey of 2010, type 2 diabetes is most prevalent among Indians/South Asian (17.2 per cent), followed by Malays (16.6 per cent) and Chinese (9.7 per cent).

Regardless of race, your risk of type 2 diabetes tends to increase if you:

• Have a history of gestational diabetes (diabetes while you were pregnant)
  
  
• Have parents who are diabetic
  
  
• Take long-term oral steroids
  
  
• Are above 40 years of age
  
  
• Have pre-diabetes (your body has already started to become insulin-resistant but to a lesser extent than full-blown diabetes. This can be seen in your blood sugar test, which is higher than normal, but not as high as a diabetic.)

Apart from risk of type 2 diabetes, visceral fat is metabolically active, releasing fatty acids, inflammatory agents and hormones that lead to higher low-density lipoprotein (LDL) cholesterol, blood glucose and blood pressure.

This means that those with visceral fat are also at a higher risk of cardiovascular disease, dementia, certain cancers. 

Your BMI (body mass index) is a way to gauge your risk of type 2 diabetes. Generally speaking, the higher your BMI, the higher your risk of diabetes. The risk starts to increase from a BMI of 23 in Asians (25 for Caucasians).

However, the pitfall of using the BMI, says Dr Phoon, is that it does not distinguish between lean and fat mass. Thus if you do a lot of body-building, your BMI may be high without increasing your risk of type 2 diabetes.

There are two better ways to identify those with excess visceral fat:

1. The waist circumference (WC) or

2. The waist-hip ratio (WHR)

The following waist circumference (WC) measurements indicate an increased risk of diabetes and cardiovascular disease:

Source: International Diabetic Federation (IDF) 2006.

The formula for the waist-hip ratio (WHR) is as follows:

Waist-hip ratio (WHR) = Waist circumference ÷ Hip circumference

Regardless of race, a WHR > 0.9 in men and a WHR > 0.85 in women indicate an increased risk for diabetes, according to the World Health Organisation (WHO).

“A simpler way would be to take note if you can no longer fit into your pants! It may be a warning sign that your visceral fat is increasing,” says Dr Phoon.

The most effective way to reduce visceral fat is to eat healthy (follow the My Healthy Plate) and exercise regularly.

A healthy diet is one low in salt, saturated fats and oils, and high in fibre such as those in brown rice, wholemeal bread, fruits and le​afy vegetables. A well-balanced diet is not only helpful when it comes to weight loss. It also helps reduce the health risks associated with unnecessary weight gain. Avoid eating for the sake of it - stop eating if you don’t feel hungry.

Aerobics-type exercises (the kind that raises your heart rate and breathing rate) are especially helpful. Get at least 150 to 300 minutes of moderate-intensity aerobic activity per week. Also include at least 2 days of muscle-strengthening exercises as they benefit your bone and muscle health as well as contribute to better balance. You should also avoid or limit our alcohol consumption.

Stress can contribute to a growing waistline too, so get enough sleep and handle stress well through meditating or spending your time with friends and family to relax.

Ref: G25 (ed)

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