It is common for my patients who have a high level of low-density lipoprotein (LDL) cholesterol, or "bad" cholesterol, to ask me if losing weight would help to reduce it.
This often triggers a discussion of what is considered fat and what losing fat helps to accomplish, besides getting a figure like Jennifer Aniston's.
There are a few ways to measure fatness. A commonly used one is the waist circumference in centimetres.
The National Heart, Lung, and Blood Institute in the United States defines the waist circumference at which the risk for diabetes, hypertension and coronary heart disease increases at 102cm for men and 88cm for women.
But the most commonly used and studied method is the body mass index (BMI). This is obtained by dividing the weight in kilograms with the square of the height in metres.
The World Health Organisation classifies someone with a BMI in the range of 25 to 29.9 as being overweight and a BMI of 30 and above as being obese.
In 2005, doctors lowered the BMI for being overweight to 23 for Asians, as Asians have a higher proportion of body fat and a higher incidence of diabetes at a relatively low BMI.
A higher BMI has been linked to a higher risk of death.
A landmark study by Dr Wei Zheng published in the New England Journal Of Medicine in 2011 followed 1.1 million Asians for an average of 9.2years and found that a BMI of more than 35 increased the chance of death by 50 per cent.
It has been documented that reducing weight leads to higher levels of high-density lipoprotein (HDL) cholesterol or "good" cholesterol.
It also lowers levels of blood pressure, blood sugar and triglycerides (energy-providing fat). It may also lower total cholesterol and LDL cholesterol levels.
This translates to less risk of diabetes and heart disease - good news for both the patient and nation.
However, the use of BMI is not without its critics.
Some patients with a high BMI do not look fat. In fact, their stomachs are flat enough to land an aircraft on.
This is because a person who has high bone or muscle mass also has a high BMI.
A study by Dr Katherine Flegal published in the Journal Of The American Medical Association this year caused another controversy.
It showed that a BMI of 25 to 35 was protective against all causes of death. The risk of death was increased by 29 per cent only when the BMI was above 35.
This means overweight and obese people were not at higher risk of death, but were actually at lower risk than those of normal weight. Only the severely obese were at higher risk.
My yardstick is whether the patient has other risk factors besides a high BMI above 25. I still use 25 as my guide as the study of Asians showed no increase in the risk of death up to this level.
For instance, my patient, John, 45, had a BMI of 28. He had a stocky build but did not look fat.
He smoked and drank alcohol.
His blood pressure, blood sugar and triglyceride levels were high, and his HDL cholesterol level was low.
An ultrasound scan also revealed a fatty liver.
He is considered to be at a higher risk of death due to all these metabolic abnormalities, which is called the metabolic syndrome.
Although he was only slightly overweight, he needed to lose weight - and stop smoking and drinking alcohol - to try to correct these abnormalities.
Another patient, Jane, 53, who complained of breathlessness, had a BMI of 34. Her fat was mainly gathered around the abdomen and waist, making her look pregnant.
Her blood pressure was normal, but her blood sugar and LDL cholesterol levels were raised.
Those metabolic changes made her a candidate for weight reduction.
Losing weight always looks like an impossible mountain to climb for those who are overweight, but it can be done.
The most cost-effective and safe strategy is to diet and exercise.
The goal is to lose about 10 per cent of weight in the first six months. This can be achieved by reducing caloric intake by 500 to 1,000 kilocalories a day.
Exercise will help prevent weight gain by burning extra calories.
I advise patients to walk more every day by taking 10,000 steps a day - equivalent to walking 8km or 30 minutes each day. Alternatively, they can do 30 minutes of brisk walking five times a week.
Walking is best as it is safer for overweight or obese individuals than more intense aerobic exercises.
A third patient, Sam, was one of those who succeeded. He had been overweight with a BMI of 30 and had mild hypertension, elevated blood sugar and high cholesterol.
He radically revamped his diet by cutting out all fat and carbohydrates and eating steamed fish, some lean meat and vegetables. He lost about 20kg. His blood pressure, blood sugar and cholesterol levels all became normal.
He has been able to keep up this regimen. That is the final key.
It is quite difficult to maintain weight loss over a long period of time. This takes a lot of discipline.
Patients have told me that life is not worth living if all delicious food is off-limits.
I suggest that they have a couple of days every month when they can eat anything they want. This makes it easier for them to stick to a weight-maintaining regimen.
Finally, I would ask: Have you seen any fat person among those who have appeared in the news as the longest-living man or woman?
Dr Kenneth Ng is a consultant cardiologist at the Novena Heart Centre. He specialises in treating heart failure. He was the director of the heart failure programme of the National Healthcare Group from 2003 to 2007.
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