Merely counting calories may not be good enough for those who have to watch what they eat.

Dietary requirements differ among patients with different medical conditions, said Dr Lim Su Lin, chief dietitian at the National University Hospital.

For example, diabetic patients have to watch their carbohydrate intake to avoid wide blood-glucose fluctuations, while those with hypertension, or high blood pressure, have to keep an eye on their sodium consumption.

This means that initiatives such as calorie labelling might need to be adapted to display additional nutritional information beyond how much energy the food contains.

The food calorie, or the kilocalorie (kcal), is a commonly used unit to measure food energy.

It is defined as the amount of energy required to raise one kilogram of water by 1 deg C.

"Calorie labelling may be a good start, but it is not a one-size-fits-all answer for chronic diseases," said Dr Lim.

Individual dietary requirements also vary depending on one's age, gender, weight and level of physical activity.

"It is important for patients who are keen on weight loss to understand the concept of energy balance," said Ms Wong Hui Mei, senior dietitian at Singapore General Hospital.

"Creating a caloric deficit or eating fewer calories than the body requires will eventually help with weight reduction."

Exercise is important when trying to create a caloric deficit and can help to improve cardiovascular fitness.

"Exercise and diet have to go hand in hand," said Ms Wong.

She added that finding the optimal combination of exercise and careful dieting is key for weight loss.

This is especially so for people in the high-risk range for chronic diseases as this is the group which has a body mass index of more than 27.5.

"It is essential for these people to seek evidence-based medical nutrition therapy from a dietitian," she said.

Lester Wong