The Singapore Sports Council's head of sports nutrition, Png Weileen, offers some tips:

• Always compare the nutritional values of bars based on their net weight.

For example, both a 20g and 40g bar may provide the same amount of calories. The calories from the lighter bar could be due to a higher percentage of fat, which has nine calories per gram compared to four calories for each gram of carbohydrate and protein.

Dietary guidelines recommend that no more than 30 per cent of the caloric intake should come from fat.

• Do not be fooled by claims such as 'light', 'cholesterol free', 'reduced fat' or 'low carb'.

For example, vegetable oils such as palm oil or coconut oil may not contain cholesterol, but are high in artery-clogging saturated fat.

Some 'low carb' bars do not count fibre or sugar alcohols as carbs but, as Png puts it: 'Carbs are carbs.'

And '80 per cent fat-free' may sound great, but if the remaining 20 per cent is all fat, it is still a high-fat food.

• Generally, depending on the type and intensity of exercise, research has shown that athletes need to consume 30-60g (or about 0.5-1g per kg of body mass) of rapidly absorbed carbs each hour of exercise.

Go for a bar that is high in carbs and low in fat, protein and fibre, because carbs are the body's main fuel source.

Fat prevents the absorption of carbs, and fibre may cause gastro-intestinal distress as it is difficult to digest, especially during high-intensity activity.

Protein, however, is essential for recovery and muscle repair after exercise.

• Low GI (Glycemic Index) carb foods like whole grains and vegetables - that produce only small fluctuations in blood- sugar levels - are great for weight-loss as they keep you satisfied for longer.

But, for racing, aim to consume high GI carb foods, like simple sugars and white bread, which give the quickest blood-sugar and energy boost.

This article was first published in The Straits Times on November 22, 2008.