IN BRIEF: When it comes to nutrition, eating a pound of celery is not the same as eating a pound of chocolate cake. On its own, the weight of your meal isn't a meaningful guide. But weighing your food can be a practical way of managing portion size, if you combine it with a little knowledge.

Some researchers believe that increasing levels of obesity (a trend seen in many developed and developing countries) are largely caused by a gradual increase in food portion sizes since the 1970's.

One study published in the Journal of the American College of Nutrition measured how much breakfast cereal people served themselves and found:

Men served an average of 61g
Women served an average of 47g
The recommended serving was 30g (based on nutrient content and generally accepted nutritional guidelines)

In general terms, it makes sense that a bigger portion equates to more calories consumed. However, a plate of chips doesn't have the same nutritional value as a plate of vegetables, even if they weigh the same. Thus, portion control is more complicated than weighing your meal, it should include some knowledge of the nutritional content of different types of food.

Back to basics

At least half of your plate twice daily should be made up of salads and vegetables that you enjoy. The remaining half should be made up of equal portions of slow release (low GI) carbohydrates, unsaturated fats and lean protein.

Although this sounds easy enough, when you've been overdoing it for a long time, getting back to the right portion sizes may be difficult. Weighing your food types can be helpful initially. After some time, you will find that you can do away with the scale

If you need guidance on portion control, contact a dietician.