How do wholegrains help to manage weight?

The higher fibre content of diets rich in wholegrains and legumes is one of the main mechanisms through which they help control body weight. Dietary fibre assists weight control in the following ways:

High-fibre foods are typically less energy dense (i.e. are lower in kilojoules / calories) than high-fat foods.
Fibre increases chewing, which increases saliva and gastric juice production. This expands the stomach and helps to satisfy appetite sooner.
The bulking properties of dietary fibre means it stays in the stomach longer, which produces an prolonged feeling of fullness.
Dietary fibre slows the absorption of energy and nutrients. This leads to lower blood glucose (blood sugar) and insulin levels after a meal, which promotes satiety (the satisfaction of appetite and feeling of fullness after eating).
High fibre foods typically have a lower glycaemic index (GI), which slows the rate of starch digestion. This response favours the breakdown of fat rather than its storage.
The findings of at least one study – the US Health Professionals Follow-Up Study3, involving over 27,000 men – suggest that there are additional metabolic effects beyond the effect of fibre content which assist weight control.

Wholegrains versus refined grains for weight control

Higher intakes of wholegrain cereals and legumes are consistently associated with a lower body mass index (BMI), waist circumference and overweight. One large study showed a slightly higher waist to hip ratio (WHR), but not BMI, with a higher consumption of refined grain foods. However, other studies have not supported this finding. The weight changes, although statistically significant, appear to be relatively minor (i.e. the refined grain study group had a weight gain of less than 0.7kg over a 12 year period)4.

Conclusion
The scientific evidence provides strong support for public health dietary messages to enjoy a wide variety of grain-based foods, particularly wholegrains and legumes, as part of a healthy diet in the quest to achieve and maintain a healthy weight. The totality of evidence available from research to date shows there is little evidence that a high consumption of grains increases the risk of obesity.

With respect to refined grains, the risk of obesity may be reduced by replacing refined cereal sources with more wholegrain, high-fibre and low GI grain foods, but further research is required to determine the absolute effect of such interventions.

For more detailed information on the scientific evidence supporting the role of wholegrains and legumes in weight management
MR.KAKAR