Evidence suggests that whole grains are beneficial in maintaining correct body weight. Whole grains appear to be beneficial in weight control because they aid appetite regulation through improved glycaemic control and increase short-chain fatty acid production in the colon. Whole grains are also a good source of vitamins and minerals. Generally, whole grain intake is inversely associated with weight gain over time. Much of the weight loss research on whole grains has centred on investigating effects on obese subjects. For example, in a randomised control trial involving 113 volunteers with a body mass index of over 28kg/m2, subjects were advised to consume 2 servings of pulses and 4 servings of whole grains a day for 18 months1 or follow a lower whole grain and pulse diet. Those in the high whole grain and pulse group increased fibre and micronutrient intake when compared to the control group.
In terms of weight loss, there was no statistical difference between groups, with the control group losing 6kg and the whole grain and pulse group losing 6.3kg. Blood pressure, triglycerides and glycaemic load decreased in both groups, possibly because of the weight loss. However, waist circumference at 18 months was decreased (-2.8cm) significantly in the treatment group compared to the control group, suggesting that abdominal obesity had been reduced. Interestingly, the treatment group had a significant decrease in glycaemic index in their diet compared to the control group. This may explain the reduced waist circumference. Higher glycaemic index diets tend to decrease insulin sensitivity through increased insulin secretion and the resulting insulin resistance is characterised by increased abdominal fat. These results support the contention that whole grain diets are beneficial for weight loss and prevent obesity if consumed long-term.
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