Pulses are the edible seeds of legumes and can include beans, peas, chickpeas and lentils. Epidemiology suggests that diets high in pulses are associated with a lower risk of obesity and weight gain. Epidemiology also suggests that fibre is inversely associated with weight gain and obesity, and pulses are a good source of fibre. The mechanism by which fibre might be protective of weight gain is not known, but fibre can decrease appetite and glycaemia by slowing gastric emptying, and can undergo colonic fermentation to form short-chain fatty acids that can be used as a source of energy by the host. Pulses may therefore be protective of weight gain because of their fibre content. However, pulse consumption may be a marker for a higher quality diet and improved lifestyle factors. Therefore the association between pulses and protection from obesity may be explained by confounding variables.
To investigate the short-term mechanisms by which pulses may prevent obesity and weight gain, researchers1 fed young adult men (18 to 35 years; body mass index 20 to 25kg/m2) either canned navy beans, freshly cooked navy beans, or 300mL of glucose, each containing 50g of carbohydrate. In another experiment the same subjects were fed either canned navy beans and pork in tomato sauce, maple syrup and molasses, homemade navy beans and pork in molasses, or white bread, each containing 50g of carbohydrate. Finally the same subjects received either one of four isocaloric (300kcal) pulse meals (made with chick peas, navy beans, yellow peas or lentils), white bread or a water control. For up to 120 min post treatment, blood glucose and appetite were monitored, and a pizza meal was used to assess the effects of the pulses on subsequent food intake.
All treatments decreased appetite sensations in the subjects, but there was no significant difference between the pulses, glucose drink or white bread. There was also no significant difference between the control and treatment groups with respect food intake at the subsequent pizza meal. The glycaemic response to food was altered by the recipes containing the beans, but did not differ between canned and home cooked treatments. Pulses consumption resulted in lower postabsorptive glucose area under the curve compared to white bread and glucose. These results suggest that short term appetite and food intake is not effected by pulse consumption and this may therefore not be the mechanisms by which pulses protect from obesity. However, longer-term appetite may still be regulated by frequent pulse consumption, as may occur through the production of short-chain fatty acids by colonic fermentation of the fibre contained within the pulses.
RdB
