Cornflakes? Meusli? Coffee and Toast? Does it really matter?
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Researchers at the Northumbria University, Newcastle Upon Tyne have found that the type of carbohydrate you eat before your morning cardio session can affect the amount of fat you burn.
A study of 8 women aged around 24 years showed that by eating a low GI breakfast; think meusli, yougurt and skim milk; before an exercise session, the women used up 50% more fat than those who ate a breakfast that was high in the type of carbohydrates that make blood sugar levels rise sharply, such as white bread or cornflakes.
Most studies done on pre-exercise feeding and glycemic load have been done on men and usually with endurance athletes who have special exercise needs whereas this study gives results useful to the general population.
For the study, on two different occasions the women walked on a treadmill for 60 minutes three hours after eating either a high or low glycemic index breakfast. Blood samples were taken before, during and after the exercise, results showing the average amount of fat oxidized during the exercise was 7.4 grams after the low-glycemic meal but just 3.7 grams after the higher glycemic index meal, a nearly 50 percent difference.
Previous studies have shown that a low-glycemic menu before exercise is beneficial to fat burn but this study shows some additional results. The caloric value of the breakfasts was always 265 calories but the low GI option had a higher fibre content. We know that high glycemic carbs cause a rapid spike in blood sugar levels while lower GI carbs cause a lower blood sugar response and this may boost the body’s use of bodyfat for cardio exercise energy.
This study builds on previous results and although it used women of healthy weight it’s anticipated that the results hold true for those needing to lose some weight. Low GI breakfast foods include whole grains, porridge, some whole grain cereals, soy and linseed bread. Portion size remains important; eating a large amount of low GI carbs before exercise would be detrimental to both regular and overweight exercisers.
