Stay away from white bread, other 'high-glycemic' carbs, researchers say
THURSDAY, April 23 (HealthDay News) -- The type of calories you take in before a workout may influence how many calories you burn during your workout, new research suggests.
Women who ate a breakfast rich in carbohydrates that do not cause a spike in blood sugar -- think muesli, yogurt, skimmed milk -- burned 50 percent more fat during a post-breakfast workout than did those who ate a breakfast rich in the kind of carbohydrates known to make blood sugar rise sharply, such as cornflakes and white bread.
Carbs that cause a sharp blood sugar rise are known as high-glycemic index carbs, while those that don't are called low-glycemic index carbs.
While other researchers have also found that a low-glycemic menu is beneficial to fat-burning, the new study has some unique points, noted lead author Emma Stevenson, a senior lecturer at Northumbria University, Newcastle Upon Tyne, U.K. She conducted the study while at the University of Nottingham.
"Most of the research in the effects of the glycemic load of pre-exercise feeding has been carried out in male subjects," Stevenson said. Most of it also has focused on endurance athletes, which doesn't describe the bulk of the population.
Instead, the new study included eight women of a typical healthy weight who averaged 24 years of age. On two different occasions, the women ate either a high- or the low-glycemic index breakfast, then walked on a treadmill for 60 minutes three hours later. Stevenson's group drew blood samples before the breakfast and also during and after the exercise to measure parameters such as free fatty acids, which are a marker for fat burning.
The average amount of fat oxidized during the exercise was 7.4 grams after the low-glycemic meal but just 3.7 grams the higher glycemic index meal, a nearly 50 percent difference.
Why the disparity? High-
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