Blood Sugar Levels Affected by Activity

How foods affect blood-sugar levels varies from person to person and from one time to another in a single individual. For example, if you eat a jelly donut in the evening, your blood sugar may rise well over 200 (it should never be higher than 160). If you eat the jelly donut when you have been riding your bike for an hour, your blood sugar level may not rise at all.

Researchers at University Medical Center in Utrecht, the Netherlands showed that eating sugar and flour markedly increases risk for heart attacks in middle-aged women. Being overweight increased the risk even more. More than 15,000 healthy Dutch women, ages 49-70, were followed for nine years. They suffered 556 cases of coronary heart disease and 243 strokes. The ones most likely to be afflicted were overweight women who ate a diet high in foods that cause a high rise in blood sugar. Journal reference

The only places that you can store sugar in your body are your liver and muscles. If you eat lots of sugar or flour when your muscles are full of sugar, sugar goes from your intestines, into your bloodstream and then can spike to high levels. However, during or after prolonged exercise, sugar goes from your intestines into your bloodstream and then directly into your muscles, so it does not spike. For diabetics or overweight people, the safest time to eat foods that cause a high rise in blood sugar is while they are exercising. More on glycemic load of foods; refined carbohydrates; preventing diabetes