Exercising before or after eating helps to protect you from having a high rise in blood sugar after meals. Even light exercise before or after you eat can prevent a high rise in blood sugar and the damage it can cause (Topics in Clinical Nutrition, April/June, 2014;29(2):132-138).
Healthy college students had their blood sugar levels measured for two consecutive days:
• after fasting
• 30 minutes after eating a Milky Way candy bar containing 35 grams of sugar, and
• 60 minutes after eating the candy bar.
On the third day, they walked at an easy pace for 30 minutes after eating the candy bar. Without the mild exercise these apparently-healthy young people spiked high blood sugar levels after eating. With walking afterwards, their blood sugars did not rise very much at all. These findings should be used by everyone, not just by diabetics. High rises in blood sugar can damage every cell in your body.
How High Blood Sugar Damages Cells
Cells are like little balloons full of fluid. When blood sugar levels rise too high, the sugar can stick to the outer membranes of all types of cells in your body. Once stuck on the outer surface membrane of a cell, sugar can never get off. It is eventually converted by a series of chemical reactions to sorbitol which destroys the cell. This is what causes damage in diabetics and even in pre-diabetics (metabolic syndrome) and those who are not diabetic. The damage can include:
• heart attacks (Curr Mol Med, 2007;7(8):699–710)
• aging (Exp Gerontol, 2007;42(7):668–675)
• strokes (Proc Natl Acad Sci U S A, 1995;92(9):3744–3748)
• dementia (Neurobiol Aging, 2011;32(6):763–767)
• blood vessel damage (Circulation, 2006;114(6):597–605)
• impotence, mood disorders, osteoporosis, cartilage damage, blindness, deafness, and more.
No tissue is spared. Non-diabetics who have high rises in blood sugar after meals are at increased risk for many different cancers (Diabetologia, September 8, 2014). The more sugar that you eat, the higher the rise in blood sugar and the more sugar sticks to cells to damage them (J Am Coll Nutr, 2005;24(1):22–29).
How Exercise After Eating Prevents a High Rise in Blood Sugar
Resting muscles draw almost no sugar from your bloodstream and the little that they do draw requires insulin. Contracting muscles draw large amounts of sugar from the bloodstream and insulin is not required. This effect of contracting muscle during exercise pulling sugar from the bloodstream without needing insulin lasts only up to 17 hours after you finish exercising, so to gain this benefit you need to exercise every day. Exercising before or immediately after you eat gives the added benefit of helping to prevent the spike in blood sugar that follows a meal, particularly one that includes sugar-added foods.
Most North Americans suffer a high rise in blood sugar after meals, even if they are not diabetic. Eighty percent of manufactured foods contain added sugars. If you are not diabetic but are overweight, particularly if you store fat primarily in your belly and not your hips, you can expect to get a high rise in blood sugar after eating sugar-added foods or even refined carbohydrates such as pastas or cereals that contain no added sugars. Frequent high rises in blood sugar levels can cause diseases and shorten your life. You can help to prevent a high rise in blood sugar after meals:
• Try to exercise before or after your main meal
• Try to exercise every day
• Avoid sugared drinks and sugar-added foods
• Eat plenty of vegetables, whole fruits and seeds (nuts, beans and so forth)
• Do not lie down or go to sleep immediately after you eat
• Grow muscle
• Reduce body fat, particularly in your belly
• Avoid being overweight
• Get blood levels of hydroxy vitamin D levels above 50 nmol/L
• If you are overweight or store fat primarily in your belly, restrict all refined carbohydrates (foods made from flour such as most dry breakfast cereals, bakery products and pastas), even those that do not contain added sugars.