A study from Japan found that exercising in the late afternoon (4-6 PM) helps to control blood sugar, cholesterol and triglyceride levels better than exercising in the morning (9-11 AM) (Front Endocrinol, July 19, 2022).
Twelve healthy young men walked on a treadmill for one hour at 60 percent of their maximal oxygen uptake (VO2max) on Monday, Wednesday and Friday. They were tested during and after a week of exercising just in the morning or just in the afternoon. Blood sugar and fat control was much better in the afternoon exercisers.
• Continuous 24-hour monitoring of their blood sugar levels showed that total blood sugar levels were lower in the afternoon exercise time.
• Blood sugar levels after meals were lower after afternoon exercise. Most cell damage from high blood sugar comes from a high rise in blood sugar 1-2 hours after eating a meal.
• Triglyceride levels were lower after afternoon exercise. This is very important because your blood sugar level rises after you eat, and if it rises too high, sugar sticks to cell membranes and damages them. That’s why diabetes can damage every cell in your body. When your blood sugar level rises, your pancreas releases insulin to keep blood sugar levels from rising too high. Insulin lowers blood sugar by driving sugar from the bloodstream into the liver. However, if the liver is full of sugar, the liver does not accept more sugar and all the extra sugar is converted to fatty triglycerides. Having a blood triglyceride level greater than 150 usually means that your blood sugar rises too high after meals and you are already diabetic or prediabetic.
• Blood levels of the good HDL cholesterol were higher after afternoon exercise. When triglycerides rise too high, you are at increased risk for clots. To protect you from a high rise in triglycerides, your good HDL cholesterol carries the triglycerides from your bloodstream into your liver, so a high rise in triglycerides causes a drop in blood levels of the good HDL cholesterol. The lower your good HDL, the more likely you are to suffer a heart attack….