Exercising after a meal

STUDY: EXERCISING AFTER A MEAL CAN HELP BLOOD GLUCOSE MANAGEMENT

We know that raised blood glucose after eating – and accompanying insulin resistance – are red flags when it comes to your risk of developing type 2 diabetes. People with raised blood glucose levels can experience adverse health events prior to developing diabetes and tend to be more at risk of complications associated with type 2. The World Health Organisation has identified raised blood glucose as the leading risk of early death behind hypertension and tobacco use. A new study published in the Canadian Journal of Diabetes suggests that increasing levels of exercise can have a powerful, positive effect on glycaemic management and insulin sensitivity, both immediately and in the long term. The study shows that these benefits can also be enhanced by considering the timing and nutritional composition of meals around exercise.

Raised blood glucose after eating and insulin resistance are, initially, the result of decreased glucose uptake in peripheral tissues such as muscles. There is a genetic component, but it is more often explained by imbalanced nutrition or a lack of physical activity. When the muscles don’t absorb as much glucose, the pancreas produces more insulin to deal with it. Over time, without treatment, this increased amount of insulin isn’t enough, generally leading to a diagnosis of type 2 diabetes. Exercise is known to be a key part of the prevention and management of type 2 diabetes, partly because it reduces those post-eating glucose spikes. The new study attempted to establish the impact of different forms of exercise, comparing a single session (acute exercise) with repeated sessions (chronic exercise) and taking into account the efficacy and timing of the type of exercise. The study split the effects of exercise into three phases. The first examines the way in which exercise immediately lowers blood glucose levels. Exercise increases the body’s energy demand, which can increase muscle glucose uptake by 20 times. In adults with prediabetes or type 2, an overall reduction in blood glucose concentration is usually observed during exercise, especially if performed after eating. Available evidence suggests that exercise performed after eating prompts superior reductions in blood glucose levels. Many types of exercise are effective, including walking, resistance exercise, cycling or stair climbing, although higher exercise volumes lead to more consistent reductions.

The second phase concerns how exercise can improve how well insulin worksand glucose uptake by the muscles in the days following exercising. For example, walking for 60 minutes in the afternoon has been shown to improve insulin sensitivity the next morning in adults with obesity.

How and when you exercise can make a big difference to your blood glucose management.

More intense exercise has been shown to improve insulin sensitivity in healthy males for up to two days afterwards. The third phase looks at how repeated sessions of exercise cause changes in the body that improve blood glucose management. Exercise training is shown to result in changes that improve insulin effectiveness and glycaemic management in adults who were previously not exercising and in adults with prediabetes or type 2 diabetes. The intensity of this exercise had a notable effect on blood glucose management for people living with type 2 and it was important that the exercise was maintained to sustain the benefits – particularly for those who didn’t lose weight as a result of exercise. These repeated sessions were also shown to be most beneficial when performed after a meal – doing so provided more consistent improvements in blood glucose management for adults with type 2 diabetes. In conclusion, the study authors note that short- and longterm exercise provide a powerful stimulus to reduce high glucose levels after a meal. The improvements to blood glucose management brought about by exercise may be even more pronounced if exercise is performed after meals. Further research should help develop more effective recommendations around eating and exercise to help prevent and treat type 2 diabetes.