Sitting for most of the day could make us resistant to the usual metabolic benefits of exercise, according to a small but worrying new study. The findings, in the Journal of Applied Physiology, suggest that inactivity may alter our bodies in ways that are not just unhealthy on their own but also blunt the healthfulness of exercise.

We know, of course, that physical activity is good for us and being sedentary, for the most part, is not.

Regular exercise reduces the risk of heart disease, Type 2 diabetes and many other chronic conditions. Even a single workout can improve our metabolisms, studies show, so that we burn fat more efficiently after meals and keep our blood sugar and insulin levels steady.

Inactivity, meanwhile, has almost the opposite physiological effects. People who spend most of their waking hours sitting face heightened risks for many chronic diseases. They often also experience metabolic problems that raise the risk of diabetes and heart disease, including insulin resistance, poor blood sugar control and high levels of triglycerides, the fatty acids from food that linger in the blood if they are not metabolized.