After dinner each evening, do you usually plop down onto the couch and watch Grey’s Anatomy, The Voice, CSI, or sports on television? If that’s your daily habit, then it’s time to rethink your routine.

It’s not a healthy behavior for anyone, but for those with prediabetes (diagnosed as having a fasting glucose level of 100 to 125 mg/dL), who are dangerously close to developing type 2 diabetes (diagnosed as having a fasting glucose level of 125 mg/dL or higher), planting themselves in front of the tube is particularly risky.

A new study of 3,200 U.S. adults that was published this month in Diabetologia reveals that every hour that a person with prediabetes spends watching TV each day raises his or her risk of developing type 2 diabetes by 3.4 percent.

Why is sitting so harmful? There are a few reasons. For one thing, when you’re sedentary, you’re not moving your body much, and, therefore, you’re not burning many calories and it’s easier to gain weight (a risk factor for diabetes). Also, if you’re spending lots of time watching television, then you’re less likely to have time to exercise (which reduces your risk for diabetes). Finally, when you watch TV, you’re more inclined to snack, and when your mind is focused on the latest episode of The Big Bang Theory or Game of Thrones and not your food, you’re more likely to overeat, because you’re not paying attention.

So instead of watching TV for, say, two or three hours each night, try watching just one hour a night and spending the other hour going to the gym. Or buy a stationary bicycle and pedal while you watch at home. Or, at the very least, try doing some push-ups, crunches, or jumping jacks during the commercials of your favorite shows. Any strategy that helps you sit less and move more is a good one to try.

If you’re going to eat while you watch television, try having healthy snacks, such as carrot and celery sticks, raisins and nuts together, or Greek yogurt and berries, rather than unhealthy snacks like potato chips, ice cream, or cookies. If you can’t resist munching on something that’s bad for you, at least take one portion out of the package and put it on a plate or in a bowl before you walk into the TV room.

In my new book, The Gene Therapy Plan, I talk about the importance of physical activity and how eating nutritious foods can help ward off diabetes, as well as other serious health conditions, such as cancer, obesity, and heart disease. I explain that even if a disease like diabetes runs in your family, consuming certain foods can actually help switch certain genes “on” or “off” and reduce your chances of developing the disease. In fact, to make adopting healthy behaviors easier, I even provide numerous recipes and meal plans that you can follow to lose weight, lower your blood sugar, and feel your best. I’m happy to share that the book is now available at all major retailers and websites. I hope you’ll pick up a copy, so you can start achieving optimal health—today.