We all know that excess weight is one of the key predictors of many common diseases, such as heart disease and diabetes. And yet, over the decades we notice that we have packed on 10, 20, or 50 pounds before we really noticed it. Why? Because the changes are gradual. No one wakes up ten pounds heavier the next day! We tend to gain one or two pounds per year, until suddenly we realize we have a problem.

While long-term weight gain is related to age and activity level, there are things you can do to prevent it.

Monitor the glycemic index of foods you eat. Foods with a high glycemic index are associated with weight gain. Foods such as white bread, soda, potatoes, baked goods, candy and so on have a high glycemic index. These foods cause your blood sugar to rise rapidly, triggering insulin release and fat storage. Consume fewer “simple carbs” and more “complex carbs”, proteins, and healthy fats.

Choose your proteins carefully. You might have heard that a diet high in protein can help prevent weight gain. But not all proteins are created equally! Studies have shown that protein from nuts, fish, and low-fat dairy are associated with weight loss, while protein from red meat and processed meats are linked with weight gain. As for eggs and cheese, they’re not necessarily bad unless you eat them along with a diet that is high on the glycemic index.

Exercise regularly. You knew we were going to say this. As we age, our activity level typically drops off, and that can lead to weight gain. Not only are you burning fewer calories; you’re also losing muscle mass, which boosts your metabolic rate. Remember to engage in some cardiovascular exercise to keep your heart healthy, but also work on keeping those muscles strong so that your metabolism won’t slump.

Buy a scale and use it. It’s normal for anyone’s weight to fluctuate up and down by a few pounds, and we certainly aren’t urging you to develop an obsession with weighing yourself every day. But keep a reliable scale in your bathroom and weigh yourself once per week, and adjust your diet and exercise routine accordingly. It’s easier to lose five pounds than it is to lose fifty!