Researchers at Harvard University conducted a 20-year study that confirmed what you probably already knew: If you consume potato chips, sugary drinks, and red meat—even in moderation—on a regular basis, you’re going to gain weight. What makes the study interesting is that it tracked exactly which foods cause long-term weight gain, and, down to decimal-point accuracy, exactly how much they contribute.
Published this week in the New England Journal of Medicine, the study looked at data from over 120,000 men and women who participated in government-funded surveys beginning in the 1970s. They were able to mine data from as far back as 1986, the first year for which detailed information on diet, physical activity, and smoking habits were available. Then they analyzed the participants’ progress every four years, tracking weight gain and looking for lifestyle choices that might influence it, including how much television they reported watching, how much sleep they got, what they ate, and how active they were.
Their findings? Participants gained an average of 3.35 pounds every four years. The biggest culprit was potato chips, which accounted for 1.69 pounds for those who ate them every day. Potatoes (1.28 pounds), sugary drinks (1 pound), and unprocessed red meat (.95 pounds), such as slabs of beef, pork, or lamb, also made the list. Perhaps not surprisingly, participants who daily ate vegetables, whole grains, fruits, nuts, and yogurt gained less weight.
Researchers also analyzed lifestyle factors. Regular television watchers gained .31 pounds per hour of TV viewing a day. Those who got less than six or more than eight hours of sleep a night saw more weight gain, and daily alcohol intake contributed .41 pounds per drink per day. On the flip side, physically active participants gained 1.76 fewer pounds than their more sedentary counterparts.
The takeaways from this study are pretty obvious: If you want to avoid long-term weight gain, follow your instincts, and practice eating and lifestyle habits you probably already know you should be doing. Start with watching less TV, and don’t eat while you do it. Eat a cup of yogurt topped with chopped nuts as an afternoon snack. Need to eat more fruit? Try a breakfast smoothie. And if you want to start exercising more, start small—maybe 15 minutes a day—and build up from there.
The key is not to expect dramatic changes over night. Remember, the study looked at weight patterns over two decades, so this is more about long-term health than a crash diet.
For more tips and advice, check out these interviews with local nutritionists and trainers:
• Sure-Fire Snacks
• Heart-Healthy Nuts
• Smoothie Recipes to Keep You Full and Satisfied
• Health and fitness apps for your smartphone
• Practicing Good Heart-Health
• How to work out at the office and at home
• Restaurant Salads to Avoid