Harvard investigators have turned up new and surprising information on why most of us keep putting on weight and what to do about it. They found that exercise and calorie counting aren’t enough.
The huge study involved 120,877 U.S. men and women who were healthy and not obese at the start of the study in 1986. For 12 to 20 years, they were checked every four years for weight and lifestyle factors. They kept detailed diaries about what they ate and how they lived.
Surprisingly, this healthy American cross-section gained an average of 3.35 pounds every four years. In 20 years, the average weight gain was nearly 17 pounds.
What caused the steady increase was not just the calories consumed but which calories, together with such lifestyle factors as smoking, watching television and hours of sleep.
French fries and potato chips, as could have been expected, led the list of bad foods — those that figured in regular weight gain. Others included red meats, processed meats, sugar-sweetened beverages, refined flour and other grains and sweets and desserts. The investigators noted that a large baked potato contains 278 calories, compared with 500 to 600 calories for a large serving of french fries.
On the good list — those that tended to promote weight loss — the surprising leader was yogurt. The puzzled investigators suspected that changes in colonic bacteria or some “unmeasured confounding factor” might have curtailed weight gain. Healthful vegetables, nuts, fruits and whole grains brought less weight gain even when consumption increased, possibly because they took the place of other higher-calorie and more highly processed food. High fiber content and slower digestion of fruits and vegetables helped this displacement.
Oddly, choosing skim or low-fat milk over whole milk made little or no difference in weight gain. Previous studies have shown that peanut butter can help people lose weight and keep it off, probably because it satisfies hunger.
As for alcohol, the study showed that women who drank a glass of wine a day were among those who gained the least weight. Other alcoholic drinks added to weight gain.
Persons who quit smoking sharply gained weight at first but later put it on more slowly. Continued smoking brought weight loss, possibly through undiagnosed chronic disease.
Sleep habits showed an unusual pattern. Weight gain was lowest among those who slept 6 to 8 hours a night and higher for those who slept less or more than that.
Television watching accompanied weight gain, possibly because it is sedentary and possibly because of snacking and influence on food choices.
The study provides helpful advice on help to stem the steady weight gain that means ill health for many Americans. The overall message seems to be to continue exercising but eat wisely and in moderation.