Food choices matter in weight control

Potatoes, sugary soft drinks among biggest sources of added pounds

If there was ever any suggestion that French fries are good for you, it’s now dispelled in stark detail. An analysis of data from three lengthy surveys that assigns actual pounds of weight gain to foods finds that fries, sodas and several other guilty pleasures are among the most potent waist expanders.

On the bright side, researchers attribute weight loss to eating yogurt, fruit, nuts and vegetables. The report appears in the June 23 New England Journal of Medicine.

“Conventional wisdom often recommends ‘everything in moderation’ with a focus only on total calories consumed, rather than the quality of what is consumed,” says study coauthor Dariush Mozaffarian, a cardiologist at Harvard Medical School and Brigham and Women’s Hospital in Boston. “Our results demonstrate that the quality of the diet — the types of foods and beverages that one consumes — are strongly linked to weight gain.”

Mozaffarian and his colleagues combined data from three long-term surveys conducted between 1986 and 2006 that included more than 22,000 men and nearly 100,000 women. The weight, diet and lifestyle information collected in those surveys enabled the researchers to calculate an effect for specific foods.

None of the participants was obese or had any serious medical problems at the study’s outset, and no one was asked to go on a diet. Starting with each volunteer’s weight at the outset, the researchers monitored any gain or loss at four-year intervals. On average, participants had gained 3.35 pounds at each four-year point. 

Potatoes stood out as a culprit. A single-serving bag of potato chips added to one’s daily intake tacked on 1.69 pounds over four years by this calculation. Potatoes prepared as boiled, mashed or baked, added about half a pound, while French fries larded on 3.35 pounds. A single sugar-containing soft drink per day tacked on 1 pound every four years. Butter, refined grains, desserts, processed or red meats, fruit juice, fried food or foods containing trans fats added somewhat less weight.

Other foods seemed to lower weight. Adding a daily serving of yogurt knocked off nearly a pound over four years, while adding a serving of nuts or fruit was associated with a loss of about half a pound each. An extra serving of whole grains, vegetables or diet soft drinks reduced weight slightly.

Changes in intake of dairy products other than butter and yogurt, whether low-fat or not, appeared to have little effect on weight.

A pound here and a pound there might not seem worth worrying about, but weight gain in middle age is often so gradual that people don’t notice it until they have already gained a substantial amount, Mozaffarian says. “These ‘small amounts’ are exactly what is causing the obesity epidemic,” he says.

Specifying which foods may lessen or prevent weight gain is highly practical, says nutrition scientist Christopher Gardner of Stanford University, who wasn’t involved in this study. “When you choose one of these foods, you choose not to consume something else,” he says. The strength of the study, he says, is that it demonstrates that “these are achievable differences because real, live people did them.”

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