Though fad diets and new “miracle” techniques for weight loss are regularly touted in American popular culture, health professionals have consistently maintained that eating moderate portions and exercising regularly is the only sure way to ensure a trim waistline and good health. However, exactly what kinds of foods and lifestyles produce the best outcomes remains the subject of debate.

A 2011 study published in the New England Journal of Medicine, “Changes in Diet and Lifestyle and Long-Term Weight Gain in Women and Men,” looked at data from three studies that follow some 120,000 men and women in the United States over up to a 20-year period. The researchers analyzed four-year periods in participants’ lives and the factors that influenced outcomes. Study participants evaluated were adults under 65 who did not have significant complicating health problems.

The study’s findings include:

• Every four years, the average person gained 3.35 pounds, or 2.4% of body weight; this translates to an average weight gain of 16.8 pounds over a period of 20 years.
• Those with greater increases in physical activity gained 1.76 fewer pounds within each four-year period; however, absolute levels of activity were not associated with weight loss.
• Increases in consumption of certain foods had distinct associations with weight gain. For each of the following, an increase of one serving per day resulted in specific weight gains over a four-year period: french fries (3.35 pounds); potato chips (1.69 pounds); boiled, baked, or mashed potatoes (0.57 pounds); sugar-sweetened beverages (1 pound); unprocessed red meats (0.95 pounds); processed meats (0.93 pounds); refined grains (0.39 pounds); and sweets and desserts (0.41 pounds).
• Conversely, consumption of one more serving per day of certain other foods was associated with weight loss over a four-year period. These include: vegetables (-0.22 pounds); whole grains (-0.37 pounds); fruits (-0.49 pounds); nuts (-0.57 pounds); and yogurt (-0.82 pounds). These foods’ “inverse associations with weight gain suggest that the increase in their consumption reduced the intake of other foods to a greater (caloric) extent, decreasing the overall amount of energy consumed.”
• The mechanisms behind yogurt’s healthful impact are not certain: “Intriguing evidence suggests that changes in colonic bacteria might influence weight gain. It is also possible that there is an unmeasured confounding factor that tracks with yogurt consumption (e.g., people who change their yogurt consumption may have other weight-influencing behaviors that were not measured by our instruments).”
• Weight gain of 0.41 pounds was linked to each alcoholic drink per day consumed, though the type of drink and the level of change in consumption for the individual also affected this dynamic.
• Those getting less than 6 hours of sleep or more than 8 hours of sleep were likely to gain weight.
• For every hour a day of television watching, individuals were likely to gain 0.31 pounds.
• Those who quit smoking in the previous period gained an average of 5.17 pounds over a 4-year interval; continuing smoking was associated with a 0.7 pound weight loss over the same period.

Tags: obesity, nutrition