The Harvard School of Public Health (HSPH) conducted three separate studies and found that modest lifestyle and diet changes can lead to long-term weight gain. Prior studies have focused on weight loss after a person has already become obese, but this study aimed to determine what factors contribute to long-term weight gain.
The researchers monitored changes in multiple lifestyle factors and weight gain every four years over 12 to 20 years of three groups, the Nurses’ Health Study (NHS), the Nurses’ Health Study II (NHS II), and the Health Professionals Follow-up Study (HPFS).
They found that on average each participant gained 3.35 pounds in each three-year period. The foods associated with the highest amount of weight gain over the 20-year period were potato chips, (one increased daily serving equaled an extra pound and a half of weight gained in the 4-year period), other potato products, sugary drinks and meat.
They also found that sleep, television watching and lack of physical activity all contributed to weight gain. The National Institute of Health reports that almost 40 percent of Americans are overweight.