LINKÖPING, Sweden—Shoppers who took month-long vacations may be looking to reduce those travel pounds, but a new Swedish study finds overindulging for a short time period can make it more difficult to lose excess weight (Nutr Metab (Lond). 2010 Aug 25;7(1):68; doi:10.1186/1743-7075-7-68).
Researchers Asa Ernersson, Fredrik H Nystrom and Torbjorn Lindstrom from the Linköping University, found one year after subjects ate a month-long diet of fast food still had an increase of fat mass than they did before the study.
Eighteen subjects with a mean age 26 (+/- 6.6) years, increased their caloric load by about 70 percent, mostly from fast foods, so their average caloric intake was 5,750 calories per day. They also reduced their physical activity; they were not to exceed 5,000 steps per day, which is typical of a sedentary lifestyle. Body composition was measured at baseline, after the intervention and after 12 months. A matched control group was also included. After the month-long intervention diet, subjects reduced to their previous diets and exercise routines.
After the month of unhealthy eating, body weight increased an average of 6.4 (+/- 2.8) kg (about 14 pounds), and fat mass increased from about 20 percent of the body to 24 percent. Six months after the fast-food diet, the subjects had lost most of the weight gain: 4.7 (+/- 3.1) kg (about 10 pounds).
Still, 12 months after the intervention, body weight was up 1.5 (+/- 2.4) kg (about 3 pounds) compared to baseline (P=0.018). And, the increase was even greater after 2 and a half years with body weight increasing 3.1 (+/- 4.0) kg (about 7 pounds) (P=0.01) on average.
In contrast, researchers found no change in controls compared to baseline after two and half years.