Mom’s cooking is best for the waistline. That’s the message from researchers who blame fat-laden fast food for much of the abnormal weight gain in teenagers.
Adolescents who increased the amount of fried foods they ate outside of the home gained more weight than the amount to be expected for their age group, according to a study in the October issue of Pediatrics.
At the start of the study, those who never or rarely ate fried food away from home, but then a year later increased their intake to four to seven times a week, gained about 0.21 kg/m2 (CI 0.03-0.39).
Children who for the most part bypassed fried foods both at baseline and after a year served as a reference; changes in body mass index were similar for both genders.
The direct association between fried food consumption and changes in body mass index were most pronounced for girls ages nine to 12, said lead author Elsie M. Taveras, M.D., M.P.H., an instructor in ambulatory care and prevention at Harvard Medical School.
While it’s no mystery that fried food is unhealthy, what is not as well-established is whether the current shift away from home-prepared meals toward ready-to-eat foods, many of them fried, is related to any change in body mass index in children, Dr. Taveras said.
Childhood obesity has tripled in the last 20 years, yet “the population has remained genetically stable,” pointing to environmental factors, the authors noted.
The study of more than 14,000 children, ages nine to 14, found that while the weight gain from increased fried food consumption was small, the increase has the potential to snowball into clinically significant weight accumulation.
“Our findings suggest that consumption of fried foods away from home is associated with dietary patterns related to excessive weight gain, atherosclerotic Heart disease, cancer, and Type 2 diabetes,” the researchers wrote. “These findings suggest that early educational efforts to reduce consumption of food prepared away from home may help prevent excessive weight gain and chronic disease risk in youths.”
The study analyzed 7,745 girls and 6,610 boys who were the offspring of participants enrolled in the Nurses’ Health Study II. The children reported their height and weight so that researchers could calculate their body mass index. Beginning in 1996 and yearly until 1999, the children filled out questionnaires asking about their consumption of 132 foods during the previous year.
Every year, the participants were asked, ‘How often do you eat fried food away from home (i.e. French fries, chicken nuggets)?’ The response categories were: never or less than once a week, one to three times a week, four to six times a week, and daily. Because responses to “daily” were sparse, this category was combined with the four-to-six times a week category in the analysis.
Although the study asked participants specifically about fried foods and not how often they frequented fast food establishments, the authors said that past research has shown “fried food away from home is a reasonable proxy for fast food consumption.”
The study found that at baseline in 1996, 3.5% of the girls and 6.0% of the boys reported consuming fried foods away from home four to seven times a week. The older 13- to 14-year-old girls and boys outdid their younger nine- to 12-year-old counterparts (4.4% of older girls and 7.2% of older boys versus 3.1% of younger girls and 5.5% of younger boys).
But by 1999, those figures had doubled for all the teenagers with 7.5% of all the girls and 12.7% of all the boys reporting eating fried foods four to seven times a week.
Changes in body mass index were most pronounced for younger girls and older boys. Young girls, ages nine to 12, who increased their fried food consumption from “never or less than once a week” to “four to seven times per week” a year later gained about 0.52 kg/m2 (CI 0.10-0.93) compared with a gain of 0.03 kg/m2 (CI -0.26 to 0.31) for girls 13 and older.
Conversely, boys ages 13 and older gained more weight (0.46 kg/m2 ; CI 0.10-0.83) when they increased their fried food consumption compared with younger boys ages nine to 12 who lost a little (-0.04 kg/m2, CI -0.44 to 0.35).
“Although the effect may seem small,” the authors wrote, “it is of practical significance because it is the effect of one year of intake of fried foods away from home. Our study suggests that doing this year after year, accumulates to larger weight gains that are clinically significant.”
For children of all ages who managed to reduce their fried food intake over the study period, boys had better luck than girls. Boys who reported eating fried foods four to seven times a week at baseline and then decreased their intake to never or once a week at follow-up showed a decrease in BMI (-0.31 kg/m2).
But girls who cut down their fried food consumption from baseline to follow-up struggled to lose weight and in fact showed an increase in BMI (0.27 Kg/ m2). The researchers said this finding remained even after taking into consideration the possibility that these adolescent girls may have been dieting. Previous studies have shown an association between young girls who diet and weight gain.
The study also found that those who reported consuming fried foods more than four times a week also took in more calories overall. They consumed more processed red meat, whole dairy products, and sugary beverages, ate fewer fruits and vegetables, and were less likely to take multivitamins, the team reported.
Fried foods “may have pernicious effects on body weight and diet quality,” the authors concluded. “Clinicians should consider encouraging adolescents to limit their intake of food prepared away from home and encourage them to eat family dinners together. The benefits of home dining include improved diet quality and also a reduced likelihood of high-risk adolescent behaviors such as tobacco, alcohol, and marijuana use.”
Taveras et al, “Association of Consumption of Fried Food Away From Home With Body Mass Index and Diet Quality in Older Children and Adolescents,” Pediatrics, Oct. 2005; 116; p.518-524.
Revision date: July 6, 2011
Last revised: by Janet A. Staessen, MD, PhD