The quality of life of adolescents who think they are too fat is worse than for adolescents who really are obese.In the course of the KiGGS study, almost 7000 boys and girls aged between 11 and 17 years were weighed and asked about their self-assessment, ranging from "far too thin" to "far too fat." In addition, they all completed a questionnaire about quality of life. As a result of their analysis, the scientists established that about three quarters of adolescents are of normal weight. Almost 55% of the girls, but just under 36% of the boys thought that they were "too fat," although only about 18% of the adolescents were actually overweight. 7% to 8% of the adolescents were underweight.
The quality of life is lower in obese adolescents. However, this correlates to a large extent with self-evaluation. If adolescents think they are "far too fat," they forfeit a lot of their quality of life, whatever their actual weight. This is particularly marked with girls. On the other hand, if they consider their weight "just right," their quality of life is the same as if they were of normal weight, even if this is not true. The proportion of adolescents who think they are overweight has been increasing more rapidly in recent years than the proportion of those who really are overweight.
They found that study subjects on strict diet and exercise programs tend to lose weight more slowly than expected because they eat more on weekends than during the week. The investigators report their findings in the advance online publication of the journal Obesity.Past research had confirmed that people tend to gain weight during the holidays, particularly between Thanksgiving and New Year's, but this is the first study to carefully monitor daily body weight, calorie intake and calorie expenditure for several weeks throughout a year, and to demonstrate that increased caloric intake isn't just a problem during the holidays. It also happens on most weekends.
"We thought weekends would present a problem for some people attempting to lose weight, but the consistency of our finding before and during the interventions was surprising," says first author Susan B. Racette, Ph.D., assistant professor of physical therapy and of medicine. "Subjects in the diet group lost weight during the week, but over the weekend, they stopped losing weight because they were eating more."
Racette's team followed 48 adults between the ages of 50 and 60 who took part in the CALERIE (Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy) study. Body mass index (BMI) ranked subjects as overweight or healthy weight when the study began. None were classified as obese.Following earlier studies demonstrating that mice and rats live longer,healthier lives when on a calorie restricted diet, the CALERIE study is designed to determine whether taking in fewer calories over a long time period will slow down or reverse some of the common markers of aging and disease.
Study participants were divided into three groups: the first lowered their daily calorie intake by 20 percent, a second increased daily physical activity by 20 percent, and a third, control group did not change diet or activity levels. All three groups were monitored for one year. They kept food diaries, tracked exercise with accelerometers and were weighed regularly. Racette says people in the study didn't always realize they were eating significantly more food on weekends.
Before the interventions began, the researchers established "baselines" for each study participant's exercise and eating habits. This pre-intervention data determined that participants consumed the most calories on Saturdays. An average of 36 percent of their total calories came from fat on Saturdays, but less than 35 percent came from fat during the rest of the week. The typical weekend weight gain before the diet and exercise interventions began would have led to an average increase of 9 pounds a year.When study participants were asked either to cut calories by 20 percent or to increase activity by a like amount, the pattern remained the same. Those in the calorie restriction group took in more energy on Saturday. Those in the exercise group ate more on both Saturday and Sunday. As a result, people in the calorie restriction group stopped losing weight on weekends, and those in the exercise group actually gained weight on weekends.
As the researchers move into the second phase of the CALERIE study, looking at more subjects over a longer period of time,they now recommend that participants weigh themselves daily in order to be more aware of their patterns of weight loss and weight gain, particularly on weekends."Planning ahead can't be emphasized enough," Racette says. She recommends packing healthy food if you're running errands,eating a little something so you aren't starving when you arrive at a party, even packing a light lunch before going to the kids' ballgames so that you have a choice other than junk food at a concession stand.