Family Practice Vol. 19, No. 3, 304-309
© Oxford University Press 2002
Selections from Current Literature |
Treatment issues in childhood obesity
Department of Family Medicine, State University of New York at Stony Brook, Stony Brook, NY 11794-8461, USA.
Connolly J, Gargiula L and Reeve D. Treatment issues in childhood obesity. Family Practice 2002; 19: 304–309
Introduction
Obesity is reaching epidemic proportions in the USA and is a growing problem in developed countries. It is associated with a number of co-morbidities, such as coronary artery disease, type 2 diabetes, gall bladder disease and sleep apnoea. The health care cost associated with obesity in US adults is estimated to be 100 billion dollars annually.1
Trends in childhood obesity are paralleling those of adult obesity, with ~25% of American children either overweight or obese.2 Childhood obesity is associated with increased risk factors, such as high cholesterol and hypertension, for chronic illness in adulthood, and with increased presentation of co-morbidities, such as type 2 diabetes, in early adolescence.3,4 These trends in childhood obesity are global, with increasing prevalence in Russia, China and Brazil, as well as the USA. Wang suggests that this trend will lead to a rise in global rates of obesity-related diseases.1
Data from the US National Health and Nutrition Examination Surveys reveal that the prevalence of adult and childhood obesity increased substantially over a single decade. This increase cannot, therefore, be attributed to changes in the genetic makeup of the population. The rapid rate of increase in the prevalence of obesity must be due to the interaction between genetic predispositions and changes in the environment, such as decreased opportunities for physical activity and increased availability of calorically dense foods.5 Such trends speak to the need for family-based behavioural weight management programmes, since families share genetic predispositions, as well as environments.
This article reviews the current literature, specifically examining family-based treatment programmes, types of dietary interventions and macronutrient issues. Epstein laid the groundwork for family-based behavioural treatments with his landmark 1990 publication in which he compares 10-year follow-up data on three family treatment programmes. Golan and colleagues continue work in this area. They examine not only changes in children's weight resulting from family-based behavioural programmes focused on children's weight loss, but also changes in parents' weight and cardiovascular risk factors. Lastly, Spieth and colleagues explore the hotly debated topic of dietary macronutrient content and glycaemic index in the context of behavioural change programmes. This article concludes with recommendations for family physicians in their work with obese children and their families.
Epstein LH, Valoski A, Wing RR, McCurley J. Ten-year follow-up of behavioral, family-based treatment for obese children. J Am Med Assoc 1990; 264: 2519–2523.
Epstein and colleagues hypothesized that treatments designed to reinforce behaviour change and weight loss in obese parents and children will result in greater long-term weight loss than treatments focusing solely on behaviour change and children's weight loss or treatments reinforcing attendance only. Seventy-six obese children aged 6–12 years and their parents were assigned randomly to one of three treatments, child and parent target, child target and non-specific target. Data on 55 children were available at the 10-year follow-up, and there were no significant differences in unavailability for follow-up across groups. All treatment groups met weekly for 8 weeks and approximately once per month for 6 months. Follow-up data were collected at 21, 60 and 120 months. Children in all groups were given 1200–1500 calorie diet prescriptions, and kept diet records. Families were urged to remove all calorically dense foods from the household, and encouraged to exercize aerobically. Contracting, self-monitoring, social reinforcement and modelling, and contingency management behavioural modification techniques were differentially used across groups. In the child and parent target group, families were refunded US$5 for every visit at which the parent and child lost weight, and parents reinforced children's weight loss with home-based incentive systems. In addition, parents and children kept records on caloric intake, exercise and weight, and both parents and children were trained to serve as appropriate role models for family members. Both parents and children were also required to pass quizzes based on material reviewed in class in order to progress along the programme. In the child target group, US$5 refunds were based only on child weight loss, and only children maintained daily records and had to pass quizzes. Both parents and children were trained to role-model desired behaviour. In the non-specific target group, US$5 refunds were granted as a reward for attendance, not weight loss, and children only kept daily records. Participants in group three were given educational material on role modelling, but not trained specifically, and quizzes were not used at all.
The percentage change in weight for height, age and gender was the primary outcome variable. There was a significant group by time interaction, with significant percentage overweight differences at both 5 and 10 years among children in the groups. Children in the child and parent target group showed a significant decrease from baseline in percentage overweight at both 5 and 10 years, while children in the child target and non-specific target groups increased in percentage overweight at both 5 and 10 years. At 10 years, the overweight percentages for the child and parent target group, child target group and non-specific target group were as follows: –7.0%, +4.7% and +13.6%. There were no significant differences in height among the three groups over time. All parents demonstrated a significant decrease in percentage overweight at the end of treatment. However, by 5 years, parents returned to baseline percentage overweight, and by 10 years the mean percentage overweight for the groups ranged from 4.6 ± 10.1% to 10.6 ± 13.4%. Ten-year heights of children were similar across groups, and similar to the heights of parents of the same sex. The authors conclude that if behavioural family-based treatment emphasizing reinforcement for child and parent behaviour change and weight loss is initiated when children are between 6 and 12 years, children's weight loss can persist until young adulthood.
Comment
Epstein's work is quite unique in that it demonstrates long-term effectiveness resulting from a children's weight management programme reinforcing behaviour change and weight loss in parents and children. The study conclusions are well supported by the research design and results.
The reinforcement techniques, i.e. use of money as a reward, and the object of the reinforcement, i.e. weight loss, used in this 1990 study are no longer recommended. More appropriate reward structures should be based on praise and activities that foster parent–child relationships rather than food, money or gifts. The object of the reward should be based on factors directly under the child's control, such as eating and exercise behaviours, rather than on weight loss, which can be affected by genetics or metabolic rate.6
The long-term results for parents are disappointing in that this approach was not associated with parental weight loss beyond 21 months. Further work in this area, exploring long-term treatments and exploration of the development of co-morbidities or risk factors for such is needed. Golan and colleagues begin exploring these issues.
Golan M, Fainaru M, Weizman A. Role of behavior modification in the treatment of childhood obesity with the parents as the exclusive agents of change. Int J Obesity 1998; 22: 1217–1224.
Golan, Weizman and Fainaru examined the differences in children's weight loss and food-related behaviours resulting from group treatment programmes including either parents or children as the agents of change. Sixty obese children were recruited from a middle class public school district in Israel. The participants were 6–11 years old with two parents living at home, and at least 20% over their expected weight for age, height and gender. Children were assigned randomly to a parent-only education and behaviour modification programme (experimental intervention) or a child-only education and behavioural modification programme (conventional intervention). Children's and both parents' height and weight were measured, and parents completed the Social Demographic Questionnaire and the Family Eating and Activity Habits Questionnaire. The habits questionnaire examined four behaviours related to weight loss in children: activity level; exposure to food stimulus; eating related to hunger; and eating style. The outcome variables included weight loss and behavioural changes of parents and children.
In the experimental intervention, parents were split into two subgroups of 15 pairs of parents. Each subgroup attended 14, 1-hour sessions sequenced as follows: four weekly sessions, followed by four biweekly sessions and six sessions held once every 6 weeks. A clinical dietitian conducted each session. All families (including siblings) were required to attend five, 15-minute individual family sessions in order to maintain contact between group sessions. Parents were instructed to alter the family sedentary lifestyle, provide a diet that reduced total and saturated fats and increased mono-unsaturated fats, decrease the family's exposure to food stimuli, apply behavioural modifications and practice relevant parenting skills. In addition, limits of responsibilities were discussed, as well as parental modelling, cognitive restructuring and coping with resistance. Overall, the parent's role was to provide a healthy diet while not restricting the amounts of food eaten.
In the conventional group, 30 children were divided into two groups. Each group attended 30, 1-hour sessions conducted by a clinical dietitian. The sessions were held weekly for the first 8 weeks and biweekly for the remaining 22 weeks. As part of the treatment, each child was given a 6.3 MJ/day diet. Children were taught to follow a sensible diet, restrict caloric intake, increase physical activity, control food stimuli (snacks, sweets, cakes and ice cream), practice problem solving and cognitive restructuring, and use social supports. Individual counselling was provided when a participant missed a session or needed extra help.
Children in both groups showed a significant decrease in the degree of overweight, 14.6% in the experimental group (P < 0.001) versus 8.4% in the conventional group (P < 0.01). However, the weight loss in the experimental group was significantly greater than the weight loss in children in the conventional group. The activity level in both groups was ~3 hours per week. Both interventions failed to increase the mean weekly duration of physical activity significantly, although there was a trend towards increased activity in the experimental group. Television viewing time did not change in either group for parents or children after the intervention. Exposure to food stimuli was similar in each group prior to the intervention. At the end of the study, there was a significant reduction in all four stimuli foods available in the homes of children in the experimental group: snacks (P < 0.001), sweets (P < 0.001), cakes (P < 0.01) and ice cream (P < 0.0001). In the homes of the children in the conventional group, there was only a significant reduction in the availability of ice cream (P < 0.01). In addition, children's behaviour regarding these stimuli was also measured. After the intervention, it was noted in the experimental group that there was a significant increase in children asking permission to buy or take snacks and sweets. It was found that 89.7% of parents in the experimental group, compared with 55.2% in the conventional group, asked the child if he/she was hungry when the child asked for food (P < 0.01). When the child stated he/she was not hungry, 33% of the parents in the experimental group versus 61% of the parents in the conventional group told their child to eat anyway. Parents were asked how often their children eat in front of the TV or an open refrigerator, from the pot, while doing homework or reading, between meals and while stressed, angry, bored or frustrated. There were significant changes in behaviour in the experimental group in all eating styles, while there was only a significant decrease in eating between meals in the conventional group. Mean energy intake at baseline was similar in both groups, and both groups significantly decreased caloric intake. However, it was found that children in the experimental group decreased energy intake by 26.5% versus 17% in the conventional group (P < 0.001). These decreases in calorie intake correlated with the decreased exposure to food stimuli at home (r = 0.43; P < 0.01) and with reduced poor eating styles (r = 0.32; P < 0.05). In addition, the behavioural changes explained 27% of the variance in overweight reduction. The authors conclude that the experimental treatment induces greater weight loss than the defined conventional treatment.
Comment
Golan and colleagues explored the role parents play in facilitating children's weight loss, and they attribute the significant differences in weight loss to the agent of change. Due to the need to collect data, the agent may not be so simple to define, since parents in the child as agent group were weighed and completed surveys likely to increase awareness of family eating habits. On the other hand, children of parents in the parent as agent group attended five short intervention sessions, were weighed and kept food records. Therefore, within any participating family, there were probably multiple agents of change. A third group with parents and child attending treatment sessions and acting as agents of change would have been an interesting addition to this study, and may have led to even more dramatic results.
Although the concept of agent of change is an important factor, a secondary factor may have contributed to the difference in weight loss between the two groups. The conventional group was given a controlled calorie diet prescription whereas the experimental group was educated on a family-based environmental and behavioural change programme. A more direct method of testing for differences associated with agent of change would have been to give the child agent group a similar environmental- and behavioural-based programme. A structured dietary approach may lead to feelings of deprivation and a sense of failure if the diet prescription is not followed consistently. Such feelings of failure can lead to decreased self-esteem and hinder weight loss. Therefore, the different dietary approaches between the groups add an uncontrolled confounding variable.
Although the experimental group demonstrated greater weight loss at the termination of the intervention, the lack of direct behavioural treatment with the children leaves them with poor skills to make appropriate food choices as they get older and eat more often in the company of peers rather than parents. Therefore, maintenance of weight loss over time may be compromised. Unfortunately, results were not tracked after termination of the programme.
Golan M, Weizman A, Fainaru M. Impact of treatment for childhood obesity on parental risk factors for cardiovascular disease. Prevent Med 1999; 29: 519–526.
Golan, Weizman and Fainaru focus on the effects on parental weight, eating and activity behaviours, and cardiovascular risk factors when participating in a family-based approach for treatment of their children's obesity. The authors used the same subjects and research protocol as described in the previous study. Along with height and weight, blood pressure, serum insulin, serum glucose, total cholesterol, HDL, LDL and triglycerides were measured before and after the intervention period. As mentioned earlier, parents of both the experimental and conventional groups filled out the Social Demographic and Family Eating and Activity Habits Questionnaires at baseline and at 12 months.
Attendance in both groups was 70%. In the parent-only group, both parents attended the meetings 47% of the time, mothers alone attended 16% of the sessions and fathers alone attended 6% of the sessions. When parents missed a group meeting, a letter was sent home to summarize what was covered in the session. Child weight loss was found to correlate highly with the mothers' (r = 0.72, P < 0.001) and fathers' (r = 0.55, P < 0.01) attendance. Mothers' and fathers' weights at baseline correlated negatively and significantly with their attendance at sessions; therefore, the heavier the parent the more likely they were to miss sessions (r = –0.55, P < 0.01, r = –0.36, P < 0.05). However, fathers' risk for cardiovascular disease decreased with greater attendance (r = –0.54, P < 0.01).
Mothers did not show a decrease in overweight in either group. Seven of the 21 obese fathers in the experimental group lost >10% of their baseline weight. The differences in the paternal weight reduction when compared between groups was significant (experimental group 30.1 ± 2.5–25.7 ± 2.4; conventional group 23.9 ± 5.4–24.1 ± 3.9; P < 0.05). At the end of the intervention, fathers involved in the experimental group were found to have a 16% reduction in glucose levels (P < 0.05) and a 21% reduction in triglyceride levels (P < 0.05). Minimal changes were found in the conventional group among fathers. The difference between groups in mean fasting glucose among fathers was statistically significant (P < 0.05). Mothers in the experimental group showed an 8% reduction in LDL (P < 0.05) and a trend towards decreased total cholesterol. These decreases in lipids in the mothers in the experimental group were significantly different from the changes in lipids in the mothers in the conventional group whose lipids trended up (P < 0.02).
When assessing poor eating styles, it was found that both parents in the experimental group improved significantly from baseline measures compared with parents in the conventional group (P < 0.05). Fathers in the conventional group increased their physical activity level by 30% compared with 2% in the conventional group; this was not found to be a significant difference. However, mothers in the experimental group increased their level of physical activity by 60% (P < 0.01) compared with an increase of 10% in the conventional group. There was also a significant difference in the reduction of food stimuli found in the home between groups (P < 0.05). This reduction correlated with the change in overall parent eating style (r = 0.34, P < 0.01).
Overall, the authors found that a family-based approach to treating childhood obesity can have a positive effect on the child, as well as on parents through weight loss, improved eating and activity behaviour and improved risk factors for cardiovascular disease. The improvements found are significantly smaller in parents who are not directly associated with their child's obesity treatment.
Comment
Significant improvements in cardiovascular risk factors were limited to the parent as the agent of change group. However, the factors positively affected within this group were limited to LDL cholesterol in mothers, and weight, glucose and triglycerides in fathers immediately after the intervention. The long-term impact of this type of treatment is not known. Clearly, however, the results are limited secondarily to the lack of long-term follow-up data. As mentioned previously, a third group including both parents and children trained in behaviour modification and the provision of social support and modelling would have been an interesting addition to the study. Work needs to be done to explore ways of enhancing and extending the effectiveness of this approach.
Self-reported positive changes in eating behaviours, presence of household food stimuli and physical activity did not correlate with changes in weight in parents. Such results, however, did correlate with changes in children's weights. Parents' truthfulness in answering the survey questions relating to changes in their own behaviours are therefore, suspect. The finding that parents more severely overweight at baseline had poorer attendance records indicates a need for early family intervention of more intensive treatment for these parents.
Spieth LE, Harnish JD, Lenders CM et al. A low-glycemic index diet in the treatment of pediatric obesity. Arch Pediatr Adolesc Med 2000; 154: 947–951.
Spieth and colleagues compared the efficacy of a low glycaemic index diet with that of a low fat diet, a more conventional approach, in treating childhood obesity. Glycaemic index is defined as the relative rise in blood glucose and insulin occurring after consumption of a food containing a standard amount of carbohydrate. Although controversial, glycaemic index is generally reduced by high fibre, fat or protein content. In this study, 64 participants completed the low glycaemic index (L-GI) protocol and 43 participants completed the reduced fat protocol. Children were recruited from a pre-existing hospital-based weight management programme. At the start of the study, the average ages were 10.6 ± 4 and 10.2 ± 3.1 and the average body mass index (BMI) was 32.5 ± 7.3 and 34.5 ± 7.2, respectively. The main outcome variable was BMI. Each patient received a thorough physical examination, dietary counselling and lifestyle counselling, emphasizing a reduction in physical inactivity and an increase in physical activity. Ideally, treatment sessions were held once a month for 4 months and then as needed. These sessions were conducted by a dietitian and included at least one parent. Goals were developed to meet the individual needs of the child. In addition to diet and exercise counselling, problem-focused behaviour therapy was provided by a psychologist for participants when recommended by a team member.
The reduced fat protocol included diet prescriptions resulting in a 250–500 calorie deficit per day. Emphasis was placed on decreasing the consumption of high-fat, high-sugar, energy-dense foods, and increasing consumption of grains, vegetables and fruits. The percentages of macronutrients recommended were as follows, 15–20% protein, 55–60% carbohydrate and 25–30% fat. In the L-GI group, emphasis was placed on food selection rather than energy restriction; therefore, participants were encouraged to eat until satisfied and snack when hungry. Patients were instructed to combine L-GI foods with proteins and fats at every meal and snack. Education material was provided which divided foods based on glycaemic index into the following groups: vegetables, legumes and fruits (low glycaemic index foods), lean proteins and dairy products (protein foods with low glycaemic index), whole grain products (moderate glycaemic index foods) and refined grain products, potatoes and concentrated sugar (high glycaemic index foods). The macronutrient goals for this cohort were 45–50% carbohydrate, 20–25% protein and 30–35% fat.
The overall mean change in BMI in the L-GI group was –1.53 kg/m2 versus –0.06 kg/m2 in the reduced fat group (P < 0.001) prior to adjustment for age, sex, ethnicity, duration of follow-up, behavioural therapy and baseline BMI. After adjustment, change in BMI remained statistically significant [–1.15 kg/m2 versus 0.3 kg/m2 (P < 0.01)]. Change in unadjusted body weight was –2.03 kg for the L-GI group and 1.31 kg for the reduced fat group (P < 0.001). After adjustment, the –1.16 kg (L-GI) versus 1.44 kg (reduced fat) was found to be statistically significant (P < 0.01). Analyses were also conducted for participants placed in one of three BMI tertiles (<28.3, 28.3–34.9 and >34.9) within each cohort. In each BMI tertile, it was found that patients in the L-GI group had a significantly larger decrease in BMI than those in the reduced fat group.
Similar significant results were found when subgroups of patients in each cohort not receiving behavioural therapy were compared. The authors conclude that a low glycaemic index diet may be an effective nutrition alternative for the treatment of childhood obesity.
Comment
Spieth and colleagues provide an interesting exploration of alternative nutrition approaches for obese children. However, the authors may be prematurely attributing the success in the experimental treatment group to a low glycaemic index diet as there are methodological factors that limit such conclusions. First, subjects were assigned to intervention groups based on schedule availability. This non-formal random assignment may be the source of systematic bias. Secondly, children in the L-GI group were not given a structured diet, but instead recommendations regarding types of foods and tools to focus on internal signals of hunger and fullness. The authors claim that children in this group were following a low glycaemic index diet with ~45–50% of total calories derived from carbohydrate; however, it is unclear how children would have been able to construct daily diets meeting these recommendations without meal pattern type diets. In addition, food records were not kept to verify children's actual intake. It is feasible that the children in this group met with greater success due to the non-diet approach and focus on hunger and satiety or differences in macronutrient distribution. Lastly, changes in sedentary behaviours or increased physical activity are additional confounding variables that are poorly controlled.
The use of glycaemic index in menu planning is an interesting theoretical construct; however, it is difficult to operationalize in practice. Glycaemic indices for types of food vary significantly based on growing conditions, method of preparation, food quality or length of cooking. For example, increased ripeness of a banana can double its glycaemic index.7 Spieth and colleagues developed nutrition education material that attempts to distinguish foods based on their glycaemic index, but their food groups may be too simplistic to control for glycaemic index. In addition, how a food is combined with other foods in a meal alters its glycaemic response, as a meal has a glycaemic index of its own based on all food components of the meal. Glycaemic index of a meal is also influenced by the total carbohydrate content of the meal. Since the authors did not collect food records to attempt analysis of glycaemic index of selected meals and snacks, it is inappropriate to assume that the children were indeed following a low glycaemic index diet. For that matter, children in the low fat diet group may have adopted a low glycaemic index diet as they were instructed to avoid sweets, and to increase their vegetable and whole grain consumption. The demonstrated success of the treatment group may have been a result of a lower total carbohydrate intake. Therefore it is difficult to determine the key factors contributing to the success of the experimental group.
Conclusions
The literature reviewed supports the short- and long-term efficacy of family-based behavioural programmes for the treatment of childhood obesity. Long-term parental weight loss, however, is more refractory, further supporting the importance of aggressively treating childhood obesity before it becomes an adult problem.
The US expert committee of the Maternal and Child Health Bureau and the Department of Health and Human Services has published recommendations for the evaluation and treatment of childhood obesity.8 Evaluation should be based on BMI and the new National Center for Health Statistics growth curves based on BMI. Children or adolescents with a BMI greater than the 85th percentile for age and gender should be evaluated carefully with an emphasis on assessment for complications associated with obesity. A recent large change in BMI should also prompt an evaluation.
The assessment should include an evaluation to identify underlying syndromes, such as genetic, endocrine or psychological disorders, and secondary complications. A thorough assessment should also include evaluation of the child's and family's readiness to change eating and exercise habits, as well as the physical environment to support such behaviour changes. Depending on the severity of the child's obesity, individual and/or family therapy may be necessary to advance readiness to change. The issue of family readiness to change was not addressed by Golan and Epstein, and may have been an important confounding variable. A global dietary assessment to evaluate eating habits and patterns, including daily and weekly intake of high calorie foods and beverages, fast foods and other meals and snacks eaten outside the home, is essential. Lastly, a physical activity history is necessary to identify opportunities to increase energy expenditure. This history should include sedentary behaviours, such as computer use and television viewing, as well as structured physical activity and free play. Epidemiological research suggests that simply decreasing sedentary behaviours by limiting television viewing can facilitate weight management efforts.9,10
The general goal of treatment is the establishment of healthy eating and physical activity patterns. For children between 2 and 7 years of age, weight maintenance, which will allow for a decrease in BMI as the child grows, is recommended. For children in this age group with a BMI greater than or equal to the 95th percentile and with secondary complications, weight loss is recommended. For children over the age of 7, weight maintenance is recommended. However, if BMI is greater than the 85th percentile and there are secondary complications, weight loss is recommended. Weight loss is also recommended for children older than 7 with a BMI equal to or greater than the 95th percentile, even in the absence of secondary complications. The recommended rate of weight loss for children is ~1 pound per month. The general weight goal for obese children is a BMI below the 85th percentile.
Treatment recommendations of this committee are consistent with the work of Epstein and Golan. The committee's recommendations provide detailed characteristics of effective treatment programmes, including strategies for modifying the home environment, improving eating habits and increasing energy expenditure. Physicians may choose to provide office-based treatment, refer to a specialized clinical dietitian or refer to a paediatric weight management programme run by health care professionals. For those physicians interested in initiating office-based treatment, frequent visits with the child and/or parents are recommended to establish a structured goal-oriented programme. Based on the authors' clinical experience, the most effective interventions to establish over time are as follows: limit television viewing and computer use to a maximum of 2 hours per day, eliminate high calorie beverages (fruit drinks, soda, iced tea and lemonade), limit fruit juice to 12 ounces per day, offer only low fat milk for children over 2 years, establish eating style rules (eating only in the kitchen, no other simultaneous activities including television viewing), encourage the consumption of breakfast and accumulate 30 minutes of physical activity most days of the week. In addition, appropriate parenting skills are critical for the child's success and should be discussed. Examples of appropriate parenting are as follows: praise the child's behaviour often, never use food as a reward, prompt a child to eat when hungry and stop when full, provide a variety of healthy food options and allow the child to select which foods and how much to eat, remove temptations and role-model healthy eating and physical activity habits.
The committee did not address the issues of macronutrient distribution or glycaemic index. However, this topic represents an active area of research as discussed by Spieth. In the authors' clinical experience, both adult and children benefit from the combination of high fibre carbohydrates with either lean proteins or healthy fats, such as whole wheat crackers and hummus, or apple with natural peanut butter. Such combinations increase satiety and may reduce the insulin response, which is an important consideration in this population with a high risk for insulin resistance.
In closing, family physicians can play a significant role in slowing the childhood obesity epidemic. The research indicates that early detection and a structured family-based behavioural approach to weight management can lead to long-term weight loss in children.
References
1
Wang Y. Cross-national comparison of childhood obesity: the epidemic and the relationship between obesity and socioeconomic status. Int J Epidemiol 2001; 30: 1129–1136.
2
Troiano R, Flegal K. Overweight children and adolescents: description, epidemiology, and demographics. Pediatrics 1998; 101: 497–504.
3
Dietz WH. Health consequences of obesity in youth: childhood predictors of adult disease. Pediatrics 1998; 101: 518–525.
4
Hill JO, Trowbridge FL. Childhood obesity: future directions and research priorities. Pediatrics 1998; 101: 570–574.
5
Rosenbaum M, Leibel R. The physiology of body weight regulation: relevance to the etiology of obesity in children. Pediatrics 1998; 101: 525–539.
6 Epstein L. Family-based behavioural intervention for obese children. Int J Obesity 1996; 20 (Suppl 1): S14–S21.[Web of Science]
7 Wolver TMS. The glycemic index: flogging a dead horse? Diabetes Care 1997; 20: 452–456.[Abstract]
8 Barlow S, Dietz W. Obesity evaluation and treatment: Expert Committee recommendations. The Maternal and Child Health Bureau, Health Resources and Services Administration and the Department of Health and Human Services. Pediatrics 1998; 102: E29.
9
Crespo CJ, Smit E, Troiano RP, Bartlett SJ, Macera CA, Anderson RE. Television watching, energy intake and obesity in US children. Arch Pediatr Adolesc Med 2001; 155: 360–365.
10
Jeffery R, French S. Epidemic obesity in the United States: are fast foods and television viewing contributing? Am J Public Health 1998; 88: 277–280.
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||