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How does the high fat american diet contribute to obesity Document Transcript

  • 1. Obesity: How does the High Fat American Diet Contribute to Obesity? A Research Paper Submitted by Name of Student Name of Establishment Class XXXX, Section XXXX, Fall 2012
  • 2. 2 Contents Abstract......................................................................................................................................3 Introduction................................................................................................................................4 Main Findings of the Articles.....................................................................................................5 Results......................................................................................................................................16 Discussion................................................................................................................................19 Conclusions..............................................................................................................................21
  • 3. 3 Abstract Background. Obesity is a chronic disease causing pathological changes and complications in one’s body. It has already displaced infectious diseases and undernutrition as the main killers of people.1 In the modern world it has become so widespread that sometimes it is called an epidemic. More and more people suffer from it and its detrimental consequences. The increasing prevalence of obesity has a considerable effect on health care spendings.1 That is why this is the subject which requires additional researches. Though there already exist health care services aimed at preventing and treating obesity, still an effective medical framework should be developed in order to successfully combat the disease.1 Objective. The purpose of the research is to analyze available scientific literature discussing the problem of obesity within American community and, in particular, the contribution of high-fat food to obesity. Methodology. The Pubmed database as well as Google Academy search engine were used. In order to find relevant articles the following keywords were entered: obesity, high-fat food, American diet, fast food. After the search, fifteen articles were chosen for analysis on the basis of which the given review was produced. Results. The findings of the research on the basis of articles were attentively analyzed and summarized in the Overview Table. The details of each study can be found in the section entitled Main Findings of the Articles. Conclusion. Obesity prevalence among American community is a multifactorial problem. Each of the analyzed articles addresses it from different sides to produce a complete picture. One of the main reasons of it spreading among all groups of population is consuming unhealthy food, such as fast food, rich in fat.
  • 4. 4 Obesity: How does the High Fat American Diet Contribute to Obesity? Introduction The issue of healthy food and healthy life-style is, without doubt, a sensitive and ever- lasting one. That is why it so much occupies researchers’ minds all over the world. Obesity, being highly discussed throughout the entire history of the mankind, still remains a topical question. Furthermore, it is often said to have reached critical proportions. Nearly 250 million people in the world are considered to be obese and it has been predicted that the number will reach 300 million in 10-15 years.1 Obesity is a chronic disease caused by consuming more calories than are used by an individual. And like any other dangerous disease it causes pathologic changes in one’s body: it produces such clinical complications as diabetes mellitus, gallbladder disease, coronary heart disease, osteoarthritis and even some forms of cancer, etc. by releasing cytokines and other products of fat cell metabolism.1 The results of such consequences are obvious: people become weaker and costs for health care start to soar. A good way out would be effective preventive measures. But in order to avoid something beforehand, it is of utmost importance to define its reasons and triggers. Since obesity is considered a multifactorial disease, it provides a medical framework in which one should regard both preventive measures and treatment techniques.1 In the given paper we will try to analyze and critically assess various articles discussing the problem of obesity within American community and provide an individual review. To be specific, the point of our focus will be high-calorie and high-fat food, so popular among different social groups of the USA, and its contribution to obesity.
  • 5. 5 Main Findings of the Articles Pretlow 2011 aims at studying possible addiction to pleasurable foods among the teens and preteens aged 8-21. For this reason, an open-access website for those suffering from obesity was established: it was previously thought that it would help the young people to lead healthy life-style and, finally, find the core factors that undermine their efforts in successful weight losing. The research and data analysis lasted for nearly ten years. Online bulletin board posts, transcripts of chat rooms and poll responses were collected and thoroughly examined. A special focus was on words teens and preteens use to describe their weight problems, appearance and possible addiction to food. The analysis of all records2 demonstrated that online anonymity caused striking honesty, since young adolescents do not feel comfortable discussing their problems face to face. The majority of collected data from 94% of females, 5% of males and 1% of sex unknown contained hints of deep misery concerning participants’ appearance, continuous teasing, physical limitations, choice of clothes, dating issues, etc. From the young people’s words it became obvious that overeating pleasurable foods, despite full realization of its consequences, was absolutely common among them. The main reasons turned out to be comfort eating, stress eating, boredom eating and mindless or unconscious eating. By using DSM-IV Substance Dependence criteria the author has come to conclusion that comfort eating and dependence on pleasurable food may be one of the reasons of childhood obesity, though no conclusions are possible as to the prevalence of comfort eating or addiction to food. This poses a new problem that should be addressed in the nearest future. New researches should be conducted in order to find out for sure whether such a phenomenon as food addiction exists and how it should be solved with regard to children obesity. Sampey et al 2011 puts forward a new model of reflecting human obesity trends in modern society. The authors described in detail an experiment with male Wistar rats having
  • 6. 6 arrived at definite conclusion that its results directly reflected metabolic processes in humans. The experiment was conducted in the following way: rats were divided into four experimental groups. The first group had typical food (common chow). The second one was on low-fat diet, the third one – on high-fat lard diet, while the last one consumed what is typically known as high-fat, high-salt, low-fiber, energy dense cafeteria (CAF) food, i.e. regular human snacks such as chips, cookies, processed meats, etc. During the experiment period rats were closely monitored on calories intake and weight gain. At the end of the experiment all groups of rats underwent a number of tests such as glucose tolerance, insulin sensitivity, tissue analysis and metabolic changes. During all the tests3 it was found out that those rats on CAF diet gained weight the most. Besides, considerable metabolic alterations were spotted: rats experienced insulin resistance, elevations in white and brown adipose mass and its inflammation as well as pancreatic islet dysfunction. Those on high-fat diet demonstrated similar or intermediate weight gain. Judging from the results the authors have concluded that CAF diet model better than lard-base high-fat diet reflects possible metabolic changes in human organism and is more responsible for rapid onset of weight gain observed in today’s modern society. This conclusion may be an important implication as far as American unhealthy diet is concerned: people should choose what they eat more thoroughly, paying special attention not to what is easily accessible, but to what will not lead to detrimental consequences. However, all the experimental components limit the CAF data interpretation in the way that it is difficult to conclude as to the role or mechanism of a specific food constituent (for example, high-fat or high-sucrose) in weight gain associated with CAF diet. Boggs et al 2011 conducts a research regarding weight gain in African-American women in connection with the food they consume. The research lasted for 14 years and every two years women reported on their dietary pattern (times of certain food consumption per
  • 7. 7 day), current weight and height by filling in special questionnaires. On the basis of the given data BMI (body mass index) was calculated (weight in kilograms divided by squared height in meters). The role of such important factors as education, age, geographic region, alcohol intake, smoking status, menopausal status, vigorous activity (which was to be further specified), etc. were also assessed and taken into consideration. In order to verify data concerning physical activities, some of the participants wore activity monitors. In the process of research4 two dietary patterns were distinguished: vegetables/fruit diet including vegetables, fruit, whole grain, fish, legumes, etc. and meat/fried foods diet consisting of French fries, chicken, processed meat, etc. As a rule, women on a vegetables/fruits diet were older, more educated, less likely to smoke and physically active and gained less weight. On the other hand, representatives of meat diet were younger, less educated, more inclined to drinking and smoking and gained more weight. After analyzing the results, the authors have come to conclusion that healthy dietary pattern plays a major role in reducing body weight in African American women and helps them maintain a proper life- style. This is one more well-based piece of evidence of how important appropriate diet pattern is. However, one should not forget about the limitations of the study: the use of food frequency questionnaires to estimate dietary pattern and self-reported measures of body size, which may not be 100% true altogether. Giesen et al 2011 takes up researching of how providing calorie information or price increase on high-calorie food influences the choice of the lunch. For this experiment 178 participants (95 men and 83 women) were chosen from a university in the northeast United States. Their task was to choose food for lunch three different times. Each time price for the lunch consisting of high-calorie products was increased by 25%. Besides, three other factors were taken into account: budget of the student (low vs. high), calorie information (provided or not provided) and dietary restraint (high vs. low restrained eaters). Participants were
  • 8. 8 randomly assigned to four different conditions: high budget and provided information on calories, high budget, but no calorie information, low budget and provided calorie information and, finally, low budget with no calorie information. Such characteristics of participants as BMI, age, level of hunger, restraint scale were also measured. The results of the study demonstrated5 that demand for high-calorie food decreased with the increase of restraint score. Secondly, hunger proved to be an important covariate, which resulted in increasing of demand for calories with the increasing of hunger. Thirdly, the analysis showed an essential effect of tax and calorie information. These two factors proved to interact with each other: if no calorie information was provided, then price increase on high-calorie products led to fewer calorie purchases and, vice versa, if calorie information was provided, then price increase did not result in fewer calorie purchases. Judging from the results of the study, the authors have concluded that tax increase of ≥25% will make almost everybody buy fewer calories. Achievements of the study may be used in developing public policies in order to decrease prevalence of obesity. As for the limitations, the tax effect could be slightly different under real-life conditions, since students saw the same menu all the time, because three price conditions were not randomized. Andreyeva et al 2011 tries to establish connection between TV exposure to advertising of fast food and soft drinks and the level of these products consumption among children aged 6-11. For this reason, the authors used different types of surveys, including questionnaires for children themselves as well as for teachers and school administrators, interviews with parents by phone, etc. On the basis of these data a number of children were chosen as eligible for research. However, later a number dropped due to participants not having provided certain information such as weight and height, socio-demographic characteristics, time of TV viewing, soft drinks and fast food consumption, etc. Finally, those chosen for participation
  • 9. 9 were assessed on regularity of soft drinks and fast food consumption and duration of TV watching. The results of the study6 turned out to be the following: exposure to 100 incremental TV advertisements of soft drinks during the period of 2002-2004 was associated with 9.4% increase in consumption of these products in 2004. Similarly, with the same exposure to fast food ads, 1.1% increase in children’s consumption of these products was associated. The authors have concluded that the increase of children’s exposure to advertising of fast food and soft drinks results in increased consumption of these products. These achievements may be used when planning advertising policy for some companies or for officials to take into account when preventing obesity among children. However, the study had a number of limitations: survey measures were based on children’s self-reports; there was lack of advertising data from children living outside top 55 designated marketing areas and no direct link between advertising and children’s body weight could be established. Anderson et al 2011 investigates relation between frequency of eating at fast food restaurants and obesity prevalence among Michigan adults. For this purpose, the authors analyzed the results of random-digit telephone survey, which consisted of 12 questions concerning food consumption and compared them with the data on obesity prevalence in Michigan. For the research, the participants aged 18-64 were chosen. Elderly people were not considered eligible due to poor health condition. The study also used typical for Behavioral Risk Factor Surveillance System questions to define categorical variables such as race, sex, age, household income, education, etc. The results of the research7 were the following: only 12% of Michigan adults never visited fast food restaurants; 9% went there less than once per month. Generally speaking, 80% of Michigan adults visited restaurants with fast food at least once per month and 28% went there regularly, i.e. twice or more times per week. Such regular fast food consumption
  • 10. 10 turned out to be especially typical among younger men, though not significantly associated with education, race or household income. The authors have concluded that prevalence of obesity increases with frequency of going to fast food restaurants, from 24% for those going less than once a week to almost 33% for those going there more than three times a week. The research directly reflects the obesity problem so typical among U.S. population; however, it has its limitations: excluding those people that do not use household telephones and nonresponse of a number of potential participants to the telephone call. Boyland et al 2011 wants to determine whether the level of TV ads watching among children influences their food preferences. The research was conducted in the northwest England with the children aged 6-13. The procedure was the following: children were showed either food or toy ad on two separate occasions with two-week interval in order to avoid likelihood of children remembering their previous response. Then they had to complete TV watching questionnaire, commercial recognition task and food preference measure. The latter one included different types of food, such as high-fat, high-carbohydrate, high-protein and low-energy, each of the group having eight items to choose from. After the research8 , the authors have come to conclusion that the high level of exposure to TV ads increases preferences for both branded and nonbranded food items. Children with high level of previous exposure to TV advertising are more responsive to food promotion that those with lower previous exposure. The study has proved a considerable role TV advertising plays in children’s choice of food. As a result, TV ads may have detrimental effects on their risk of consuming unhealthy food and becoming obese, since high level of TV watching is usually associated with poor dietary habits. Guendelman et al 2011 conducts two slightly different experiments in order to check a hypothesis that American immigrants experience pressure as far as their American identity is concerned and that this fact forces them to choose more unhealthy and calorie-high
  • 11. 11 traditional American food. The essence of the first experiment was as follows: some of Asian Americans were put to test by asking of their knowledge of English and some were not. After that they were asked to list their favorite food. The second experiment consisted in creating fake food delivery website with Asian and American cuisine options. Some of the participants, having been invited to choose food they wanted, were asked if they were really Americans and some were not, before giving them an opportunity to look at food on web-site. These interesting manipulations with identity threat9 (asking about knowledge of English and their nationality) proved that, feeling their ethnicity was put to question, Asian Americans in both experiments tried to “look” more American by choosing what is typically considered as American unhealthy high-calorie food. On the other hand, the group of Asian Americans that were not asked questions about knowledge of English or their real identity, did not feel any identity threat and, as a result, were more willing to choose Asian food. Finally, White Americans, whether having been asked about the English language or not, did not display any behavioral differences under both conditions. The authors of the research have concluded that serious challenges to American identity can result in increased consumption of American food, though it contains more calories. It goes without saying that such a phenomenon is not absolutely positive: Asian Americans or any other ethnic minority should not raise suspicion to their identity when not eating unhealthy food. Fulkerson et al 2010 presents us with a pilot study concerning obesity prevention program among children called Home Offerings via the Mealtime Environment (HOME), which is aimed at introducing healthy food at family meals. The main objective was to test program’s feasibility in order to extend its framework. 44 child/parents dyads were chosen in intervention and control condition (22 in each group). The program included five 90-minute sessions during which the families were exposed to hand-on meal preparation, discussion group for parents, building of cooking skills, nutrition education, etc. All the participants
  • 12. 12 were assessed at baseline, after intervention and then six months later, which included data on their anthropometry, dietary recalls, food availability at home, meal offering inventory, psychosocial surveys. Data analysis10 demonstrated that 95% of parents and 71% of children were absolutely satisfied with sessions. And in comparison to control children, intervention children were more successful as far as development of preparation skills is concerned. Besides, they demonstrated a tendency to consume more vegetables and fruits and were characterized by higher intake of key nutrients and that means good health condition in the future. Though obesity did not differ with regard to type of condition, the authors of the study have concluded that HOME program is fully feasible and may be used as an effective obesity prevention program in the future, despite its limitations: it was applied mostly in Caucasian and highly educated families, which were already used to frequent eating together, and overlooked representatives of other cultural groups, less educated families and those who rarely had family meals. Lanza et al 2012 aims at proving that so-called “built environments” are an important factor in increasing or, otherwise, decreasing health. Built environment represents a mixture of societal factors such as crime rate, health related issues, average income, cost of living, level of physical activity, nutrition environment, race distribution, etc. within a specific area and, generally speaking, forms each community’s eating, working and living space. In their study, the authors tried to compare built environments inside two-mile-radius circle of two elementary schools. For this purpose, they collected information on the above-mentioned constituents of any built environment and conducted a short survey among the students of both schools in order to find out more about their lifestyle and eating behavior. The results have demonstrated11 that different socioeconomic environments will have different influence on health within a specific community: though physical environments may
  • 13. 13 seem similar, the differences in priorities and resources in communities promote dissimilar ways of thinking. For example, communities with low income, but large number of minorities have the highest risk in attaining chronic diseases, since they are more likely to live in the areas with limited access to healthy food and facilities for physical activity. Children’s knowledge on healthy food and lifestyle, basically, depends on what they see around in the environment they live in. For example, one of the schools had their committee aimed at setting good example for their children in eating behavior and the other did not. As a result, it would have an immense influence on children’s way of thinking. Thus, the authors have concluded that significant positive changes should be introduced in built environment of different communities in order to support healthy lifestyle and avoid obesity. Smith et al 2010 tries to investigate how tax increase on caloric sweetened beverages may influence obesity rate and consumption of added sugars. The authors used datasets of actual consumer purchases from Nielsen Homescan panels and individual daily beverage intake from National Health and Nutrition Examination Surveys (NHANES). Using the purchase and demand system data the authors attempted to estimate how beverage- purchasing decisions would change when price for sweetened beverages increased. The study12 calculated that a tax-induced 20% price increase on caloric sweetened beverages could foster an average reduction of 37 calories consumed per day by adults and an average of 43 calories per day consumed by children. This would result in 3.8-pound reduction of body weight over a year in adults and 4.5-pound reduction in children. Furthermore, these reductions in calorie consumption would foster decline in overweight and obesity prevalence within all categories of population. Faced with such a tax, supposedly, consumers would reduce their consumption level of sweetened beverages trying to substitute them by nontaxed and healthier products such as milk, juice or simply water. However, actual
  • 14. 14 impact of the tax will depend on many factors, for example, whether beverages are consumed away from home or not and on market strategies of beverage manufacturers and retailers. Currie et al 2010 analyzes the influence of fast food restaurants proximity on obesity rates within especially vulnerable population groups of school children and pregnant women. The study examines data from three main sources: California public schools, Vital Statistics Natality from Michigan, New Jersey and Texas and National Establishment Time Series Database, storing information on restaurants. All of these sources provided the authors with the detailed valuable data on level of fitness among schoolchildren, mothers and their children’s birth conditions, names and addresses of all available places to eat. After thorough data analysis13 the authors of the research have obtained the following results: for children, a fast food restaurant situated within 0.1 mile from school is associated with at least 5.2% increase in obesity rate. On the other hand, for pregnant women, a fast food restaurant situated within 0.5 mile from her residence results in a 1.6% increase in the probability of gaining 20 kilos. However, the given effect is larger for African-American and less educated women. The study has concluded that there is a significant effect of fast food restaurant proximity on the risk of obesity, though its magnitude is different for adults and children. Raynor et al 2011 studies the relationship between child and parent liking and parent and child intake of certain products. For this purpose, 135 parent/child dyads were chosen which were willing to share information on their dietary intake and food preferences during attending a certain number of meetings. In addition to this, such basic data as child’s BMI, race, gender, age and parents’ education and marital status were recorded. After the cross-sectional analysis14 the researchers obtained the following results: parent’s intake was positively related to children’s intake of all food groups with the exception of sweetened beverages and child’s liking was only significantly related to the
  • 15. 15 intake of vegetables. Generally speaking, in young overweight or obese children parent’s intake was more related to child’s intake of specific food groups than child’s and parent’s liking of these specific food groups. The authors’ conclusion was that changes in parent’s intake could be an important factor in helping overweight or obese children to also change their dietary intake, as far as healthy food is concerned. However, the study was characterized by some limitations, which included the choice of fairly homogeneous sample, i.e., basically, white families with overweight or obese children and it is still unknown whether the same results would be obtained if other ethnicities in other community settings were investigated. Secondly, most of parents were mothers and the mother-child link in food intake is, supposedly, stronger than in father-child relation. Thirdly, an absolute dislike of food was not assessed. Austin et al 2011 aims at determining major trends in fat, protein and carbohydrate intake in adults and the association of these elements with the energy intake. The study was based on comparing two sets of data obtained from NHANES 1971-1975 and NHANES 2005-2006. For both NHANES, an interview was conducted during which participants were asked to recall their previous 24h dietary intake, including types of products and their quantities. Later, on the basis of their BMI, participants were classified into normal-weight, overweight and obese groups and total grams of fat, protein and carbohydrate were calculated with the help of Nutrient Composition Data Bank. The results of the study15 turned out to be the following: obesity prevalence increased from 11.9% to 33.4% in men and from 16.6% to 36.5% in women; energy intake from carbohydrates increased from 44.0% to 48.7%; energy from fat decreased from 36.6% to 33.7% and energy from protein decreased from 16.5% to 15.7%. These main trends were the same across normal-weight, overweight and obese groups of participants. From the results the authors have concluded that dietary interventions should focus on decreasing energy intake
  • 16. 16 by potentially substituting protein for carbohydrates or fat. The limitation of the study consisted in the fact that data were obtained by a cross-sectional survey and it was impossible to determine whether the assessed dietary patterns were the same throughout the entire participant’s life leading to the given weight status at the time of interview. Elbel et al 2011 conducts a natural experiment trying to find out whether fast-food mandatory calorie labeling will influence the food choice of children and adolescents. The study included analysis of surveys and receipts from two different cities under two conditions: after participants were not and then were provided with the calorie information while ordering food at the most popular fast food restaurants chains. The researchers16 obtained the following results: there were no significant differences in purchased calories before and after calorie labeling. 57% of participants did notice calorie labels after their introduction, but only 9% of them considered the information when ordering fast food. 72% of participants acknowledged that taste, not the calorie intake, was the most important factor in their meal selection, and that parents had some influence on their meal selection. The results have led to the conclusion that children and adolescents notice calorie information at similar rates with adults, but are less responsive to it. However, there is no significant evidence that labeling influences food choice. Results Overview Table Author and Year Study Type Class Quality Rating Sample Size Intervention Outcomes Limitations Pretlow 2011 Case Series D Ø 29,406 users; 41,535 messages and 93,787 replies No intervention Failure to cut down; need for pleasurable sensations from food; misery due to overeating Only pleasurable foods considered; do not know for sure if these include fat food, too Sampey et al 2011 RCT A + Nearly 8-9 rats per each of four 4 types of diet: common chow, low-fat, Metabolic alterations in certain groups: Difficult to conclude as to the role or
  • 17. 17 experimenta l groups high-fat diet, cafeteria food obesity, adipose inflammation mechanism of a specific food constituent (high-fat or high-sucrose) in weight gain associated with CAF diet Boggs et al 2011 Case Series D Ø 41,351 African American women No intervention Vegetable diet leads to less weight gain; meat diet – to more weight gain Use of food frequency questionnaires and self- reported measures of body size which require verification Giesen et al 2011 Time Series C + 178 students Providing information on calorie intake; price increase on calorie food Price increase results in less purchases of calorie food; calorie information interferes with taxing Limited number of participants; price conditions were not randomized Andreyeva et al 2011 Cohort Study B + 9760 children TV exposure to soft drink and fast food advertising TV exposure to soft drink and fast food advertising leads to bigger consumption of these products Survey measures based on children’s self-reports; no direct link between advertising and children’s body weight; lack of advertising data for children living outside top 55 designated marketing areas Anderson et al 2011 Cross- sec- tional study D Ø 4, 311 participants No intervention Frequency of fast food consumption is strongly associated with obesity Exclusion of people not using household telephones; nonresponse to telephone call Boyland et al 2011 Cohort Study B + 281 children Food and toys advertising on TV TV advertising enhances viewer’s food preferences The northwest of England Guendelm an et al 2011 RCT A + Experiment 1: 53 participants; Experiment 2: 51 participants Threat to American identity based on food preferences Asian Americans feeling threat to their identity opt for more unhealthy American food Not mentioned Fulkerson RCT A + 44 Obesity Obesity Limited power:
  • 18. 18 et al 2010 child/parent dyads prevention program: specific sessions on healthy lifestyle prevention program is feasible and well-accepted program based mostly on Caucasian and highly educated families, including those already eating frequent meals together Lanza et al 2012 Case Series D Ø 2 socio- economic “built environment s” No intervention Societal factors are important in health condition, especially as far as obesity is concerned Not mentioned Smith et al 2010 Cross- section al study D Ø 8,460 adults and 7,365 children Price increase on high- calorie food 20% increase could reduce calorie intake by 37 calories per day for the average adult and 43 calories per day for children The effect of tax may differ if beverages are consumed away from home and may depend on beverage companies and retailers’ strategy Currie et al 2010 Cohort study B + 3.06 million of children; 3 million of women with 3.5 million births Fast-food availability and proximity There is a significant effect of fast food restaurant proximity on the risk of obesity Possible measurement error Raynor et al 2011 Cross- section al study D Ø 135 parent/child pairs No intervention (Family-based weight control study) Changes in parent intake is important in helping overweight/ob ese children to also change dietary intake as far as healthy food is concerned Homogeneous sample of white families; most of parents were mothers; an absolute dislike of food was not assessed Austin et al 2011 Cross- section al study D + 9,769 adults (NHANES 1971-1975); 3,724 adults (NHANES 2005-2006) No intervention Obesity prevalence increased; energy from carbohydrates increased, but from fat and protein decreased Data were obtained by cross-sectional survey Elbel et al 2011 Before and after study D + 349 children and adolescents Labeling calorie fast food No significant evidence that labeling influences food choice Not mentioned
  • 19. 19 Discussion Evidence summery After the analysis of relevant articles concerning the problem of obesity, all of them agree at the point that this is an important and challenging problem, especially for U.S. citizens. Americans consume a large amount of unhealthy food,2-4, 7, 12, 13, 16 especially fast food and sweetened beverages. Having a high-calorie intake and, obviously, not that active lifestyle, the energy taken from the food is not entirely spent and, as a result, obesity develops. The fact is particularly dangerous in the case of children and adolescents2, 5, 6, 8, 16 and requires effective measures such as, for example, obesity prevention programs, 10 which, if planned thoroughly, may prove to be absolutely feasible and successful. Articles dedicated to discussing influence of TV exposure on children6, 8 also agree that this group of potential consumers is especially vulnerable: high level of watching food ads may lead to increase in unhealthy food consumption and, furthermore, to obesity. A number of articles stress the importance of family and community in general in providing a good example for their children.10, 11, 14 Eating behavior and main dietary patterns that the children have contact with in their everyday environment have a tremendous impact on the food they choose to consume. Thus, parents should fully realize that their positive example will foster healthy lifestyle among younger generations and vice versa. An interesting finding worth of attention is the fact that, according to some researchers,3, 15 it is not the high-fat food that contributes to obesity the most, as probably the majority of us thinks. Actually, so-called cafeteria diet3 , which consists of traditional snacks such as crackers, chips, processed meats, etc. is more harmful than, for example, a high-fat lard diet. This statement is also supported by the recent statistical data15 that energy intake increased from carbohydrates, but, in fact, decreased from fat and protein.
  • 20. 20 Despite the general agreement among the articles, there are some inconsistencies, too. For example, one group of researchers5 suggested that the tax ≥25% would make consumers buy less calorie-rich food. Such a conclusion was based on a natural experiment with quite limited number of participants. However, another group of researchers12 argued that the lower tax rate of only 20% might be similarly useful in reducing calorie intake. Their results were based on economic prediction approach relying on relation between price and demand in the market. Nobody knows, unfortunately, what the results would be under real-life conditions, if such a tax were applied to a wide range of products. Though all the articles were connected with the obesity problem, it is obvious that they dealt with it differently by studying it from different sides or within different groups of population. In short, the analyzed studies concentrated on the following ethnic, age and gender groups: children and adolescents,2, 6, 8, 11, 13, 16 African American women,4 , pregnant women,13 Asian Americans,9 families in general,10, 14 , adults, 4, 5, 7, 9, 13 and mixed large groups of population.12, 15 One study tried to develop a working obesity model for humans by con- ducting experiments with Wistar rats.3 The methodological base also varied from study to study. Generally speaking, the researches were based on already available large amount of data collected from databases or online sources,2, 7, 11, 12, 15 natural experiments4, 6, 13, 14, 16 and controlled experiments.3, 5, 8, 9, 10 But such a categorization is a very rough one. Obviously, data sample distribution is not the same as well, ranging from two socioeconomic environments,11 a couple of lab rats3 and nearly 100 participants to millions of participants.13 As far as outcome impact statement is concerned the following case is of interest. Some researchers were interested in finding out how providing calorie information influences the choice of food. 5, 16 However, they obtained slightly different results due to different interaction between the components of the study. Giesen et al 2011 focused on interaction
  • 21. 21 between calorie information and price increase, while Elbel et al 2011 concentrated on labeling itself. Thus, in the former study if no calorie information was provided, price increase resulted in decrease of calorie purchase, but if calorie information was provided, price increase did not result in decrease of calorie purchases. As we can see, the researchers succeeded in manipulating food purchases depending on labeling, though only with the help of tax increase. The latter study, on the other hand, not having taken into consideration any other factors except the very labeling, did not achieve any changes in the amount of fast food purchases, thus concluding that labeling did not significantly influence food choice. Conclusions Question: How does the high-fat American diet contribute to obesity? Preliminary Conclusion: Obesity within American population is connected with the high level of unhealthy food consumption. Generally speaking, the high rate of obesity prevalence among U.S. citizens may be explained by the following statements: • By tradition, Americans are used to fast food and other harmful types of food, rich in fat. This influence is even spread onto immigrants who want to vindicate their American identity • The given effect is further heightened by wide distribution and close proximity of fast food restaurants within some of the communities • There is a possibility of such a phenomenon as pleasurable food addiction • Cafeteria-diet is even more unhealthy than high-fat food • Vegetable/fruit dietary pattern is often avoided • Calorie labeling has little or no influence on opting for different type of food • Exposure to TV food advertising is responsible for increase in unhealthy food demand
  • 22. 22 • Families and whole communities play an important role in providing their children with bad example of consuming unhealthy food • Small number of feasible obesity prevention programs • Higher taxes on unhealthy food are not fully employed Conclusion Grading Table Strength of Evidence Elements Grade (I, II, III) Quality (scientific validity) Consistency (of findings across studies) Quantity (number of studies and subjects in studies) Clinical Impact (importance and magnitude of outcomes and effect) Generazibility (to population of interest)
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