Obesity is defined as excess fat on the human body. Obesity is measured using Body Mass Index (BMI) which is calculated by dividing weight (kg) by height squared (m^2). It is classified as between the rage of 25 and 30kg/m^2 on the BMI scale. Dyslipidemia, diabetes, hyperglycemia and cardiovascular diseases are all associated with high body fat levels. Globally, 1.3 billion people are classified as being either overweight or obese, which is an excessively high number and it needs to be reduced (Oussaada et al., 2019).
In relation to the Survey of Lifestyle, Attitudes and Nutrition in Ireland (SLAN, 2007) which consisted of face-to-face interviews of 10,000 participants. 967 adults took part in assessing their BMI, this was a very small proportion of participants and therefore the results do not give a reliable insight into the obesity levels as Ireland as a whole. From the data collected 25% of the population were classified as obese with 24% being men and 26% being females (Morgan et al., 2007, p.6). This is a high level of obesity for such a small county and for this reason this literate review was conducted in order to highlight the relative benefits of PA and diet in regard to obesity both in Ireland and abroad.
This literature review is targeted at assessing the information available on the benefits of PA and a healthy diet in reducing obesity levels and attempting to decrease the populations affected by this disease.
Main Content
Janssen et al., 2004 conducted research into the relationship between PA and diet with overweight and obesity. The results from the Health Behavioural in School-Aged Children Survey (HBSC) was required in order to get an appropriate sample of 11-16 year olds to be used in this study and to assess the desired fields. The HBSC is a cross-sectional study focused on youth behaviours and health. It has been implemented in 35 countries and the Canadian version was used for this study (Currie et al.,2004). The study undertaken by Janssen et al., 2004 included 5890 participants and their requirements such as height and weight were self-reported. Participants with a BMI of greater than 30kg/m^2 were categorized as obese. The participants were asked how regularly they eat certain healthy and unhealthy foods. PA levels were also questioned regarding if they reached 60 minutes of PA throughout a day(s) during the week. 31.7% of obese participants ate fruit daily compared to 36.3% of participants that were normal weight. There was no increase in the likelihood of obesity in relation to soft drink consumption with 36% of those classified as obese consuming soft drinks daily in comparison to 26.6% of normal weight individuals. Boys with a high consumption of potato chips and cake were less likely to be overweight or obese, similarly girls with a high intake of cakes and pastries were less likely to have a high BMI.
Overall, high PA levels were associated with low body weight. 28.5% of obese participants were active on one or less days of the week compared to 13.6% of those with a normal weight. No substantial affiliation existed between obesity and diet however, high PA levels resulted in low BMI compared to obese individuals who had low PA levels (Janssen et al., 2004).
Limitations
The data included in this study used self-reported heights and weights in order to calculate BMI for the participants. The amounts of foods eaten and levels of PA in the week was also self- reported by the participants, this raises questions about the validity of the study (Strauss et al., 1999). This report was provided on science direct which is a reliable database.
In a similar study, Winkvist et al., 2016 undertook an assessment of the diet, activity levels and obesity in 15-year olds in Western Sweden. This investigation consisted of 11,222 participants which was just under double the Janssen et al., 2004 total participant number. The Regional Ethics Committee granted ethical approval for the study, there was no mention of ethical approval in the first study. The questionnaire consisted of a variety of categories including their diet and PA levels, which will be the focus of this study. Height and weight measurements were self-reported and used to calculate BMI which was also similar to the first study. Portion size estimates were required as part of this study along with frequency of food intake. In relation to the recommended fruit and vegetable intake, girls had a higher chance of meeting this (49.5%) compared to boys (34.4%). Boys tended to be more physically active (64.3%) compared to girls (60.3%). When BMI was calculated for both genders 2.4% were classified as obese, with boys being the more prevalent sex. A bivariate test on the study was conducted which indicated that there was a 20% increase in the likelihood of overweight or obesity if a diet low in vegetables was consumed.
A diet low in vegetables indicated that there was a 20% increase in the likelihood of overweight and obesity after a bivariate test on the data was conducted. A lifestyle low in PA revealed that there was an increase in the chances of being obese (Winkvist et al., 2016)
This study consisted of self-reported data by means of a lifestyle questionnaire, which may lead in speculation of the reliability of the data. Portion sizes when reporting food intake which lead to the data being more accurate to studies that did not use this method. It was subjective to 15-year olds, which does not portray a wide insight into adolescent behaviours. However, the participant number was large which did give a detailed view of 15-year olds in Western Sweden and lead to a greater strength in study design. This can be used as a format to compare to other studies with adolescent same age group in different countries. Nutritional Journal… Cross-sectional
Mei et al., 2016 undertook a study to examine papers of Random Control Trials on primary school children. The interventions included were to investigate PA and BMI scores in comparison to a control group where no PA was required, 18 studies were included in the meta-analysis. The PA interventions were classified into less or greater then 100 minutes per week and the duration of the total intervention which varied from 1-2 years or greater than 2 years. Nutrition and diet were included in some of the interventions.
Overall, there was a 2.3kg/m^2 difference in BMI between the PA intervention group and the control group. Standardized Mean Difference (SMD) and a confidence interval of 90% was calculated throughout the study on the data. The group that participated in 30-100 minutes of PA received a SMD of 0.22 in contrast to 0.18 for completing over 100 minutes of exercise. There was a 0.19 kg/m^2 difference in BMI when a 2-year PA intervention took place.
Surprisingly, the group that took part in less than 100 minutes of PA reduced their BMI greater than the group that took part in over 100 minutes of PA, which was the opposite to the predicted results (Mei et al., 2016).
Racasens et al., 2019 investigated randomized control PA and nutrition intervention. A 2 year intervention took place in 2006-2008 which advertised the PA and diet, this was part of the AVall project (Llarggues et al., 2011). The 509 participants were primary school children born in the year 2000. The benefits of PA and healthy diet were advertised to students. Equipment was given to the intervention group to increase their PA levels and also positive guides on healthy eating was also given. Every week 3 hours were allocated to increase knowledge of living a healthy lifestyle through diet and exercise, throughout the 2 years. A control was used for means of comparison, where no PA or nutritional guidance was given. In 2006 data was obtained from 122 students from the control group and 156 from the intervention group.
Results were compared in relation to BMI that was recorded from the beginning of the trial to the BMI recorder in 2016. In 2006 the mean BMI was 16.4kn/m^2 this increased to 22.5kg/m^2 IN 2016, which was a 6.1kg/m^2 increase. The intervention group increased by 5.4kg/m^2 to over the 8 years from 16.9kg/m^2 to 22.3kg/m^2. BMI values were used to calculate weight statuses of the student over the 8 years. In the control group in 2006 the number of students classified as overweight or obese was 22.2% which increased to 27.9% in 2016. In relation to the intervention group 25.6% of the group were overweight or obese this decreased by 4.4% in 2016 to 21.2%. Participation in after school PA increased by 11% in the intervention group from 2006 to 2016 (Recasens at al., 2019).
This study consisted of an 8-year follow-up, providing a reliable insight into the long-term effects of the study. There was a small group of participants included in the study which does nit provide very reliable results. The intervention group at the start of the study had a higher BMI than the control group which was not ideal for the basis of the data. A high number of participants did not complete the follow up, which was a disadvantage to the study therefore decreasing numbers more. The teachers in the school had to be educated and trained in PA and nutrition in order to teach the students correctly.
In order to assess the impacts that PA causes to overweight and obese people, Kim et al., 2017 undertook an investigation to assess studies on these factors. A series of interventions were investigated to of aerobic exercise (AE) a 1.6kg decrease was found in body weight and a 2.2cm reduction in waist circumference. In relation to 12-month AE interventions a 1.7kg decrease in body weight was calculated and a 1.95cm reduction in waist circumference was identified (Thorogood et al., 2011). This shows how effective AE is in reducing body weight in obese populations, this PA needs to be continued after the intervention in order to maintain the weight loss. Willis et al., 2012 conducted interventions of AE and resistance training (RT) combined AE and RT displayed reductions in body weight in comparison to the RT group.
In conclusion, AE is an effective way of reducing body weight. RT does not reduce body weight however it improves body proportions by increasing muscle mass (Kin et al., 2017).
Burke et al., 2012 completed a 6-month Randomized Control Trial involving overweight 60 to 70 year olds. An intervention group was established with 248 participants. This group received information relating to PA and diet in the form of a booklet aimed at encouraging participants to improve on these aspects. They were also given equipment in order to increase their PA participation. The control group were asked to complete questionnaires at the same time as the intervention group. BMI and Waist to Hip Ratio (WHR) were self-reported at the beginning and end of the trial. No significant improvements were seen at the end of the 6 months in relation to BMI, however a 2.11cm reduction in WHR was observed in the intervention in contrast to the control group.
A small group of participants were included in this study which reduces the strength behind the study. The data recorded was self-reported which questions its validity. This report was provided on science direct which is a reliable database.
Summary
To summarise, it is evident from the discussed literature above that PA and diet both are effective at reducing overweight or obesity levels. The studies included incorporate different age groups- both young and old to see that any aged individual can benefit from a lifestyle high in PA and consume a balanced diet. The literature also includes studies from a variety of countries so that the data reported is not subjective. Meta-analysis and Randomized Control Trials are included in order to get a greater insight into the different approaches used to test the evidence behind the impacts PA and diet have on obesity.
Bibliography
Oussaads, S., van Galen, K., Cooiman, M., Kleinendorst, L., Hazebroek, E., van Haelst, M., Horst, K. and Serlie, M. (2019) The Pathogenesis of Obesity. Elsevier, 92 (1), pp.26-36.
Morgan, K., McGee, H., Watson, D., Perry, I., Barry, M., Shelly, E., Harrington, J., Molcho, M., Layte, R., Tully, N., van Lente, E., Ward, M., Lutomski, J., Conroy, R. and Brugha, R. (2007) Survey of Lifestyle, Attitudes and Nutrition in Ireland. Main Report. Dublin: Department of Health and Children. Available at: https://epubs.rcsi.ie/cgi/viewcontent.cgi?article=1002&context=psycholrep [Accessed 3 March 2019].
Janssen, I., Katzmarzyk, P., Boyce, W., King, M. and Pickett, W. (2004) Overweight and Obesity in Canadian Adolescents and their Associations with Dietary Habits and Physical Activity Patterns. Journal of Adolescent Health, 35(5), pp.360-367.
Strauss, R. (1999) Comparison of measured and self-reported weight and height in a cross-sectional sample of young adolescents. International Journal of Obesity and Related Metabolic Disorders, 23(1), pp.904-908.
Winkvist, A., Hulten, B., Kim, J., Johansson, I., Taren, K., Brisman, J. and Forslund, H. (2016) Dietary intake, leisure time activities and obesity among adolescents in Western Sweden: a cross-sectional study. Nutrition Journal, 15(41), pp.1-12.
Mei, H., Xiong, Y., Xie, S., Guo, S., Li, Y., Guo, B. and Zhang, J., (2016) The impact of long-term school based physical activity interventions on body mass index of primary school children- a mets7a analysis of randomized control trials. BMC Public Health, 16(1), pp.1-12.
Recasens, A., Xicola- Gormina, E., Manresa, J., Ullmo, P., Jensen, B., Franco, R., Suarez, A., Nadal, A., Vila, M., Recasens, I ., Perez, M., Castell, C. and Llargues, E. (2019) Impact of school-based nutrition and physical activity intervention on body mass index eight years after cessation of randomized control trial (AVall study). Clinical Nutrition.
Kim, B., Choi, D., Jung, C., Kang, S., Mok, J. and Kim, C. (2017) Obesity and Physical Activity. Journal of Obesity and Metabolic Syndrome, 26(1), pp.15-22.
Thorogood, A., Motillo, S., Shimony, A., Fillion, K., Joesph, L., Genest, J., Pilote, L., Poirier, P., Schiffrin, E. and Eisenberg, M. (2011) Isolated Aerobic Exercise and Weight loss: A systematic Review and Meta-Anlysis of Randomized Control Trials. The Americal Journal of Medicine, 124(8), pp.747-755.
Willis, L., Stentz, C., Bateman, L., Shields, A., Pinez, L., Ba;es, L., Houmard, J. and Kraus, W. (2012) Effects of aerobic and/or resistance training on body mass and fat mass in overweight or obese adults. Journal of Applied Physiology, 113(12), pp.1831-1837.