Do negative emotional factors have independent associations with excess adiposity?

1. Do negative emotional factors have independent associations with excess adiposity? ----------Xiyao Wang

4. Over the past three decades, the estimated percent of obese adults in the United States has more than doubled, increasing from 15% in 1976–1980 to 36% in 1999–2010 .Although epidemiologic studies typically define obesity as a body mass index(BMI)≥30 kg/m2 , other indicators of excess adiposity are available ,including waist circumference (WC) and waist-to-hip ratio(WHR). Regardless of the adiposity indicator used, excess adiposity confers elevated risk for other chronic medical conditions, such as coronary artery diseaseand type 2 diabetes , and obese individual shave higher mortality risk compared to their normal weight peers .

5. Although evidence suggests that many obesity-related health complications may be reversible when excess weight is lost ,studies have shown that 80% of individuals in obesity treatment programs are unsuccessful at maintaining long-term weight loss.

6. These figures highlight the importance of understanding and intervening on risk factors for excess adiposity in order to prevent obesity and its consequences.

7. Negative emotional factors as risk factors for obesity • Taken in isolation, depression, anxiety, and hostility/anger have been shown to predict obesity. It is unknown whether these negative emotional factors are associated with adiposity, independently of each other.

8. Although less research is available, investigators have also detected positive cross-sectional associations between hostility/anger and adiposity indicators . In their meta-analysis of studies examining the relationship between hostility and BMI and/or WHR, Bunde and Suls reported small Hedge's g effect sizes ranging from .15 to.25. Prospective evidence also suggests that hostility/anger predicts increases in continuous measures of adiposity over time .

9. odds ratio The odds ratio is a relative measure of risk, telling us how much more likely it is that someone who is exposed to the factor under study will develop the outcome as compared to someone who is not exposed. Odds are a way of presenting probabilities

11. Limitation A key limitation of the current literature is that depression ,anxiety, and hostility/anger are typically examined in isolation. Investigating the relationships between each negative emotional factor and adiposity indicators in separate studies is problematic because it ignores the moderate-to-high degree of overlap among these constructs. Consequence: studies examining only one negative emotional factor are unable to identify which of the negative emotional factors are independent determinants of excess adiposity.

12. Objective As the first step, the objective of this review was to determine whether negative emotional factors have independent associations with adiposity. The secondary objective was to provide specific recommendations for future studies in this area.

13. Contributions • First, it provides a rationale for determining the independent effects of emotional factors on adiposity. • Second, it supplies conceptual models for understanding the relationships among emotional factors and obesity. • Finally, it provides evidence as to which emotional factors may independently contribute to obesity development, uses this evidence to suggest which risk factor model best represents the emotional factors–obesity relationships, and offersspecific recommendations for future research.

14. Method • Definition and assessment of negative emotional factors • Definition and assessment of adiposity • Study selection criteria • Classification of studies

15. Definition and assessment of negative emotional factors • Depression, anxiety, and hostility/anger were chosen as the negative emotional factors, given that they are relatively stable over time represent a large proportion of the negative affectivity construct. • Have been examined in relation to indicators of adiposity • Acute affective states, such as those generated by an experimental manipulation, were not included as emotional factors in this review.

16. Definition and assessment of adiposity • Anthropometric techniques (e.g., BMI,WHR, andWC) • Body composition analysis techniques • Self-reported height and weight were used to calculate BMI were also included

17. Study selection criteria • Search strategy and terms • Inclusion and exclusion criteria

18. Search strategy and terms • depression :depression, depressive, dysthymia, major depression, dysphoria; • anxiety : anxiety, anxiety disorder, fear,phobia, worry • hostility/anger :hostility, anger, aggression • adiposity : adiposity, adipose, fat, obesity,obese, bodymass, bodymass index, waist circumference, abdominal diameter,waist to hip ratio, skinfolds, body composition, body density, dual energy X-ray absorptiometry, bioelectrical impedance,BOD POD, densitometry, hydrometry, hydrostatic weighing, and underwater weighing.

19. Inclusion and exclusion criteria • Inclusion: studies had to examine two or more emotional factors in relation to at least one indicator of adiposity (n=60).

20. Inclusion and exclusion criteria • Exclusion: • (1) the study did not conduct adjusted analyses • (2) the study evaluated the effect of an intervention • (3) the study examined patient, treatment-seeking, or pregnant samples without including a healthy or non-pregnant control group • (4) the study combined measures of different emotional factors(e.g., combined mood and anxiety diagnoses) • (5) the study assessed only state affect (i.e., emotions) • (6) the study measured adiposity only within a composite measure (e.g., the metabolic syndrome).

21. Data 3 prospective and 11 cross-sectional studies only 14 studies can be used

23. Classification of studie Results of each selected studies were reviewed to determine whether the negative emotional factors were associated with the adiposity indicator in unadjusted and adjusted analyses.

24. If a particular emotional factor remained associated with an adiposity indicator after adjustment for at least one other negative emotional factor (i.e., in the adjusted analyses), we considered this evidence that the emotional factor had an independent effect on adiposity. • if the relationship was no longer observed after controlling for another emotional factor, we viewed this as evidence that the negative emotional factor did not have an independent effect.

25. Results

26. This review contributes to the emotional factors–obesity literature by indicating that both depression and anxiety may have unique associations with excess adiposity when controlling for other negative emotional factors. Additional studies are required to determine whether hostility/anger is independently associated with adiposity. Collectively, our findings are most consistent with the independent model of interrelated risk factors shown in Fig. 1a. However, conflicting findings support further evaluation of the competing overlapping and proxy models (see Fig. 1b and c) and raise the possibility that a hybrid model may provide the best fit to the data.

27. Discussion • Advantages • Potential mechanisms underlying the emotional factors–obesity relationships • Interpretative considerations and limitations no existing study examined the association between all three negative emotional factors and an adiposity indicator using adjusted analyses. assessment of emotional factors and adiposity varied widely across studies. With regard to emotional factors, some investigations used continuous measures (e.g., depressive symptom severity), whereas others used categorical diagnostic variables (e.g., MDD diagnosis).

28. 反思 • 发现问题——统计方法质疑 • 实验材料的选择 • 不一定要自己做实验也可以是现成的实验数据并加以分析 • 严格筛选所用材料数据 • 实验方法的选择 • 综合考虑实验数据检测指标 • 当直接的实验方法不奏效是，是否能找到合适的替代方法，更科学的研究问题 • 后期讨论——辩证分析实验 • 数据数量、来源 • 对以后实验的作用

29. THANKS