the number of men and women worldwide who identify as lesbian , gay , or bisexual ( lgb ) has increased in recent years . according to a survey undertaken in 2011 by the williams institute at the ucla school of law , approximately 9 million people ( 3.5% of adults ) in the united states identify as lgb and an additional 0.3% of adults identify as transgender ( 1 ) . in 2003 , a study on australia reported that among adults aged 1659 , 1.6% and 0.9% of males identified as gay and bi - sexual , respectively , and 0.8% and 1.4% of females identified as lesbian and bisexual , respectively ( 2 ) . in denmark in 1992 , 2.7% of adult men and women reported having had same - sex sexual experiences ( 3 ) . in france in 1992 , 4.1% of men and 2.6% of women reported at least one same - sex sexual experience during their lifetime ( 4 ) . in ireland in 2006 , 2.7% of men and 1.2% of women identified as either homosexual or bisexual ( 5 ) , while in a 2003 norwegian survey , 12% of respondents reported having had a same - sex sexual experience ( 6 ) , and 6.1% of people surveyed in the united kingdom in 1992 had had a same - sex sexual experience ( 7 ) . in summary , the number of men and women worldwide who identify as lesbian , gay , or bisexual ( lgb ) has increased in recent years , with up to 12% of respondents reporting having engaged in same - sex sexual activity ( 1  7 ) . locally , even though statistics for the lgbt population can not be determined for certain korean cultures , of a sample of 1,748 adolescents in south korea , 12.7% had problems with their gender identity ( 8) . a number of studies have shown higher rates of diseases such as hiv / aids among the lgb population ( 911 ) , as well as a higher prevalence of asthma ( 12 ) , obesity ( 13 ) , and poor health behavior , indicating a relationship between this group s atypical sexual orientation and health - related lifestyle ( 1415 ) . for this and other reasons , however , there is currently almost no research in south korea on the prevalence of lgb identity and sexual behavior , meaning that the korean government has no information regarding possible public health concerns among the lgb population . therefore , the purpose of the present study was to determine whether lifestyle - related factors , including physical activity ( pa ) , differ between lesbian , gay , bisexual , and heterosexual korean adolescents . the 8 korea youth risk behavior web - based survey ( kyrbws - viii ) is an annual epidemio - logical and cross - sectional study that assesses the public health of korean adolescents . it uses a complex sample design of 43 clustering techniques , 129 stratification techniques , and multistage sampling to cover all of south korea while limiting the sample size to a manageable size : 400 middle schools and 400 high schools . all of the details regarding the data collection procedure have been described by the ministry of education , science , and technology , the ministry of health and welfare , and the korea centers for disease control and prevention ( 16 ) . this survey has well - established validity and reliability for this population ( 1718 ) . in the kyrbws - viii , students are assigned unique identification numbers by their classroom instructors , and then access the survey web page using these numbers . on the web page , they are asked if they are willing to participate ; students who choose to participate complete the questionnaire at their schools anonymously . because the kyrbws - viii does not collect any private information ( e.g. , students names , social security numbers , school names , telephone numbers , or home addresses ) , ethical approval was not required . the overall response rate for participation in the kyrbws - viii was 96.4% ( 74,186 out of 76,980 students ; 38,221 males and 35,965 females ) . however , only 11,829 of these 74,186 participants provided enough information about their romantic and sexual behavior to be categorized as gay , lesbian , bisexual , or heterosexual . sexual identity was evaluated using the item  select all of the following items that you have experienced . kissing and fondling someone of the opposite sex ,     sexual intercourse with someone of the opposite sex , kissing and fondling someone of the same sex ,     sexual intercourse with someone of the same sex , respondents who responded  yes  to only   or   ( i.e. , respondents who reported sexual or romantic behavior with people of the same sex only ) were categorized as homosexual ( gay or lesbian ) , respondents who responded yes  to both   or   and   or   ( i.e. , respondents who reported sexual or romantic behavior with people of both sexes ) were categorized as bisexual , and respondents who responded yes  to only   or   ( i.e. , respondents who reported sexual or romantic behavior with people of the opposite sex only ) were categorized as heterosexual . the subjects demographic characteristics subjects who reported that they had never engaged in sexual or romantic behavior ( responding  yes  to ) , or who reported only experiences of sexual violence ( responding  yes  to   or ) were excluded , as these items provided no information on sexual identity . using these criteria , males were divided into gay ( n = 323 ) , bisexual ( n = 243 ) , and heterosexual ( n = 6,501 ) groups , and females were divided into lesbian ( n = 208 ) , bisexual ( n = 113 ) , and heterosexual ( n = 4,441 ; table 1 ) groups . the data were then analyzed according to the groups sexual orientation for any significant relationships with certain key lifestyle behaviors : smoking cigarettes , drinking alcohol , eating breakfast , mental stress , and exercise ( vigorous , moderate , muscular strength exercises and walking at least 10 minutes per week ) through the kyrbws - viii . possible responses to these items are given as follows . frequency of vigorous pa , frequency of moderate pa , and frequency of muscular strength exercises per week were 1 =  never ,  2 =  once ,  3 = 5 =  four times  , and 6 =  five times or more . vigorous pa included activities such as digging , aerobics , heavy lifting , or fast cycling ; moderate pa included activities such as cycling at a regular pace , carrying light loads , or playing doubles tennis ; and muscular strength exercises included activities such as sit - ups , push - ups , and weight lifting or weight training . frequency of smoking and frequency of drinking per month had possible responses of 1 =  never ,  2 = 2029 days ,  and 7 =  every day  for . for frequency of breakfast consumption and frequency of walking at least 10 minutes per week , response options included 1 =  never ,  2 =  once ,  3 = twice ,  4 =  three times ,  5 =  4 times , 6 =  5 times ,  7 =  6 times ,  and 8 =  every day . finally , self - reported mental stress was assessed using responses of 1 =  very high ,  2 =  high ,  3 =  normal , one - way analysis of variance ( anova ) was used to identify differences in lifestyle factors , especially physical activity , among the three sexual identity groups ( homosexual [ gay or lesbian ] , bisexual , and heterosexual ) . the analyses were performed using spss version 18.0 ( chicago , il , usa ) and statistical significance was set at p < 0.05 . all study results are given as the mean  standard deviation or number ( % ) . sexual identity was evaluated using the item  select all of the following items that you have experienced . possible responses were :    none of these ,     kissing and fondling someone of the opposite sex ,     sexual intercourse with someone of the opposite sex ,     kissing and fondling someone of the same sex ,     sexual intercourse with someone of the same sex , respondents who responded  yes  to only   or   ( i.e. , respondents who reported sexual or romantic behavior with people of the same sex only ) were categorized as homosexual ( gay or lesbian ) , respondents who responded  yes  to both   or   and   or   ( i.e. , respondents who reported sexual or romantic behavior with people of both sexes ) were categorized as bisexual , and respondents who responded  yes  to only   or   ( i.e. , respondents who reported sexual or romantic behavior with people of the opposite sex only ) were categorized as heterosexual . the subjects demographic characteristics subjects who reported that they had never engaged in sexual or romantic behavior ( responding  yes  to ) , or who reported only experiences of sexual violence ( responding  yes  to   or ) were excluded , as these items provided no information on sexual identity . using these criteria , males were divided into gay ( n = 323 ) , bisexual ( n = 243 ) , and heterosexual ( n = 6,501 ) groups , and females were divided into lesbian ( n = 208 ) , bisexual ( n = 113 ) , and heterosexual ( n = 4,441 ; table 1 ) groups . the data were then analyzed according to the groups sexual orientation for any significant relationships with certain key lifestyle behaviors : smoking cigarettes , drinking alcohol , eating breakfast , mental stress , and exercise ( vigorous , moderate , muscular strength exercises and walking at least 10 minutes per week ) through the kyrbws - viii . possible responses to these items are given as follows . frequency of vigorous pa , frequency of moderate pa , and frequency of muscular strength exercises per week were 1 =  never ,  2 =  once ,  3 = twice ,  4 =  three times ,  5 =  four times  , and 6 =  five times or more . vigorous pa included activities such as digging , aerobics , heavy lifting , or fast cycling ; moderate pa included activities such as cycling at a regular pace , carrying light loads , or playing doubles tennis ; and muscular strength exercises included activities such as sit - ups , push - ups , and weight lifting or weight training . frequency of smoking and frequency of drinking per month had possible responses of 1 =  never ,  2 = 1019 days ,  6 =  2029 days ,  and 7 =  every day  for . for frequency of breakfast consumption and frequency of walking at least 10 minutes per week , response options included 1 =  never ,  2 = twice ,  4 =  three times ,  5 =  4 times ,  6 =  5 times ,  7 =  6 times ,  and 8 =  every day . finally , self - reported mental stress was assessed using responses of 1 =  very high ,  2 =  high ,  3 =  normal , one - way analysis of variance ( anova ) was used to identify differences in lifestyle factors , especially physical activity , among the three sexual identity groups ( homosexual [ gay or lesbian ] , bisexual , and heterosexual ) . the analyses were performed using spss version 18.0 ( chicago , il , usa ) and statistical significance was set at p < 0.05 . all study results are given as the mean  standard deviation or number ( % ) . the differences in lifestyle factors , especially physical activity , among the sexual identity groups are shown in table 2 . using one - way anova , we found that males showed significant differences by sexual identity group for frequency of smoking ( p = 0.029 ) , alcohol consumption ( p < 0.001 ) , muscular strength exercises ( p = 0.020 ) , and walking for at least 10 minutes ( p < 0.001 ) . post - hoc test indicated that gay males performed muscular strength exercises less frequently ( p < 0.05 ) and walked for at least 10 minutes less frequently ( p < 0.001 ) than heterosexual males . bi - sexual males consumed alcohol more frequently ( p < 0.001 ) and walked for at least 10 minutes less frequently ( p < 0.001 ) than heterosexual males . we also found , again using one - way anova , significant differences among females according to sexual identity group for frequency of smoking ( p < 0.001 ) , alcohol consumption ( p < 0.001 ) , vigorous pa ( p < 0.001 ) , moderate pa ( p < 0.001 ) , and muscular strength exercises ( p < 0.001 ) . there were also significant inter - group differences for self - reported mental stress ( p < 0.001 ) . post - hoc test showed that lesbian females reported more frequent vigorous pa ( p < 0.001 ) , moderate pa ( p < 0.001 ) , and muscular strength exercises ( p bisexual females engaged more frequently in smoking ( p < 0.001 ) , alcohol consumption ( p < 0.001 ) , vigorous pa ( p < 0.001 ) , moderate pa ( p < 0.001 ) , and muscular strength exercises ( p < 0.001 ) than did heterosexual females , in addition to higher self - reported mental stress ( p < 0.001 ) . this study examined whether there were differences in lifestyle factors by sexual orientation in korean adolescents . the most notable finding in the current study was that 887 adolescents ( 7.5% of the sample ) had some same - sex romantic or sexual experience , such as kissing , fondling , or sex . this statistic indicates that the lgb adolescent population in korea is larger than that of many other countries that were surveyed ( 9 ) . this comparably large lgb population may pose a public health risk in terms of sexually transmitted diseases . for this reason , we recommend that the korean government put into place school- and community - based programs for preventing social and health problems in the lgb community . the differences in lifestyle factors among the sexual identity groups prior studies have shown that gay and bisexual men have poorer general and mental health ( 9 ) , higher rates of smoking ( 19 ) and higher rates of alcohol use ( 20 ) than do heterosexual men . studies have also indicated that lesbians and bisexual women have poorer overall and mental health ( 13 ) , higher rates of smoking ( 21  22 ) , and higher rates of alcohol use ( 2324 ) . the results of the present study support these previous findings , in that gays , lesbians , and bisexual adolescents of both genders had higher rates of smoking and alcohol consumption than heterosexual adolescents did . however , although gay and bisexual males reported lower rates of muscular strength exercises and walking than their heterosexual counterparts , which might be indicative of poorer physical health , lesbians and bisexual females reported higher rates of vigorous pa , moderate pa , and muscular strength exercises than did their heterosexual counterparts , which might be indicative of better physical health . although the kyrbws - viii did not gather any information that might help us to better understand the reason for this difference , we hypothesize that this might be because lesbians may tend to assume male roles or lifestyles , leading lesbians and bisexual females to engage in more physical activities than heterosexual females . this study is limited in that the kyrbws - viii was a cross - sectional , retrospective cohort study ; as a result , we can not make any statements regarding causality . furthermore , although sexuality in adolescence may remain consistent throughout the lifespan , it is well known that sexual orientation in childhood and adolescence is not likely to persist into adulthood . therefore , findings from this study can not be generalized to the adult population in korea . moreover , since only participants who met the criteria for inclusion took part in the survey , findings from this study can not be generalized to the entire youth population in south korea . however , as the first national study on the lifestyle behaviors of the adolescent lgb population in south korea , we believe that this study will both encourage additional inquiry in this area and provide valuable information to promote the public health of this population . an additional limitation could be the fact that , at such a young age and with so little sexual experience , the sexual experiences reported by participants may not reflect their true , respective sexual orientations . we concluded that gay , lesbian , and bisexual males and females fare poorly with regard to healthy lifestyle behaviors , as compared to their heterosexual peers . , we suggest that efforts be undertaken by schools and communities to modify and prevent unsuitable lifestyle behaviors among lgb adolescents , using social and health education programs that specifically target this group . ethical issues ( including plagiarism , informed consent , misconduct , data fabrication and/or falsification , double publication and/or submission , redundancy , etc ) have been completely observed by the authors .
abstractbackgroundthe purpose of the present study was to examine differences in lifestyle factors such as physical activity among homosexual ( gay or lesbian ) , bisexual , and heterosexual korean adolescents.methodsthe sample consisted of 74,186 adolescents from grades 712 ( ages 1218 ) who participated in the 8th annual korea youth risk behavior web - based survey in 2012 . 
 of this sample , only 11,829 provided enough information regarding their romantic and sexual experiences to define them as gay , lesbian , bisexual , or heterosexual . from this information , 
 males were divided into gay ( n = 323 ) , bisexual ( n = 243 ) , and heterosexual ( n = 6,501 ) groups , and females were divided into lesbian ( n = 208 ) , bisexual ( n = 113 ) , and heterosexual ( n = 4,441 ) groups . 
 differences in lifestyle factors according to sexual orientation were analyzed using one - way analysis of variance.resultsmales showed significant differences by sexual orientation group in terms of frequency of smoking ( p = 0.029 ) , alcohol consumption ( p < 0.001 ) , muscular strength exercises ( p = 0.020 ) , and walking for at least 10 minutes per week ( p < 0.001 ) . 
 females showed significant differences by sexual orientation group in terms of frequency of smoking ( p < 0.001 ) , alcohol consumption ( p 
 < 0.001 ) , vigorous physical exercise ( p 
 < 0.001 ) , moderate physical exercise ( p 
 < 0.001 ) , and muscular strength exercises ( p < 
 0.001 ) , as well as for self - reported mental stress ( p < 0.001).conclusionwe concluded those gay and bisexual males and lesbian and bisexual females had significant lifestyle differences as compared with heterosexual adolescents . 
 this effect was stronger for females than for males .