***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Swimming may stimulate appetite and food intake but empirical data are lacking . This study examined appetite , food intake , and plasma acylated ghrelin responses to swimming .  Fourteen healthy males completed a swimming trial and a control trial in a r and om order . Sixty min after breakfast participants swam for 60 min and then rested for six hours . Participants rested throughout the control trial . During trials appetite was measured at 30 min intervals and acylated ghrelin was assessed periodically ( 0 , 1 , 2 , 3 , 4 , 6 , and 7.5 h. N = 10 ) . Appetite was suppressed during exercise before increasing in the hours after . Acylated ghrelin was suppressed during exercise . Swimming did not alter energy or macronutrient intake assessed at buffet meals ( total trial energy intake : control 9161 kJ , swimming 9749 kJ ) . These findings suggest that swimming stimulates appetite but indicate that acylated ghrelin and food intake are resistant to change in the hours afterwards The reason for high altitude anorexia is unclear but could involve alterations in the appetite hormones ghrelin and peptide YY ( PYY ) . This study examined the effect of resting and exercising in hypoxia ( 12.7 % O(2 ) ; ∼4,000 m ) on appetite , energy intake , and plasma concentrations of acylated ghrelin and PYY . Ten healthy males completed four , 7-h trials in an environmental chamber in a r and om order . The four trials were control-normoxia , control-hypoxia , exercise-normoxia , and exercise-hypoxia . During exercise trials , participants ran for 60 min at 70 % of altitude-specific maximal oxygen consumption ( Vo(2max ) ) and then rested . Participants rested throughout control trials . A st and ardized meal was consumed at 2 h and an ad libitum buffet meal at 5.5 h. Area under the curve values for hunger ( assessed using visual analog scales ) tended to be lower during hypoxic trials than normoxic trials ( repeated- measures ANOVA , P = 0.07 ) . Ad libitum energy intake was lower ( P = 0.001 ) in hypoxia ( 5,291 ± 2,189 kJ ) than normoxia ( 7,718 ± 2,356 kJ ; means ± SD ) . Mean plasma acylated ghrelin concentrations were lower in hypoxia than normoxia ( 82 ± 66 vs. 100 ± 69 pg/ml ; P = 0.005 ) while PYY concentrations tended to be higher in normoxia ( 32 ± 4 vs. 30 ± 3 pmol/l ; P = 0.059 ) . Exercise suppressed hunger and acylated ghrelin and increased PYY but did not influence ad libitum energy intake . These findings confirm that hypoxia suppresses hunger and food intake . Further research is required to determine if decreased concentrations of acylated ghrelin orchestrate this suppression BACKGROUND The performance of exercise while immersed in cold water has been shown to influence energy intake in the subsequent meal . However , the effect of ambient temperature during l and -based exercise is not known . OBJECTIVES Our aims were to investigate the effect of exercise performed in the heat on energy intake in the subsequent meal and to determine concentrations of circulating appetite-related hormones . DESIGN In a r and omized , counterbalanced design , 11 active male participants completed 3 experimental trials in a fasted state : exercise in the heat ( 36 degrees C ) , exercise in a neutral temperature ( 25 degrees C ) , and a resting control ( 25 degrees C ) . The exercise trials consisted of treadmill running for 40 min at 70 % VO(2peak ) . After each trial , participants were presented with a buffet-type breakfast of precisely known quantity and nutrient composition , which they could consume ad libitum . RESULTS Energy intake was greater after exercise in the neutral temperature compared with the control ( P = 0.021 ) but was similar between exercise in the heat and the control and between the 2 exercise trials . When accounting for the excess energy expended during exercise , relative energy intake during exercise in the heat was lower than the control ( P = 0.002 ) but was similar between exercise in the neutral temperature and the control and between exercise in the heat and in the neutral temperature . The lower relative energy intake after exercise in the heat was associated with an elevated tympanic temperature and circulating concentrations of peptide YY ( P < 0.05 ) . CONCLUSION Exercise in a neutral environmental temperature is associated with higher energy intake in the subsequent meal compared with a control , whereas exercise in the heat is not Resistance ( muscle strengthening ) exercise is a key component of exercise recommendations for weight control , yet very little is known about the effects of resistance exercise on appetite . We investigated the effects of resistance and aerobic exercise on hunger and circulating levels of the gut hormones acylated ghrelin and peptide YY ( PYY ) .  Eleven healthy male students : age 21.1 + /- 0.3 yr , body mass index 23.1 + /- 0.4 kg/m(2 ) , maximum oxygen uptake 62.1 + /- 1.8 ml.kg(-1).min(-1 ) ( means + /- SE ) undertook three , 8-h trials , 1 ) resistance exercise : a 90-min free weight lifting session followed by a 6.5-h rest period , 2 ) aerobic exercise : a 60-min run followed by a 7-h rest period , 3 ) control : an 8-h rest , in a r and omized crossover design . Meals were provided 2 and 5 h into each trial . Hunger ratings and plasma concentrations of acylated ghrelin and PYY were measured throughout . Two-way ANOVA revealed significant ( P < 0.05 ) interaction effects for hunger , acylated ghrelin , and PYY , indicating suppressed hunger and acylated ghrelin during aerobic and resistance exercise and increased PYY during aerobic exercise . A significant trial effect was observed for PYY , indicating higher concentrations on the aerobic exercise trial than the other trials ( 8 h area under the curve : control 1,411 + /- 110 , resistance 1,381 + /- 97 , aerobic 1,750 + /- 170 pg/ml 8 h ) . These findings suggest ghrelin and PYY may regulate appetite during and after exercise , but further research is required to establish whether exercise-induced changes in ghrelin and PYY influence subsequent food intake BACKGROUND The gut hormone fragment peptide YY3 - 36 ( PYY ) reduces appetite and food intake when infused into subjects of normal weight . In common with the adipocyte hormone leptin , PYY reduces food intake by modulating appetite circuits in the hypothalamus . However , in obesity there is a marked resistance to the action of leptin , which greatly limits its therapeutic effectiveness . We investigated whether obese subjects were also resistant to the anorectic effects of PYY . METHODS We compared the effects of PYY infusion on appetite and food intake in 12 obese and 12 lean subjects in a double-blind , placebo-controlled , crossover study . The plasma levels of PYY , ghrelin , leptin , and insulin were also determined . RESULTS Caloric intake during a buffet lunch offered two hours after the infusion of PYY was decreased by 30 percent in the obese subjects ( P<0.001 ) and 31 percent in the lean subjects ( P<0.001 ) . PYY infusion also caused a significant decrease in the cumulative 24-hour caloric intake in both obese and lean subjects . PYY infusion reduced plasma levels of the appetite-stimulatory hormone ghrelin . Endogenous fasting and postpr and ial levels of PYY  were significantly lower in obese subjects ( the mean [ + /-SE ] fasting PYY levels were 10.2+/-0.7 pmol per liter in the obese group and 16.9+/-0.8 pmol per liter in the lean group , P<0.001 ) . Furthermore , the fasting PYY levels correlated negatively with the body-mass index ( r = -0.84 , P<0.001 ) . CONCLUSIONS We found that obese subjects were not resistant to the anorectic effects of PYY . Endogenous PYY levels were low in the obese subjects , suggesting that PYY deficiency may contribute to the pathogenesis of obesity This study investigated the effects of a long bout of aerobic exercise on  hunger and energy intake and circulating levels of leptin and acylated ghrelin .  Ten healthy male subjects undertook two , 4 h trials in a r and omized crossover design . In the exercise trial subjects ran for 105 min at 50 % of maximal oxygen uptake and the last 15 min at 70 % of maximal oxygen uptake followed by a 120 min rest period . In the control trial , subjects rested for 4 h. Subjects consumed a buffet test meal at 180 min during each trial . Hunger ratings , acylated ghrelin , leptin , glucose and insulin concentrations were measured at 0 , 1 , 2 , 3 and 4 h. No differences were found at baseline values for hunger , acylated ghrelin , leptin , insulin and glucose for both trials ( p > 0.05 ) . The estimated energy expenditure of the exercise trial was 1550 ± 136 kcal . Exercise did not change subsequent absolute energy intake , but produced a significant decrease ( p < 0.05 ) in relative energy intake . A two-way ANOVA revealed a significant ( p < 0 . 05 ) interaction effect for hunger and acylated ghrelin . In conclusion , this exercise regimen had a positive effect on reducing appetite which is related to reduced acylated ghrelin responses over time . This finding lends support for a role of exercise in weight management . Key pointsPhysical exercise is a strategy used to counteract obesity , since it lowers the energetic balance by increasing energy expenditure . However , because any energy expended in exercise elevates the intensity of hunger and drives food consumption , it is pertinent to ask how effective exercise could be in helping people to lose weight or to prevent weight gain . The effects of exercise  on hunger sensations and food intake are fairly controversial and depend on the intensity and duration of exercise.120 min prolonged treadmill exercise with mix intensity , temporarily decreased hunger sensations , acylated ghrelin and relative energy intake . Variations in exercise intensity should theoretically be a useful means of weight loss Exercise is recommended by public health agencies for weight management ; however , the role of exercise is generally considered secondary to energy restriction . Few studies exist that have verified completion of exercise , measured the energy expenditure of exercise , and prescribed exercise with equivalent energy expenditure across individuals and genders . Objective The objective of this study was to evaluate aerobic exercise , without energy restriction , on weight loss in sedentary overweight and obese men and women . Design and Methods This investigation was a r and omized , controlled , efficacy trial in 141 overweight and obese participants ( body mass index , 31.0 ± 4.6 kg/m2 ; age 22.6 ± 3.9 years ) . Participants were r and omized ( 2:2:1 ratio ) to exercise at either 400 kcal/session or 600 kcal/session or to a non-exercise control . Exercise was supervised , 5 days/week , for 10 months . All participants were instructed to maintain usual ad libitum diets . Due to the efficacy design , completion of ≥ 90 % of exercise sessions was an a priori definition of per protocol , and these participants were included in the analysis . Results Weight loss from baseline to 10 months for the 400 and 600 kcal/session groups was 3.9 ± 4.9 kg ( 4.3 % ) and 5.2 ± 5.6 kg ( 5.7 % ) , respectively compared to weight gain for controls of 0.5 ± 3.5 kg ( 0.5 % ) ( p<0.05 ) . Differences for weight loss from baseline to 10 months between the exercise groups and differences between men and women within groups were not statistically significant . Conclusions Supervised exercise , with equivalent energy expenditure , results in clinical ly significant weight loss with no significant difference between men and women Ghrelin is a recently identified endogenous lig and for the growth hormone secretagogue receptor . It is synthesized predominantly in the stomach and found in the circulation of healthy humans . Ghrelin has been shown to promote increased food intake , weight gain and adiposity in rodents . The effect of ghrelin on appetite and food intake in man has not been determined . We investigated the effects of intravenous ghrelin ( 5.0 pmol/kg/min ) or saline infusion on appetite and food intake in a r and omised double-blind cross-over study in nine healthy volunteers . There was a clear-cut increase in energy consumed by every individual from a free-choice buffet ( mean increase 28 + /- 3.9 % , p<0.001 ) during ghrelin compared with saline infusion . Visual analogue scores for appetite were greater during ghrelin compared to saline infusion . Ghrelin had no effect on gastric emptying as assessed by the paracetamol absorption test . Ghrelin is the first circulating hormone demonstrated to stimulate food intake in man . Endogenous ghrelin is a potentially important new regulator of the complex systems controlling food intake and body weight This study 
    Output:
    
No moderator variables were observed to moderate the variability among the studies assessing acylated ghrelin and PYY .
Conclusions An acute bout of exercise may influence appetite by suppressing levels of acylated ghrelin while simultaneously increasing levels of PYY , GLP-1 and PP , which may contribute to alterations in food and drink intake after acute exercise .