Effects of exercise and restrained eating behaviour on appetite control

Impact of physical activity on caloric and macronutrient intake in children and adolescents: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Physical activity is widely promoted to maintain and improve health across all ages. Investigating how physical activity affects subsequent food intake provides insight into the factors that contribute to maintaining energy balance and effective weight management.

OBJECTIVE

This systematic review and meta-analysis summarizes the evidence on the effect of acute physical activity on subsequent food intake in children and adolescents.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA) were applied. Randomized controlled trials (RCTs) objectively measuring post-exercise energy intake in children and adolescents aged 5 to 18 years were included. Studies with self-reported food intake were excluded. The databases PubMed, Web of Science and Cochrane Library were searched for RCTs, and the data were summarized at a qualitative and quantitative level. Version 2 of the Cochrane risk-of-bias tool for randomized trials was used to assess risk of bias. Changes in energy intake were examined with random effects meta-analysis. (PROSPERO: CRD42022324259).

RESULTS

Out of 9582 studies, 22 RCTs with cross-over design remained eligible for meta-analysis. The primary outcome was post-intervention energy intake up to the next 24 h. Heterogeneity of studies was moderate, with an I2 of 57%. The median (interquartile range, IQR) energy expended while exercising was 240 (158) kcal. Meta-analysis of 41 study arms (exercise n = 780 and control n = 478) showed no differences in total energy intake between the exercise and control group with a mean difference MD = 23.31 [-27.54, 74.15] kcal. No subgroup differences were found. Macronutrient intake and appetite sensations where not substantially affected.

CONCLUSION

Engaging in exercise is a suitable means of raising activity-induced energy expenditure, without causing any noticeable changes in food intake or hunger within a single day.

Physical activity habits prevent psychological distress in female academic students: The multiple mediating role of physical and psychosocial parameters

Background

Psychological distress is recognised as the most common mental health difficulty in emerging adult (18-to-24-year-old) female academic students. This study aimed to test a novel model positing physical activity habits as a protective factor for psychological distress through the mediating role of physical and psychological parameters. Adherence to the Mediterranean diet and self-reported physical health status were included as physical parameters. Self-reported psychological health status and time spent on leisure activities were the psychological parameters considered.

Method

Data were collected between April and May 2021. Correlation analyses and a multiple mediation model were computed on 411 online questionnaires filled out by 18-to-24-year-old female students from the University of blind (Italy).

Results

The multiple indirect effects were significant (β = -0.088; p < 0.001). This means that physical activity habits reduce psychological distress through high adherence to the Mediterranean diet, a good self-assessment of one's physical and psychological health status, and more time spent on leisure activities outdoors, with friends, and with family members.

Conclusions

Results show that academic policies should be adopted so as to design physical activity programmes that may improve the students' healthy behaviours and social interactions, which, in turn, mitigate the detrimental effects of psychological distress.

Eating Behaviour among University Students: Relationships with Age, Socioeconomic Status, Physical Activity, Body Mass Index, Waist-to-Height Ratio and Social Desirability

Eating behaviour is of particular interest for research focusing on body weight status. However, little is known about the relationships of certain factors, especially social desirability, with self-reported eating behaviour such as cognitive restraint, uncontrolled eating, and emotional eating among young adult males and females. This study aimed to evaluate the relationships between eating behaviour and age, socioeconomic status (SES), physical activity (PA), body mass index (BMI), waist-to-height ratio (WHtR), and social desirability among university students. A cross-sectional study was conducted among 353 university students (59.2% females). Eating behaviour was assessed using the 13-item Three-Factor Eating Questionnaire (TFEQ-13). SES and PA were determined using self-reporting, and the Marlowe–Crowne Social Desirability Scale assessed social desirability. BMI and WHtR were calculated based on measured parameters. Associations between self-reported eating behaviour and other variables were assessed using Pearson’s correlation coefficient and multivariate general linear models. Cognitive restraint was positively correlated with BMI and WHtR in both males (r = 0.174, P = 0.036 and r = 0.194, P = 0.020, respectively) and females (r = 0.239, P < 0.001 and r = 0.165, P = 0.017, respectively), and emotional eating was positively correlated with BMI among females (r = 0.184, P = 0.008). Social desirability was negatively correlated with uncontrolled eating (r = −0.287, P < 0.001) and emotional eating (r = −0.301, P < 0.001) among females. There were no significant correlations between eating behaviour and age or socioeconomic status (P > 0.05). Multivariate analysis showed that, among males, PA had a main effect on emotional eating (ηp² = 0.044, F = 6.276, P = 0.013). Among females, cognitive restraint was positively associated with PA (ηp² = 0.034, F = 7.127, P = 0.008) and BMI (ηp² = 0.038, F = 7.959, P = 0.005), and emotional eating with BMI (ηp² = 0.032, F = 6.638, P = 0.011). Social desirability had the highest main effect on eating behaviour among females, being negatively associated with uncontrolled eating (ηp² = 0.077, F = 16.754, P < 0.001) and emotional eating (ηp² = 0.082, F = 18.046, P < 0.001). This study showed that PA, BMI, WHtR, and social desirability were associated with self-reported eating behaviour among university students. Social desirability bias should be considered when evaluating uncontrolled eating and emotional eating among females.

Restrained eating in Lebanese adolescents: scale validation and correlates

BACKGROUND

Restrained eating disorder is prevalent worldwide across both ethnic and different cultural groups, and most importantly within the adolescent population. Additionally, comorbidities of restrained eating present a large burden on both physical and mental health of individuals. Moreover, literature is relatively scarce in Arab countries regarding eating disorders, let alone restrained eating, and among adolescent populations; hence, the aim of this study was to (1) validate the Dutch Restrained Eating Scale in a sample of Lebanese adolescents and (2) assess factors correlated with restrained eating (RE), while taking body dissatisfaction as a moderator between body mass index (BMI) and RE.

METHODS

This cross-sectional study, conducted between May and June 2020 during the lockdown period imposed by the Lebanese government, included 614 adolescents aged between 15 and 18 years from all Lebanese governorates (mean age of 16.66 ± 1.01 years). The scales used were: Dutch Restrained Eating Scale, body dissatisfaction subscale of the Eating Disorder Inventory-Second version, Rosenberg Self-Esteem Scale, Beirut Distress Scale (for psychological distress), Hamilton Anxiety Rating Scale and Patient Health Questionnaire (for depression).

RESULTS

The factor analysis yielded a one-factor solution with Eigen values > 1 (variance explained = 59.65 %; α_Cronbach = 0.924). Female gender (B = 0.19), higher BMI (B = 0.49), higher physical activity index (B = 0.17), following a diet to lose weight (B = 0.26), starving oneself to lose weight (B = 0.13), more body dissatisfaction (B = 1.09), and higher stress (B = 0.18) were significantly associated with more RE, whereas taking medications to lose weight (B=-0.10) was significantly associated with less RE. The interaction body mass index (BMI) by body dissatisfaction was significantly associated with RE; in the group with low BMI, higher body dissatisfaction was significantly associated with more RE.

CONCLUSIONS

Our study showed that the Dutch Restrained Eating scale is an adapted and validated tool to be used among Lebanese adolescents and revealed factors associated with restrained eating in this population. Since restrained eating has been associated with many clinically-diagnosed eating disorders, the results of this study might serve as a first step towards the development of prevention strategies targeted towards promoting a healthy lifestyle in Lebanese adolescents.

High intensity interval training does not result in short- or long-term dietary compensation in cardiac rehabilitation: Results from the FITR heart study

The aim of this study was to investigate short- and long-term compensatory effects on dietary intake following high intensity interval training (HIIT) compared with usual care moderate intensity continuous training (MICT) during and following a cardiac rehabilitation program. This study investigates secondary outcomes of a clinical trial. Ninety-three participants with coronary artery disease enrolled in a 4-week cardiac rehabilitation program, were randomised to 1) 4x4-minute HIIT; or 2) 40-min of MICT (usual care). Patients were instructed to complete 3 weekly sessions (2 supervised, 1 home-based) for 4-weeks, and 3 weekly home-based sessions thereafter for another 48-weeks. Dietary intake was measured by telephone-based 24-h recall over 2 day at baseline, 4-weeks, 3-months, 6-months, and 12-months. Three-Factor Eating Questionnaire was used to measure dietary behaviour and Leeds Food Preference Questionnaire used to measure food preferences. Appetite was assessed by a visual analogue scale and appetite-regulating hormones. There was no change over the study period or differences between groups for daily energy intake at 4-weeks or 12-months. There were also no group differences for any other measures of dietary intake, fasting hunger or appetite-related hormones, dietary behaviour, or food preferences. These findings suggest that compared to moderate intensity exercise, HIIT does not result in compensatory increases of energy intake or indicators of poor diet quality. This finding appears to be the same for patients with normal weight and obesity. HIIT can therefore be included in cardiac rehabilitation programs as an adjunct or alterative to MICT, without concern for any undesirable dietary compensation.

Homeostatic and neurocognitive control of energy intake in response to exercise in pediatric obesity: a psychobiological framework

While energy intake and energy expenditure have long been studied independently, the alarming progression of obesity has led to a more integrative approach to energy balance considering their potential interactions. Although the available literature concerned with the effect of chronic and acute exercise on energy intake and appetite control in adults is considerable, these questions remain less explored among children and adolescents. Based on the search of four databases (Medline, Embase, PsycINFO and Cochrane Library; articles published until May 2018), the objective of this review is to summarize and discuss the effect of acute and chronic physical exercise on energy intake and appetite control in children and adolescents with obesity, and to identify the physiological and neurocognitive signals and pathways involved. Evidence suggested that acute intensive exercise has the potential to reduce subsequent energy intake in children and adolescents with obesity but not healthy weight, through both peripheral (mainly gastro-peptides) and neurocognitive (neural responses to food cues) pathways. The nutritional responses to chronic physical activity remain less clear and require further consideration, especially from an anti-obesity perspective.

Factors associated with restrained eating and validation of the Arabic version of the restrained eating scale among an adult representative sample of the Lebanese population: a cross-sectional study

BACKGROUND

Previous research suggests that restrained eating is problematic in Lebanon and is associated with the occurrence of clinically diagnosed eating disorders. Because of the alarming prevalence and severity of these disorders, the aim of this study is to investigate factors that may contribute to restrained eating in adults among a representative sample of the Lebanese population.

METHODS

This is a cross-sectional study conducted between January and May 2018; 811 adult participants were enrolled from all Lebanese districts. The Dutch Restrained Eating scale was used to measure body disturbance. The factors that were assessed in the questionnaire were body dissatisfaction, self-esteem, perceived stress, anxiety, depression, emotion regulation, emotional eating and adult attachment styles.

RESULTS

The mean age of the participants was 27.59 ± 11.76 years, and included 66.5% females. In the absence of a cutoff value for the Dutch Restrained Eating scale, we took the median (2.6) as the cutoff value. The results showed that 391 (48.3%) had restrained eating. The Dutch Restrained Eating scale items converged over a solution of one factor that had an Eigenvalue over 1, explaining a total of 60.69% of the variance (Cronbach's alpha was high =0.928). The linear regression results, taking the Dutch restrained eating scale as the dependent variable, showed that being a female (Beta = 0.31), increased age (Beta = 0.01), higher body mass index (Beta = 0.01), an intermediate monthly income (Beta = 0.25), higher body dissatisfaction scores (Beta = 0.03), higher adult anxiety attachment style (Beta = 0.008), higher emotion regulation cognitive reappraisal facet (Beta = 0.01), feeling pressure from TV/magazine to lose weight (Beta = 0.45) and practicing sport activities (Beta = 0.41) were associated with higher restrained eating scores.

CONCLUSION

Our findings show that numerous factors are associated with restrained eating in the Lebanese community. They include body dissatisfaction, cognitive reappraisal, female gender, eating attitudes, social media pressure and adult attachment. Therefore, the development of prevention strategies directed at an improved body image perception and increasing knowledge about factors that might influence this body image and critical thinking regarding media images is warranted, with the ultimate goal of promoting healthier choices in the Lebanese population.

The Unexplored Crossroads of the Female Athlete Triad and Iron Deficiency: A Narrative Review

Despite the severity and prevalence of iron deficiency in exercising women, few published reports have explored how iron deficiency interacts with another prevalent and severe condition in exercising women: the 'female athlete triad.' This review aims to describe how iron deficiency may interact with each component of the female athlete triad, that is, energy status, reproductive function, and bone health. The effects of iron deficiency on energy status are discussed in regards to thyroid function, metabolic fuel availability, eating behaviors, and energy expenditure. The interactions between iron deficiency and reproductive function are explored by discussing the potentially impaired fertility and hyperprolactinemia due to iron deficiency and the alterations in iron metabolism due to menstrual blood loss and estrogen exposure. The interaction of iron deficiency with bone health may occur via dysregulation of the growth hormone/insulin-like growth factor-1 axis, hypoxia, and hypothyroidism. Based on these discussions, several future directions for research are presented.

The effects of resveratrol intake on weight loss: a systematic review and meta-analysis of randomized controlled trials

This systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted to summarize the effect of resveratrol intake on weight loss. We searched the following databases until July 2018: MEDLINE, EMBASE, Web of Science and Cochrane Central Register of Controlled Trials. Data were pooled using the inverse variance method and expressed as standardized mean difference (SMD) with 95% confidence intervals (95% CI). Out of 831 reports, 36 RCTs were eligible for including to our meta-analysis. The pooled results, using random-effects model showed that resveratrol supplementation significantly decreased body weight (SMD = -0.17; 95% CI, -0.33, -0.01; P = 0.03; I²: 62.6), body mass index (BMI) (SMD = -0.20; 95% CI, -0.35, -0.05; P = 0.01; I²: 60.6), fat mass (SMD = -0.32; 95% CI, -0.62, -0.03; P = 0.03; I²: 77.9) and waist circumference (WC) (SMD = -0.42; 95% CI, -0.68, -0.16; P = 0.001; I²: 75.2), and significantly increased lean mass (SMD = 1.21; 95% CI, 0.75, 1.67; P < 0.001; I²: 87.6). We found no significant effect of resveratrol administration on leptin (SMD = -0.20; 95% CI, -0.68, 0.27; P = 0.40; I²: 85.3) and adiponectin levels (SMD = 0.08; 95% CI, -0.39, 0.55; P = 0.74; I²: 91.0). Resveratrol supplementation significantly decreased body weight in obese patients (SMD -0.43; 95% CI, -0.60, -0.26) compared with other diseases (SMD 0.02; 95% CI, -0.29, 0.33), and type 2 diabetes mellitus (SMD -0.17; 95% CI, -0.37, 0.02). Overall, the current meta-analysis demonstrated that resveratrol intake significantly reduced weight, BMI, WC and fat mass, and significantly increased lean mass, but did not affect leptin and adiponectin levels.

Does Habitual Physical Activity Increase the Sensitivity of the Appetite Control System? A Systematic Review

Background

It has been proposed that habitual physical activity improves appetite control; however, the evidence has never been systematically reviewed.

Objective

To examine whether appetite control (e.g. subjective appetite, appetite-related peptides, food intake) differs according to levels of physical activity.

Data Sources

Medline, Embase and SPORTDiscus were searched for articles published between 1996 and 2015, using keywords pertaining to physical activity, appetite, food intake and appetite-related peptides.

Study Selection

Articles were included if they involved healthy non-smoking adults (aged 18–64 years) participating in cross-sectional studies examining appetite control in active and inactive individuals; or before and after exercise training in previously inactive individuals.

Study Appraisal and Synthesis

Of 77 full-text articles assessed, 28 studies (14 cross-sectional; 14 exercise training) met the inclusion criteria.

Results

Appetite sensations and absolute energy intake did not differ consistently across studies. Active individuals had a greater ability to compensate for high-energy preloads through reductions in energy intake, in comparison with inactive controls. When physical activity level was graded across cross-sectional studies (low, medium, high, very high), a significant curvilinear effect on energy intake (z-scores) was observed.

Limitations

Methodological issues existed concerning the small number of studies, lack of objective quantification of food intake, and various definitions used to define active and inactive individuals.

Conclusion

Habitually active individuals showed improved compensation for the energy density of foods, but no consistent differences in appetite or absolute energy intake, in comparison with inactive individuals. This review supports a J-shaped relationship between physical activity level and energy intake. Further studies are required to confirm these findings.

PROSPERO Registration Number

CRD42015019696

Electronic supplementary material

The online version of this article (doi:10.1007/s40279-016-0518-9) contains supplementary material, which is available to authorized users.

The effects of ginger intake on weight loss and metabolic profiles among overweight and obese subjects: A systematic review and meta-analysis of randomized controlled trials

This systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to summarize the effect of ginger intake on weight loss, glycemic control and lipid profiles among overweight and obese subjects. We searched the following databases through November 2017: MEDLINE, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials. The relevant data were extracted and assessed for quality of the studies according to the Cochrane risk of bias tool. Data were pooled using the inverse variance method and expressed as Standardized Mean Difference (SMD) with 95% Confidence Intervals (95% CI). Heterogeneity between studies was assessed by the Cochran Q statistic and I-squared tests (I2). Overall, 14 studies were included in the meta-analyses. Fourteen RCTs with 473 subjects were included in our meta-analysis. The results indicated that the supplementation with ginger significantly decreased body weight (BW) (SMD -0.66; 95% CI, -1.31, -0.01; P = 0.04), waist-to-hip ratio (WHR) (SMD -0.49; 95% CI, -0.82, -0.17; P = 0.003), hip ratio (HR) (SMD -0.42; 95% CI, -0.77, -0.08; P = 0.01), fasting glucose (SMD -0.68; 95% CI, -1.23, -0.05; P = 0.03) and insulin resistance index (HOMA-IR) (SMD -1.67; 95% CI, -2.86, -0.48; P = 0.006), and significantly increased HDL-cholesterol levels (SMD 0.40; 95% CI, 0.10, 0.70; P = 0.009). We found no detrimental effect of ginger on body mass index (BMI) (SMD -0.65; 95% CI, -1.36, 0.06; P = 0.074), insulin (SMD -0.54; 95% CI, -1.43, 0.35; P = 0.23), triglycerides (SMD -0.27; 95% CI, -0.71, 0.18; P = 0.24), total- (SMD -0.20; 95% CI, -0.58, 0.18; P = 0.30) and LDL-cholesterol (SMD -0.13; 95% CI, -0.51, 0.24; P = 0.48). Overall, the current meta-analysis demonstrated that ginger intake reduced BW, WHR, HR, fasting glucose and HOMA-IR, and increased HDL-cholesterol, but did not affect insulin, BMI, triglycerides, total- and LDL-cholesterol levels.

The Chronic Effect of Interval Training on Energy Intake: A Systematic Review and Meta-Analysis

Single bouts of acute exercise do not appear to increase subsequent energy intake (EI), even when energy deficit is large. However, studies have shown a compensatory effect on EI following chronic exercise, and it remains unclear whether this is affected by exercise intensity. We investigated the chronic effect of high-intensity interval training (HIIT) and sprint interval training (SIT) on EI when compared with moderate-intensity continuous training (MICT) or no exercise (CON). Databases were searched until 13 March 2017 for studies measuring EI in response to chronic exercise (≥4 weeks of duration) of a high-intensity interval nature. Meta-analysis was conducted for between-group comparisons on EI (kilojoules) and bodyweight (kg). Results showed large heterogeneity, and therefore, metaregression analyses were conducted. There were no significant differences in EI between HIIT/SIT versus MICT (P=0.282), HIIT/SIT versus CON (P=0.398), or MICT versus CON (P=0.329). Although bodyweight was significantly reduced after HIIT/SIT versus CON but not HIIT/SIT versus MICT (in studies measuring EI), this was not clinically meaningful (<2% mean difference). In conclusion, there is no compensatory increase in EI following a period of HIIT/SIT compared to MICT or no exercise. However, this review highlights important methodological considerations for future studies.

Acute effects of exercise intensity on subsequent substrate utilisation, appetite, and energy balance in men and women

Exercise is capable of influencing the regulation of energy balance by acutely modulating appetite and energy intake coupled to effects on substrate utilization. Yet, few studies have examined acute effects of exercise intensity on aspects of both energy intake and energy metabolism, independently of energy cost of exercise. Furthermore, little is known as to the gender differences of these effects. One hour after a standardised breakfast, 40 (19 female), healthy participants (BMI 23.6 ± 3.6 kg·m−2, V̇O2peak 34.4 ± 6.8 mL·kg−1·min−1) undertook either high-intensity intermittent cycling (HIIC) consisting of 8 repeated 60 s bouts of cycling at 95% V̇O2peak or low-intensity continuous cycling (LICC), equivalent to 50% V̇O2peak, matched for energy cost (∼950 kJ) followed by 90 mins of rest, in a randomised crossover design. Throughout each study visit, satiety was assessed subjectively using visual analogue scales alongside blood metabolites and GLP-1. Energy expenditure and substrate utilization were measured over 75 min postexercise via indirect calorimetry. Energy intake was assessed for 48 h postintervention. No differences in appetite, GLP-1, or energy intakes were observed between HIIC and LICC, with or without stratifying for gender. Significant differences in postexercise nonesterified fatty acid concentrations were observed between intensities in both genders, coupled to a significantly lower respiratory exchange ratio following HIIC (P = 0.0028), with a trend towards greater reductions in respiratory exchange ratioin males (P = 0.079). In conclusion, high-intensity exercise, if energy matched, does not lead to greater appetite or energy intake, but may exert additional beneficial metabolic effects that may be more pronounced in males.

Obesity and energy balance: What is the role of physical activity?

Despite billions of dollars spent over decades of research, debate remains over the causes and solutions of the obesity epidemic. The specific role of physical activity in the prevention or treatment of obesity seems a particularly contentious issue, with opposing views put forth in both academic and popular media. In an attempt to provide context and clarity to the specific question of the role of physical activity in determination of body weight, we have attempted to identify evidence or lack thereof in the scientific literature and provide a summary of our findings. Areas covered: Topics included in this narrative review are an overview of energy balance, the relationship between physical activity and energy expenditure, compensatory responses in non-exercise energy expenditure and energy intake, and the relationship between physical activity and obesity. Expert commentary: Based on a review of the existing literature, daily physical activity and structured exercise has beneficial effects on an individual's body weight. In most instances, exercise occurring in adequate amounts will increase total daily energy expenditure and create an acute energy deficit, without compensatory decreases in non-exercise physical activity or energy expenditure nor compensatory increases in energy intake. Several gaps in the literature exist, both in terms of the number of adequately powered clinical trials with rigorous assessments of both energy intake and expenditure, and with a variety of study populations (by age, sex, race, etc.) and with varying exercise volumes and intensities.

Energy compensation following consumption of sugar-reduced products: a randomized controlled trial

PURPOSE

Consumption of sugar-reformulated products (commercially available foods and beverages that have been reduced in sugar content through reformulation) is a potential strategy for lowering sugar intake at a population level. The impact of sugar-reformulated products on body weight, energy balance (EB) dynamics and cardiovascular disease risk indicators has yet to be established. The REFORMulated foods (REFORM) study examined the impact of an 8-week sugar-reformulated product exchange on body weight, EB dynamics, blood pressure, arterial stiffness, glycemia and lipemia.

METHODS

A randomized, controlled, double-blind, crossover dietary intervention study was performed with fifty healthy normal to overweight men and women (age 32.0 ± 9.8 year, BMI 23.5 ± 3.0 kg/m(2)) who were randomly assigned to consume either regular sugar or sugar-reduced foods and beverages for 8 weeks, separated by 4-week washout period. Body weight, energy intake (EI), energy expenditure and vascular markers were assessed at baseline and after both interventions.

RESULTS

We found that carbohydrate (P < 0.001), total sugars (P < 0.001) and non-milk extrinsic sugars (P < 0.001) (% EI) were lower, whereas fat (P = 0.001) and protein (P = 0.038) intakes (% EI) were higher on the sugar-reduced than the regular diet. No effects on body weight, blood pressure, arterial stiffness, fasting glycemia or lipemia were observed.

CONCLUSIONS

Consumption of sugar-reduced products, as part of a blinded dietary exchange for an 8-week period, resulted in a significant reduction in sugar intake. Body weight did not change significantly, which we propose was due to energy compensation.

Exercise and diabetes: relevance and causes for response variability

Exercise as a key prevention strategy for diabetes and obesity is commonly accepted and recommended throughout the world. Unfortunately, not all individuals profit to the same extent, some exhibit exercise resistance. This phenomenon of non-response to exercise is found for several endpoints, including glucose tolerance and insulin sensitivity. Since these non-responders are of notable quantity, there is the need to understand the underlying mechanisms and to identify predictors of response. This displays the basis to develop personalized training intervention regimes. In this review, we summarize the current knowledge on response variability, with focus on human studies and improvement of glucose homeostasis as outcome.

Breaking up prolonged sitting time with walking does not affect appetite or gut hormone concentrations but does induce an energy deficit and suppresses postprandial glycaemia in sedentary adults

Breaking up periods of prolonged sitting can negate harmful metabolic effects but the influence on appetite and gut hormones is not understood and is investigated in this study. Thirteen sedentary (7 female) participants undertook three 5-h trials in random order: (i) uninterrupted sitting (SIT), (ii) seated with 2-min bouts of light-intensity walking every 20 min (SIT + LA), and (iii) seated with 2-min bouts of moderate-intensity walking every 20 min (SIT + MA). A standardised test drink was provided at the start of each trial and an ad libitum pasta test meal provided at the end of each trial. Subjective appetite ratings and plasma acylated ghrelin, peptide YY, insulin, and glucose were measured at regular intervals. Area under the curve (AUC) was calculated for each variable. AUC values for appetite and gut hormone concentrations were unaffected in the activity breaks conditions compared with uninterrupted sitting (linear mixed modelling: p > 0.05). Glucose AUC was lower in SIT + MA than in SIT + LA (p = 0.004) and SIT (p = 0.055). There was no difference in absolute ad libitum energy intake between conditions (p > 0.05); however, relative energy intake was lower in SIT + LA (39%; p = 0.011) and SIT + MA (120%; p < 0.001) than in SIT. In conclusion, breaking up prolonged sitting does not alter appetite and gut hormone responses to a meal over a 5-h period. Increased energy expenditure from activity breaks could promote an energy deficit that is not compensated for in a subsequent meal.

Exercise-trained men and women: role of exercise and diet on appetite and energy intake

The regulation of appetite and energy intake is influenced by numerous hormonal and neural signals, including feedback from changes in diet and exercise. Exercise can suppress subjective appetite ratings, subsequent energy intake, and alter appetite-regulating hormones, including ghrelin, peptide YY, and glucagon-like peptide 1(GLP-1) for a period of time post-exercise. Discrepancies in the degree of appetite suppression with exercise may be dependent on subject characteristics (e.g., body fatness, fitness level, age or sex) and exercise duration, intensity, type and mode. Following an acute bout of exercise, exercise-trained males experience appetite suppression, while data in exercise-trained women are limited and equivocal. Diet can also impact appetite, with low-energy dense diets eliciting a greater sense of fullness at a lower energy intake. To date, little research has examined the combined interaction of exercise and diet on appetite and energy intake. This review focuses on exercise-trained men and women and examines the impact of exercise on hormonal regulation of appetite, post-exercise energy intake, and subjective and objective measurements of appetite. The impact that low-energy dense diets have on appetite and energy intake are also addressed. Finally, the combined effects of high-intensity exercise and low-energy dense diets are examined. This research is in exercise-trained women who are often concerned with weight and body image issues and consume low-energy dense foods to keep energy intakes low. Unfortunately, these low-energy intakes can have negative health consequences when combined with high-levels of exercise. More research is needed examining the combined effect of diet and exercise on appetite regulation in fit, exercise-trained individuals.

Beyond weight reduction: improvements in quality of life after an intensive lifestyle intervention in subjects with severe obesity

INTRODUCTION

We examined the effects of 10-14 weeks of inpatient intensive lifestyle intervention (ILI), including a minimum of 90 minutes of adapted physical activity 5 days/week, with regard to changes in quality of life and associations with weight loss in subjects with severe obesity.

METHODS

A total of 100 severely obese subjects (BMI 42.6 ± 5.3 kg/m(2); 42.7 ± 10.6 years) were included. Quality of life was assessed by Binge Eating Scale, Hospital Anxiety, and Depression Scale, and SF- 36. The ILI group completed the questionnaires at inclusion, after 10-14 weeks and 12 months, and controls at inclusion and after 10-14 weeks.

RESULTS

Compared to controls, self-reported binge eating (-6.4, P < 0.0001), anxiety (-1.7, P = 0.005), and depression (-3.0, P < 0.0001) were reduced, and physical (8.0, P < 0.0001) and mental (7.6, P < 0.0001) health increased in the ILI group. After 12 months, reduction in self-reported binge eating (-7.2, P < 0.0001) and depression (-3.4, P < 0.0001) and increase in physical (8.9, P < 0.0001) and mental (3.6, P = 0.035) health were maintained. Decreased self-reported binge eating (β = 0.555, P = 0.010) and increased physical health (β = -0.554, P = 0.003) were associated with weight loss.

CONCLUSION

ILI including a high volume of physical activity in subjects with severe obesity improved quality of life by favorable changes in self-reported binge eating, depression, and mental and physical health. Improvements in binge eating and physical health were associated with weight loss.

Myokines in insulin resistance and type 2 diabetes

Skeletal muscle represents the largest organ of the body in non-obese individuals and is now considered to be an active endocrine organ releasing a host of so-called myokines. These myokines are part of a complex network that mediates communication between muscle, the liver, adipose tissue, the brain and other organs. Recent data suggest that myokines regulated by muscle contraction may play a key role in mediating the health-promoting effects of regular physical activity. Although hundreds of myokines have recently been described in proteomic studies, we currently have a rather limited knowledge of the specific role these myokines play in the prevention of insulin resistance, inflammation and associated metabolic dysfunction. Several myokines are known to have both local and endocrine functions, but in many cases the contribution of physical activity to the systemic level of these molecules remains as yet unexplored. Very recently, novel myokines such as irisin, which is thought to induce a white to brown shift in adipocytes, have gained considerable interest as potential therapeutic targets. In this review, we summarise the most recent findings on the role of myokines in the regulation of substrate metabolism and insulin sensitivity. We further explore the role of myokines in the regulation of inflammation and provide a critical assessment of irisin and other myokines regarding their potential as therapeutic targets.

Does increased exercise or physical activity alter ad-libitum daily energy intake or macronutrient composition in healthy adults? A systematic review

BACKGROUND

The magnitude of the negative energy balance induced by exercise may be reduced due to compensatory increases in energy intake.

OBJECTIVE

TO ADDRESS THE QUESTION: Does increased exercise or physical activity alter ad-libitum daily energy intake or macronutrient composition in healthy adults?

DATA SOURCES

PubMed and Embase were searched (January 1990-January 2013) for studies that presented data on energy and/or macronutrient intake by level of exercise, physical activity or change in response to exercise. Ninety-nine articles (103 studies) were included.

STUDY ELIGIBILITY CRITERIA

Primary source articles published in English in peer-reviewed journals. Articles that presented data on energy and/or macronutrient intake by level of exercise or physical activity or changes in energy or macronutrient intake in response to acute exercise or exercise training in healthy (non-athlete) adults (mean age 18-64 years).

STUDY APPRAISAL AND SYNTHESIS METHODS

Articles were grouped by study design: cross-sectional, acute/short term, non-randomized, and randomized trials. Considerable heterogeneity existed within study groups for several important study parameters, therefore a meta-analysis was considered inappropriate. Results were synthesized and presented by study design.

RESULTS

No effect of physical activity, exercise or exercise training on energy intake was shown in 59% of cross-sectional studies (n = 17), 69% of acute (n = 40), 50% of short-term (n = 10), 92% of non-randomized (n = 12) and 75% of randomized trials (n = 24). Ninety-four percent of acute, 57% of short-term, 100% of non-randomized and 74% of randomized trials found no effect of exercise on macronutrient intake. Forty-six percent of cross-sectional trials found lower fat intake with increased physical activity.

LIMITATIONS

The literature is limited by the lack of adequately powered trials of sufficient duration, which have prescribed and measured exercise energy expenditure, or employed adequate assessment methods for energy and macronutrient intake.

CONCLUSIONS

We found no consistent evidence that increased physical activity or exercise effects energy or macronutrient intake.

Weight gain as a consequence of living a modern lifestyle: a discussion of barriers to effective weight control and how to overcome them

OBJECTIVE

The purpose of this commentary is to discuss modern lifestyle factors that promote weight gain and to suggest methods for clinicians to more effectively educate patients about weight management.

DISCUSSION

Most adults in the United States are overweight or obese. Multiple factors related to the modern lifestyle appear to play causal roles. In general, the population maintains sedentary lives and overconsumes calorie-dense foods. In particular, refined carbohydrates negatively impact metabolism and stimulate neural addiction mechanisms, which facilitate weight gain. As adipose tissue mass accumulates, satiation centers in the hypothalamus become resistant to insulin and leptin, which leads to increased caloric consumption. Several behavior issues further augment weight gain, such as eating too quickly, a lack of sleep, high stress levels, and a lack of exercise. Finally, adipose tissue accumulation alters the body weight set point, which leads to metabolic changes that function to resist weight loss efforts. Each of these factors may work together to augment weight gain and promote obesity. Health care providers, such as chiropractic physicians, who educate patients on wellness, prevention, and lifestyle changes are well positioned to address these issues.

CONCLUSION

People need to be educated about the modern lifestyle factors that prevent effective weight management. Without this knowledge and the associated practical application of lifestyle choices that prevent weight gain, becoming overweight or obese appears to be an unavoidable consequence of living a modern lifestyle.

Satiety, but not total PYY, Is increased with continuous and intermittent exercise

OBJECTIVE

This study determined the hormonal and subjective appetite responses to exercise (1-h continuous versus intermittent exercise throughout the day) in obese individuals.

DESIGN AND METHODS

Eleven obese subjects (>30 kg/m(2) ) underwent three 12-h study days: control condition [sedentary behavior (SED)], continuous exercise condition [(EX) 1-h exercise], and intermittent exercise condition [(INT) 12 hourly, 5-min bouts]. Blood samples (every 10 min) were measured for serum insulin and total peptide YY (PYY) concentrations, with ratings of appetite (visual analog scale [VAS): every 20 min]. Both total area under the curve (AUC), and subjective appetite ratings were calculated.

RESULTS

No differences were observed in total PYY AUC between conditions, but hunger was reduced with INT (INT < EX; P < 0.05), and satiety was increased with both SED and INT conditions (INT > EX and SED > EX; P < 0.05). A correlation existed between the change in total PYY and insulin levels (r = -0.81; P < 0.05), and total PYY and satiety (r = 0.80; P < 0.05) with the EX condition, not the SED and INT conditions.

CONCLUSIONS

The total PYY response to meals is not altered over the course of a 12-h day with either intermittent or continuous exercise; however, intermittent exercise increased satiety and reduced hunger to a greater extent than continuous exercise in obese individuals.

Identifying molecular targets of lifestyle modifications in colon cancer prevention

One in four deaths in the United States is cancer-related, and colorectal cancer (CRC) is the second leading cause of cancer-associated deaths. Screening strategies are utilized but have not reduced disease incidence or mortality. In this regard, there is an interest in cancer preventive strategies focusing on lifestyle intervention, where specific etiologic factors involved in cancer initiation, promotion, and progression could be targeted. For example, exposure to dietary carcinogens, such as nitrosamines and polycyclic aromatic hydrocarbons influences colon carcinogenesis. Furthermore, dietary deficiencies could alter sensitivity to genetic damage and influence carcinogen metabolism contributing to CRC. High alcohol consumption increases the risk of mutations including the fact that acetaldehyde, an ethanol metabolite, is classified as a group 1 carcinogen. Tobacco smoke exposure is also a risk factor for cancer development; approximately 20% of CRCs are associated with smoking. Additionally, obese patients have a higher risk of cancer development, which is further supported by the fact that physical activity decreases CRC risk by 55%. Similarly, chronic inflammatory conditions also increase the risk of CRC development. Moreover, the circadian clock alters digestion and regulates other biochemical, physiological, and behavioral processes that could influence CRC. Taken together, colon carcinogenesis involves a number of etiological factors, and therefore, to create effective preventive strategies, molecular targets need to be identified and beleaguered prior to disease progression. With this in mind, the following is a comprehensive review identifying downstream target proteins of the above lifestyle risk factors, which are modulated during colon carcinogenesis and could be targeted for CRC prevention by novel agents including phytochemicals.

Activity related energy expenditure, appetite and energy intake: potential implications for weight management

The aim was to investigate relationships between activity related energy expenditure (AREE), appetite ratings and energy intake (EI) in a sample of 40 male (26.4years; BMI 23.5kg/m(2)) and 42 female (26.9years; BMI 22.4kg/m(2)) participants. AREE was expressed as the residual value of the regression between total daily EE (by doubly labeled water) and resting EE (by indirect calorimetry). EI was measured using an ad libitum buffet meal and visual analogue scales measured subjective appetite ratings before and after the meal. AREE was divided into low, middle and high sex-specific tertiles. General linear models were used to investigate differences in appetite ratings and EI across AREE tertiles. Before the meal, males in the high AREE tertile had significantly lower desire to eat and lower prospective food consumption and higher feelings of fullness compared to those in the low tertile. Males in the middle tertile had significantly higher satiety quotients after the meal and lower EI compared to the other tertiles. No significant differences across tertiles were found in females. Sex differences in relationships between AREE, appetite ratings and EI may lead to differing patterns of EI and subsequent weight maintenance.

Biomarker Profile Does Not Predict Weight Loss Success in Successful and Unsuccessful Diet-Reduced Obese Individuals: a Prospective Study

Background. Individuals attempting weight reduction have varying success when participating in the same intervention. Identifying physiological factors associated with greater weight loss could improve outcomes. Methods. Sixty-one adults (BMI 27–30 kg/m²) participated in a 16-week group-based, cognitive-behavioral control weight loss program. Concentrations of 12 fasting hormones and cytokines related to adiposity, satiety/hunger, and inflammation were measured using the Milliplex human metabolic human panel before and after weight loss. Participants were grouped based on ≥8% (successful group, SG) or <8% weight loss (less successful group, LSG). Results. The SG had 46 subjects (75.4%), while the LSG had 15 (24.6%). There were no differences in baseline sex distribution, age, weight, BMI, and body composition between groups. In the SG, baseline to the 16-week levels decreased significantly for c-peptide (1,030 versus 891 pg/mL, P = 0.002), insulin (665 versus 541 pg/mL, P = 0.001), and leptin (0.83 versus 0.58 ng/mL/kg fat, P < 0.001). None of the baseline analytes predicted greater weight loss. Conclusions. Successful weight loss was associated with changes in adiposity (less fat mass) and unfavorable hunger signals. No baseline biomarker profile was associated with weight loss success. Behavioral factors may have outweighed physiological signals for determining successful weight loss. This trial is registered with Clinicaltrials.gov NCT00429650.

Walking attenuates the relationships of high-meat, low-fruit dietary intake to total and regional adiposity in men and women

Vigorous physical activity (running) has been shown to attenuate the association between diet and body weight. Walking is the most popular physical activity, but is a moderate-intensity physical activity because it requires less than sixfold the energy expenditure of sitting at rest. We therefore examined whether reported distance walked per week affected the relationship of diet to BMI and circumferences of the waist, hip, and chest in 30,014 female and 7,133 male participants of the National Walkers' Health Study. Reported meat and fruit intakes served as indicators of high-risk diets for weight gain. The analyses showed that higher meat and lower fruit intake were significantly and consistently associated with greater BMI and waist circumference at all activity levels. Longer usual walking distance significantly attenuated the concordant relationships of diet with women's BMIs (P < 10(-8)), men's BMIs (P = 0.04), and women's waist (P < 10(-6)), hip (P = 0.0001), and chest circumferences (P < 10(-5)). Compared to walkers who averaged <1.5 km/day, the association of diet with adiposity in subjects who walked ≥1.5 km/day was reduced 21% in women and 31% in men for BMI; 20% in women and 27% in men for waist circumference; 19% for women's hip circumference; and 26% for women's chest circumference. Thus we conclude that diets characterized by high-meat/low-fruit intake were significantly associated with greater BMI, and this association was attenuated by moderate physical activity. The weaker results in men than women probably related to the smaller sample size, and reduced statistical power of the men.

Attenuating effect of vigorous physical activity on the risk for inherited obesity: a study of 47,691 runners

Objective

Physical activity has been shown to attenuate the effect of the FTO polymorphism on body weight, and the heritability of body weight in twin and in family studies. The dose-response relationship between activity and the risk for inherited obesity is not well known, particularly for higher doses of vigorous exercise. Such information is needed to best prescribe an exercise dose for obesity prevention in those at risk due to their family history.

Design

We therefore analyzed self-reported usual running distance, body mass index (BMI), waist circumference, and mother's and father's adiposity (1 = lean, 2 = normal, 3 = overweight, and 4 = very overweight) from survey data collected on 33,480 male and 14,211 female runners. Age-, education-, and alcohol-adjusted regression analyses were used to estimate the contribution of parental adiposities to the BMI and waist circumferences in runners who ran an average of <3, 3–6, 6–9, ≥9 km/day.

Results

BMI and waist circumferences of runners who ran <3 km/day were significantly related to their parents adiposity (P<10⁻¹⁵ and P<10⁻¹¹, respectively). These relationships (i.e., kg/m² or cm per increment in parental adiposity) diminished significantly with increasing running distance for both BMI (inheritance×exercise interaction, males: P<10⁻¹⁰; females: P<10⁻⁵) and waist circumference (inheritance×exercise interaction, males: P<10⁻⁹; females: P = 0.004). Compared to <3 km/day, the parental contribution to runners who averaged ≥9 km/day was diminished by 48% for male BMI, 58% for female BMI, 55% for male waist circumference, and 58% for female waist circumference. These results could not be attributed to self-selection.

Conclusions

Exceeding the minimum exercise dose currently recommended for general health benefits (energy equivalent to running 2–3 km/day) may substantially diminish the risk for inherited obesity. The results are consistent with other research suggesting the physical activity dose required to prevent unhealthy weight gain is greater than that recommended for other health benefits.

Exercise attenuates the association of body weight with diet in 106,737 runners

PURPOSE

The high prevalence of obesity in Western societies has been attributed in part to high-fat low-CHO food consumption. However, people have also become less active, and inactivity may have increased the risk for weight gain from poor dietary choices. Analyses were performed to test whether diet-weight relationships were attenuated by vigorous exercise.

METHODS

Age- and education-adjusted cross-sectional regression analyses of 62,042 men and 44,695 women recruited for the National Runners' Health Study were conducted. Reported meat and fruit intakes were analyzed separately and as indicators of high-risk diets.

RESULTS

The runners were generally lean (mean ± SD: males = 24.15 ± 2.81 kg·m(-2), females = 21.63 ± 2.70 kg·m(-2)) as measured by body mass index (BMI), educated (males = 16.42 ± 2.47 yr, females = 16.04 ± 2.32 yr), and middle-aged (males = 44.40 ± 10.83 yr, females = 38.21 ± 10.08 yr), who ran 5.30 ± 3.23 km·d(-1) if male and 4.79 ± 3.00 km·d(-1) if female. Running significantly attenuated BMI's relationship to reported meat and fruit intakes in men (P < 10(-8) and P < 10(-12), respectively) and women (P < 10(-15) and P < 10(-6), respectively). Specifically, compared with running <2 km·d(-1), running >8 km·d(-1) reduced the apparent BMI increase per serving of meat by 43% in men (slope ± SE = from 0.74 ± 0.10 to 0.42 ± 0.06) and 55% in women (from 1.26 ± 0.13 to 0.57 ± 0.09) and reduced the apparent BMI reduction per serving of fruit by 75% in men (from -0.28 ± 0.04 to -0.07 ± 0.02) and 94% in women (from -0.16 ± 0.05 to -0.01 ± 0.02). Running also significantly attenuated the concordant relationship between reported meat intake and waist and chest circumferences in men (P < 10(-9) and P = 0.0002, respectively) and women (P = 0.0004 and P < 10(-5), respectively) and the concordant relationship between meat intake and hip circumference in women (P < 10(-6)).

CONCLUSIONS

Vigorous exercise may mitigate diet-induced weight gain, albeit not guaranteeing protection from poor dietary choices.

Dose-response relationship between walking and the attenuation of inherited weight

OBJECTIVE

Genetic factors account for 40%-70% of the variation in body mass index (BMI). We sought to test whether moderate intensity physical activity affected parent-offspring relationships for body mass index and regional adiposity in 26,587 female and 6428 male walkers surveyed in the United States in 2000.

METHODS

Survey questionnaires provided self-reported usual walking distance, height, weight, and waist circumference, and mother's and father's adiposity (1=lean, 2=normal, 3=overweight, and 4=very overweight). Regression analyses were used to test whether the contribution of parental adiposities to the walkers' body mass indexes and waist circumferences diminished with walking.

RESULTS

In the most sedentary group (walking < 1.5 km/d), average parental adiposity was a significant determinant of the walkers' body mass indexes and waist circumferences (female: P < 10(-15); male: P < 10(-13)). Greater walking distance significantly diminished the effect of average parents' adiposity on the walkers' body mass indexes (female: P < 10(-10); male P = 0.003) and waist circumferences (female: P < 10(-6); male P = 0.01). Compared to the most sedentary female walkers, the effect of parental adiposity was reduced 36% for body mass indexes and 41% for waist circumferences (corresponding reductions in men were 36% and 46%, respectively).

CONCLUSION

These results suggest that moderate intensity physical activity attenuates inheritance of both total and regional adiposity in a dose-dependent manner.

IL-6 and IL-10 anti-inflammatory activity links exercise to hypothalamic insulin and leptin sensitivity through IKKbeta and ER stress inhibition

Overnutrition caused by overeating is associated with insulin and leptin resistance through IKKbeta activation and endoplasmic reticulum (ER) stress in the hypothalamus. Here we show that physical exercise suppresses hyperphagia and associated hypothalamic IKKbeta/NF-kappaB activation by a mechanism dependent upon the pro-inflammatory cytokine interleukin (IL)-6. The disruption of hypothalamic-specific IL-6 action blocked the beneficial effects of exercise on the re-balance of food intake and insulin and leptin resistance. This molecular mechanism, mediated by physical activity, involves the anti-inflammatory protein IL-10, a core inhibitor of IKKbeta/NF-kappaB signaling and ER stress. We report that exercise and recombinant IL-6 requires IL-10 expression to suppress hyperphagia-related obesity. Moreover, in contrast to control mice, exercise failed to reverse the pharmacological activation of IKKbeta and ER stress in C3H/HeJ mice deficient in hypothalamic IL-6 and IL-10 signaling. Hence, inflammatory signaling in the hypothalamus links beneficial physiological effects of exercise to the central action of insulin and leptin.

The impact of physical exercise on the gastrointestinal tract

PURPOSE OF REVIEW

Physical exercise can be both beneficial and harmful for the gastrointestinal tract in a dose-effect relationship between its intensity and health. Mild-to-moderate intensity exercises play a protective role against colon cancer, diverticular disease, cholelithiasis and constipation, whereas acute strenuous exercise may provoke heartburn, nausea, vomiting, abdominal pain, diarrhea and even gastrointestinal bleeding. This review focuses on mechanisms involved in those symptoms and their associations with type of exercises in humans.

RECENT FINDINGS

One quarter to one half of elite athletes are hampered by the gastrointestinal symptoms that may deter them from participation in training and competitive events. Vigorous exercise-induced gastrointestinal symptoms are often attributed to altered motility, mechanical factor or altered neuroimmunoendocrine secretions. Training, lifestyle modifications, meal composition, adequate hydration and avoidance of excessive use of some medications are the recommendations.

SUMMARY

Strenuous exercise and dehydrated states would be the causes of gastrointestinal symptoms referred by 70% of the athletes. Gut ischemia would be the main cause of nausea, vomiting, abdominal pain and (bloody) diarrhea. The frequency is almost twice as high during running than during other endurance sports as cycling or swimming and 1.5-3.0 times higher in the elite athletes than the recreational exercisers.

Ideal weight and weight satisfaction: association with health practices

Evidence suggests that individuals have become more tolerant of higher body weights over time. To investigate this issue further, the authors examined cross-sectional associations among ideal weight, examination year, and obesity as well as the association of ideal weight and body weight satisfaction with health practices among 15,221 men and 4,126 women in the United States. Participants in 1987 reported higher ideal weights than participants in 2001, an effect particularly pronounced from 1987 to 2001 for younger and obese men (85.5 kg to 94.9 kg) and women (62.2 kg to 70.5 kg). For a given body mass index, higher ideal body weights were associated with greater weight satisfaction but lower intentions to lose weight. Body weight satisfaction was subsequently associated with greater walking/jogging, better diet, and lower lifetime weight loss but with less intention to change physical activity and diet or lose weight (P < 0.01). Conversely, body mass index was negatively associated with weight satisfaction (P < 0.01) and was associated with less walking/jogging, poorer diet, and greater lifetime weight loss but with greater intention to change physical activity and diet or lose weight. Although the health implications of these findings are somewhat unclear, increased weight satisfaction, in conjunction with increases in societal overweight/obesity, may result in decreased motivation to lose weight and/or adopt healthier lifestyle behaviors.

Central exercise action increases the AMPK and mTOR response to leptin

AMP-activated protein kinase (AMPK) and mammalian Target of Rapamycin (mTOR) are key regulators of cellular energy balance and of the effects of leptin on food intake. Acute exercise is associated with increased sensitivity to the effects of leptin on food intake in an IL-6-dependent manner. To determine whether exercise ameliorates the AMPK and mTOR response to leptin in the hypothalamus in an IL-6-dependent manner, rats performed two 3-h exercise bouts, separated by one 45-min rest period. Intracerebroventricular IL-6 infusion reduced food intake and pretreatment with AMPK activators and mTOR inhibitor prevented IL-6-induced anorexia. Activators of AMPK and fasting increased food intake in control rats to a greater extent than that observed in exercised ones, whereas inhibitor of AMPK had the opposite effect. Furthermore, the reduction of AMPK and ACC phosphorylation and increase in phosphorylation of proteins involved in mTOR signal transduction, observed in the hypothalamus after leptin infusion, were more pronounced in both lean and diet-induced obesity rats after acute exercise. Treatment with leptin reduced food intake in exercised rats that were pretreated with vehicle, although no increase in responsiveness to leptin-induced anorexia after pretreatment with anti-IL6 antibody, AICAR or Rapamycin was detected. Thus, the effects of leptin on the AMPK/mTOR pathway, potentiated by acute exercise, may contribute to appetite suppressive actions in the hypothalamus.

Influence of resistance and aerobic exercise on hunger, circulating levels of acylated ghrelin, and peptide YY in healthy males

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 randomized 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.