Moderate physical activity permits acute coupling between serum leptin and appetite–satiety measures in obese women

Circadian Rhythms, Chrononutrition, Physical Training, and Redox Homeostasis-Molecular Mechanisms in Human Health

A multitude of physiological processes, human behavioral patterns, and social interactions are intricately governed by the complex interplay between external circumstances and endogenous circadian rhythms. This multidimensional regulatory framework is susceptible to disruptions, and in contemporary society, there is a prevalent occurrence of misalignments between the circadian system and environmental cues, a phenomenon frequently associated with adverse health consequences. The onset of most prevalent current chronic diseases is intimately connected with alterations in human lifestyle practices under various facets, including the following: reduced physical activity, the exposure to artificial light, also acknowledged as light pollution, sedentary behavior coupled with consuming energy-dense nutriments, irregular eating frameworks, disruptions in sleep patterns (inadequate quality and duration), engagement in shift work, and the phenomenon known as social jetlag. The rapid evolution of contemporary life and domestic routines has significantly outpaced the rate of genetic adaptation. Consequently, the underlying circadian rhythms are exposed to multiple shifts, thereby elevating the susceptibility to disease predisposition. This comprehensive review endeavors to synthesize existing empirical evidence that substantiates the conceptual integration of the circadian clock, biochemical molecular homeostasis, oxidative stress, and the stimuli imparted by physical exercise, sleep, and nutrition.

Exercise and Weight Management: The Role of Leptin-A Systematic Review and Update of Clinical Data from 2000-2022

A well-balanced metabolism means a lower risk for metabolism-related neuropsychiatric disorders. Leptin is a secretory adipokine involved in the central control of appetite that appears to play a role in the etiology of feeding-related disorders. Additionally, the influence of exercise on feeding behaviors potentially modulates the circulation of metabolites that signal through the central nervous system. In this systematic review, we collected the recent clinical evidence on the effect of exercise on leptin concentrations in health individuals published from 2000 to 20 September 2022, according to the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA 2020 statement). Six hundred and thirty-eight papers were retrieved and forty-eight papers were included in the qualitative synthesis. Data supports that exercise positively influences appetite via enhancing peripheral and central leptin signaling (reuptake), especially during weight loss. Exercise modulation of leptin signaling through leptin receptors helps to stabilize increases in food intake during periods of negative energy balance, prior to a decrease in the body fat tissue content. At a high intensity, exercise appears to counteract leptin resistance.

Insights into the constellating drivers of satiety impacting dietary patterns and lifestyle

Food intake and body weight regulation are of special interest for meeting today's lifestyle essential requirements. Since balanced energy intake and expenditure are crucial for healthy living, high levels of energy intake are associated with obesity. Hence, regulation of energy intake occurs through short- and long-term signals as complex central and peripheral physiological signals control food intake. This work aims to explore and compile the main factors influencing satiating efficiency of foods by updating recent knowledge to point out new perspectives on the potential drivers of satiety interfering with food intake regulation. Human internal factors such as genetics, gender, age, nutritional status, gastrointestinal satiety signals, gut enzymes, gastric emptying rate, gut microbiota, individual behavioral response to foods, sleep and circadian rhythms are likely to be important in determining satiety. Besides, the external factors (environmental and behavioral) impacting satiety efficiency are highlighted. Based on mechanisms related to food consumption and dietary patterns several physical, physiological, and psychological factors affect satiety or satiation. A complex network of endocrine and neuroendocrine mechanisms controls the satiety pathways. In response to food intake and other behavioral cues, gut signals enable endocrine systems to target the brain. Intestinal and gastric signals interact with neural pathways in the central nervous system to halt eating or induce satiety. Moreover, complex food composition and structures result in considerable variation in satiety responses for different food groups. A better understanding of foods and factors impacting the efficiency of satiety could be helpful in making smart food choices and dietary recommendations for a healthy lifestyle based on updated scientific evidence.

Examining the obesity paradox: A moderating effect of fitness on adipose endocrine function in older adults

Despite evidence linking obesity with increased mortality, older adults with excessive adiposity seem protected, resulting in a so-called obesity paradox. Obesity is characterized by leptin resistance, which contributes to increased risk of all-cause mortality. Therefore, lifestyle factors, such as physical fitness, that lower leptin independent of adiposity may be confounding the obesity paradox. To investigate this, we evaluated whether physical fitness moderated the relationship between leptin and adiposity. We found older adults with higher fitness had lower body mass (r(39) = -0.43, p < 0.01), leptin (r(39) = -0.29, p = 0.03) and inflammation (IL-1β: (r(39) = -0.69, p < 0.01); TNF-α: (r(39) = -0.30, p = 0.03)). Fitness moderated the relationship between leptin and adiposity (F(5, 37) = 3.73, p < 0.01, R² = 0.33) to reveal the obesity paradox in moderately and high fit individuals (b = 216.24, t(37) = 1.46, p = 0.15; b= -88.10, t(37) = -0.49, p = 0.63) but not in low fit individuals. These results show the link between obesity and mortality may not be dependent on total adiposity, but rather on endocrine function and adipocyte leptin secretion. These results have important implications for older adults struggling to maintain healthy body composition and suggest that fitness may promote overall wellbeing.

The effects of moderate alterations in adrenergic activity on acute appetite regulation in obese women: A randomised crossover trial

BACKGROUND

Previous evidence has demonstrated that serum leptin is correlated with appetite in combination with, but not without, modest exercise.

AIM

The present experiments investigated the effects of exogenous adrenaline and α/β adrenoceptor blockade in combination with moderate exercise on serum leptin concentrations, appetite/satiety sensations and subsequent food intake in obese women.

METHODS

A total of 10 obese women ((mean ± SEM), age: 50 (1.9) years, body mass index 36 (4.1) kg/m2, waist 104.8 (4.1) cm) participated in two separate, double-blind randomised experimental trials. Experiment 1: moderate exercise after α/β adrenergic blocker (labetalol, 100 mg orally) versus moderate exercise plus placebo; experiment 2: adrenaline infusion for 20 minutes versus saline infusion. Appetite/satiety and biochemistry were measured at baseline, pre- and immediately post-intervention, then 1 hour post-intervention (i.e., before dinner). Food intake was assessed via ad libitum buffet-style dinner.

RESULTS

No differences were found in appetite/satiety, subsequent food intake or serum leptin in any of the studies (experiment 1 or experiment 2). In experiment 1, blood glucose was higher (p < 0.01) and plasma free fatty acids lower (p = 0.04) versus placebo. In experiment 2, plasma free fatty acids (p < 0.05) increased after adrenaline versus saline infusion.

CONCLUSIONS

Neither inhibition of exercise-induced adrenergic activity by combined α/β adrenergic blockade nor moderate increases in adrenergic activity induced by intravenous adrenaline infusion affected acute appetite regulation.

Zoladz J, Brzozowski T. Effect of Acute Sprint Exercise on Myokines and Food Intake Hormones in Young Healthy Men

Physical exercise is known to influence hormonal mediators of appetite, but the effect of short-term maximal intensity exercise on plasma levels of appetite hormones and cytokines has been little studied. We investigated the effect of a 30 s Wingate Test, followed by a postprandial period, on appetite sensations, food intake, and appetite hormones. Twenty-six physically active young males rated their subjective feelings of hunger, prospective food consumption, and fatigue on visual analogue scales at baseline, after exercise was completed, and during the postprandial period. Blood samples were obtained for the measurement of nesfatin-1, ghrelin, leptin, insulin, pancreatic polypeptide (PP), human growth factor (hGH) and cytokine interleukin-6 (IL-6), irisin and plasma lactate concentrations, at 30 min before exercise, immediately (210 s) after exercise, and 30 min following a meal and at corresponding times in control sedentary males without ad libitum meal intake, respectively. Appetite perceptions and food intake were decreased in response to exercise. Plasma levels of irisin, IL-6, lactate, nesfatin-1 and ghrelin was increased after exercise and then it was returned to postprandial/control period in both groups. A significant rise in plasma insulin, hGH and PP levels after exercise was observed while meal intake potentiated this response. In conclusion, an acute short-term fatiguing exercise can transiently suppress hunger sensations and food intake in humans. We postulate that this physiological response involves exercise-induced alterations in plasma hormones and the release of myokines such as irisin and IL-6, and supports the notion of existence of the skeletal muscle-brain-gut axis. Nevertheless, the detailed relationship between acute exercise releasing myokines, appetite sensations and impairment of this axis leading to several diseases should be further examined.

The effects of exercise and ambient temperature on dietary intake, appetite sensation, and appetite regulating hormone concentrations

BACKGROUND

It is not clear whether the frequently reported phenomenon of exercise-induced anorexia is exacerbated or blunted in warm or cold environments. Therefore, this study investigated the effects of exercise in three different environmental temperatures vs. rest, on perceptions of appetite, appetite regulating hormones, and food intake.

METHODS

In a randomized repeated-measures design, 18 Canadian Armed Forces members (14 male, 4 female) completed four 8-h trials in a thermally-controlled chamber: one 8-h resting trial at 21 °C (Sedentary); and three trials where participants completed two 2-h circuits of standardized military tasks interspersed with two 2-h rest periods, once at 30 °C (Hot), once at 21 °C (Temperate), and once at - 10 °C (Cold). Participants consumed military field rations ad libitum and had their appetite assessed with visual analogue scales. Plasma concentrations of GLP-1, PYY, acylated ghrelin, and leptin were also determined.

RESULTS

Appetite was perceived as being suppressed in the heat compared to the cold (p < 0.05). While neither exercise nor environmental temperature altered circulating GLP-1 levels, exercise in all environments increased blood concentrations of PYY (p < 0.05). Leptin concentrations were elevated in the heat and diminished in the cold (p < 0.05), and acylated ghrelin concentrations were affected by both exercise and ambient temperature resulting in Sedentary = Cold>Temperate = Hot (p < 0.05). Contrary to the changes in appetite perceptions and hormonal concentrations, dietary intake was not different between conditions (p > 0.05). Relative energy intake (total 24 h energy intake minus 24 h energy expenditure) on the other hand, was significantly higher during the Sedentary condition than it was during any of the active conditions (p < 0.05). Most (83%) of the participants were in a positive energy balance during the Sedentary condition, whereas during most (80%) of the active conditions (Hot, Temperate, Cold) participants were in a negative energy balance.

CONCLUSIONS

In this study where food was freely available, variations in ambient temperature, exercise vs. rest, appetite-regulating hormone concentrations, and subjective appetite sensation were not associated with any changes in dietary intake within 24-h of acute, prolonged exercise.

Acute and Chronic Effects of Exercise on Appetite, Energy Intake, and Appetite-Related Hormones: The Modulating Effect of Adiposity, Sex, and Habitual Physical Activity

Exercise facilitates weight control, partly through effects on appetite regulation. Single bouts of exercise induce a short-term energy deficit without stimulating compensatory effects on appetite, whilst limited evidence suggests that exercise training may modify subjective and homeostatic mediators of appetite in directions associated with enhanced meal-induced satiety. However, a large variability in responses exists between individuals. This article reviews the evidence relating to how adiposity, sex, and habitual physical activity modulate exercise-induced appetite, energy intake, and appetite-related hormone responses. The balance of evidence suggests that adiposity and sex do not modify appetite or energy intake responses to acute or chronic exercise interventions, but individuals with higher habitual physical activity levels may better adjust energy intake in response to energy balance perturbations. The effect of these individual characteristics and behaviours on appetite-related hormone responses to exercise remains equivocal. These findings support the continued promotion of exercise as a strategy for inducing short-term energy deficits irrespective of adiposity and sex, as well as the ability of exercise to positively influence energy balance over the longer term. Future well-controlled studies are required to further ascertain the potential mediators of appetite responses to exercise.

An acute bout of cycling does not induce compensatory responses in pre-menopausal women not using hormonal contraceptives

There is a clear need to improve understanding of the effects of physical activity and exercise on appetite control. Therefore, the acute and short-term effects (three days) of a single bout of cycling on energy intake and energy expenditure were examined in women not using hormonal contraceptives. Sixteen active (n = 8) and inactive (n = 8) healthy pre-menopausal women completed a randomised crossover design study with two conditions (exercise and control). The exercise day involved cycling for 1 h (50% of maximum oxygen uptake) and resting for 2 h, whilst the control day comprised 3 h of rest. On each experimental day participants arrived at the laboratory fasted, consumed a standardised breakfast and an ad libitum pasta lunch. Food diaries and combined heart rate-accelerometer monitors were used to assess free-living food intake and energy expenditure, respectively, over the subsequent three days. There were no main effects or condition (exercise vs control) by group (active vs inactive) interaction for absolute energy intake (P > 0.05) at the ad libitum laboratory lunch meal, but there was a condition effect for relative energy intake (P = 0.004, η_p² = 0.46) that was lower in the exercise condition (1417 ± 926 kJ vs. 2120 ± 923 kJ). Furthermore, post-breakfast satiety was higher in the active than in the inactive group (P = 0.005, η_p² = 0.44). There were no main effects or interactions (P > 0.05) for mean daily energy intake, but both active and inactive groups consumed less energy from protein (14 ± 3% vs. 16 ± 4%, P = 0.016, η_p² = 0.37) and more from carbohydrate (53 ± 5% vs. 49 ± 7%, P = 0.031, η_p² = 0.31) following the exercise condition. This study suggests that an acute bout of cycling does not induce compensatory responses in active and inactive women not using hormonal contraceptives, while the stronger satiety response to the standardised breakfast meal in active individuals adds to the growing literature that physical activity helps improve the sensitivity of short-term appetite control.

Comparison between the effect of 6 weeks of morning or evening aerobic exercise on appetite and anthropometric indices: a randomized controlled trial

Several studies have shown that exercise is directly related to creating negative energy balance and changes in appetite. However, few studies have examined the effect of exercise time during the day on these factors. The aim of the present study was to demonstrate the effect of 6 weeks of morning and evening aerobic exercise on appetite and anthropometric indices. A total of 48 overweight females were recruited to this clinical trial. By the time of exercise, they were divided into two groups (morning or evening) and performed 6 weeks of exercise with a target heart rate on the ventilatory threshold. Appetite change, calorie intake and anthropometric indices were assessed. Consistent changes in appetite scores were not found during the 6 weeks (P > 0.05). Calorie consumption of the morning group decreased significantly more than that of the evening group (P = 0.02) during the 6 weeks. In addition, significant changes in body weight, body mass index, abdominal skin fold thickness and abdominal circumference were seen in the morning group. It appears that moderate- to high-intensity aerobic exercise in the morning could be considered a more effective programme than evening exercise on appetite control, calorie intake and weight loss in inactive overweight women. However, the limitations of the study, such as short-term duration, should be noticed.

Exercise, Appetite and Weight Control: Are There Differences between Men and Women?

Recent years have witnessed significant research interest surrounding the interaction among exercise, appetite and energy balance, which has important implications for health. The majority of exercise and appetite regulation studies have been conducted in males. Consequently, opportunities to examine sex-based differences have been limited, but represent an interesting avenue of inquiry considering postulations that men experience greater weight loss after exercise interventions than women. This article reviews the scientific literature relating to the acute and chronic effects of exercise on appetite control in men and women. The consensus of evidence demonstrates that appetite, appetite-regulatory hormone and energy intake responses to acute exercise do not differ between the sexes, and there is little evidence indicating compensatory changes occur after acute exercise in either sex. Limited evidence suggests women respond to the initiation of exercise training with more robust compensatory alterations in appetite-regulatory hormones than men, but whether this translates to long-term differences is unknown. Current exercise training investigations do not support sex-based differences in appetite or objectively assessed energy intake, and increasing exercise energy expenditure elicits at most a partial energy intake compensation in both sexes. Future well-controlled acute and chronic exercise studies directly comparing men and women are required to expand this evidence base.

Altered gut and adipose tissue hormones in overweight and obese individuals: cause or consequence?

The aim of this article is to review the research into the main peripheral appetite signals altered in human obesity, together with their modifications after body weight loss with diet and exercise and after bariatric surgery, which may be relevant to strategies for obesity treatment. Body weight homeostasis involves the gut–brain axis, a complex and highly coordinated system of peripheral appetite hormones and centrally mediated neuronal regulation. The list of peripheral anorexigenic and orexigenic physiological factors in both animals and humans is intimidating and expanding, but anorexigenic glucagon-like peptide 1 (GLP-1), cholecystokinin (CCK), peptide YY (PYY) and orexigenic ghrelin from the gastrointestinal tract, pancreatic polypeptide (PP) from the pancreas and anorexigenic leptin from adiposites remain the most widely studied hormones. Homeostatic control of food intake occurs in humans, although its relative importance for eating behaviour is uncertain, compared with social and environmental influences. There are perturbations in the gut–brain axis in obese compared with lean individuals, as well as in weight-reduced obese individuals. Fasting and postprandial levels of gut hormones change when obese individuals lose weight, either with surgical or with dietary and/or exercise interventions. Diet-induced weight loss results in long-term changes in appetite gut hormones, postulated to favour increased appetite and weight regain while exercise programmes modify responses in a direction expected to enhance satiety and permit weight loss and/or maintenance. Sustained weight loss achieved by bariatric surgery may in part be mediated via favourable changes to gut hormones. Future work will be necessary to fully elucidate the role of each element of the axis, and whether modifying these signals can reduce the risk of obesity.

Effects of an acute bout of aerobic exercise on immediate and subsequent three-day food intake and energy expenditure in active and inactive pre-menopausal women taking oral contraceptives

This study examined the effects of an acute bout of exercise of low-intensity on food intake and energy expenditure over four days in women taking oral contraceptives. Twenty healthy, active (n = 10) and inactive (n = 10) pre-menopausal women taking oral contraceptives completed two conditions (exercise and control), in a randomised, crossover fashion. The exercise experimental day involved cycling for one hour at an intensity equivalent to 50% of maximum oxygen uptake and two hours of rest. The control condition comprised three hours of rest. Participants arrived at the laboratory fasted overnight; breakfast was standardised and an ad libitum pasta lunch was consumed on each experimental day. Participants kept a food diary to measure food intake and wore an Actiheart to measure energy expenditure for the remainder of the experimental days and over the subsequent 3 days. There was a condition effect for absolute energy intake (exercise vs.

CONTROL

3363 ± 668 kJ vs. 3035 ± 752 kJ; p = 0.033, d = 0.49) and relative energy intake (exercise vs.

CONTROL

2019 ± 746 kJ vs. 2710 ± 712 kJ; p <0.001, d = -1.00) at the ad libitum lunch. There were no significant differences in energy intake over the four days in active participants and there was a suppression of energy intake on the first day after the exercise experimental day compared with the same day of the control condition in inactive participants (mean difference = -1974 kJ; 95% CI -1048 to -2900 kJ, p = 0.002, d = -0.89). There was a group effect (p = 0.001, d = 1.63) for free-living energy expenditure, indicating that active participants expended more energy than inactive participants during this period. However, there were no compensatory changes in daily physical activity energy expenditure. These results support the use of low-intensity aerobic exercise as a method to induce a short-term negative energy balance in inactive women taking oral contraceptives.

Plasma leptin concentrations are highly correlated to emotional states throughout the day

Previous work has shown that leptin appears to regulate the plasma levels of hormones such as adrenocorticotropic hormone (ACTH) and cortisol in humans and that it has antidepressant effects in animals. It is unknown whether fluctuations in circulating leptin levels are correlated to changes in human emotions. This study was conducted to determine whether minute-to-minute fluctuations in the plasma concentrations of human leptin were associated with psychological variables. Leptin was sampled every 7 min throughout the day in 10 healthy subjects (five men and five women) studied in a clinical research center, and visual analog scales were applied every hour. We found highly significant correlations between fluctuations in plasma leptin concentrations and three psychological variables: sadness, carbohydrate craving and social withdrawal. We showed that during the course of the day increases in leptin levels are associated with decreased search for starchy foods, decreased feelings of sadness and increased social withdrawal. Our findings support the hypothesis that during the course of the day as leptin levels increase individuals subjectively feel happier (less sad) and have less inclination to interact socially. Conversely, when leptin levels decrease, we show increases in sadness and social cooperation, which might facilitate the search for food. We suggest that increased human leptin levels may promote positive feelings and that decreased leptin levels might modulate inner states that motivate and facilitate the search for nutrients.

Exercise and negative energy balance in males who perform mental work

BACKGROUND

Although energy expenditure during mental work is not higher than energy expenditure at rest, a stressful mental task is related to an increase in energy intake. It is suggested that mental work produces physiological changes, thereby influencing food intake.

OBJECTIVE

Because physical activity can influence hunger, the aim of the study was to determine if the introduction of an active pause could counteract the negative effects of mental work on energy intake and energy balance.

METHOD

Twelve male students, of normal weight, between 15 and 20 years old were evaluated. All subjects participated in three different sessions realized in a randomized order: (i) without pause = relaxation/mental work/meal; (ii) relaxation pause = mental work/relaxation/meal; and (iii) exercise pause = mental work/exercise/meal. Energy expenditure was measured with indirect calorimetry, energy intake was measured with a cold buffet-type meal of 40 items, and appetite-related sensations were measured with visual analogue scales. The effect of introducing an active pause in energy intake and energy balance was studied.

RESULTS

The introduction of an active pause did not influence energy intake; although, higher appetite-related sensations were observed (16-26 mm on a 150-mm scale; P < 0.05). After accounting for the energy expenditure related to physical activity, a lower energy balance was measured for the exercise pause visit compared with the visit without a pause (-1137 kJ; P < 0.05).

CONCLUSION

This study indicates that being active between mental work and a meal could represent a strategy to create a negative energy balance following mental work via an increased energy expenditure and a maintenance of energy intake. Globally, these results could help individuals attain and/or maintain a healthy body weight in a context where mental work is omnipresent.

Creating an acute energy deficit without stimulating compensatory increases in appetite: is there an optimal exercise protocol?

Recent years have witnessed significant interest from both the scientific community and the media regarding the influence of exercise on subsequent appetite and energy intake responses. This review demonstrates a consensus among the majority of scientific investigations that an acute bout of land-based endurance exercise does not stimulate any compensatory increases in appetite and energy intake on the day of exercise. Alternatively, preliminary evidence suggests that low volume, supramaximal exercise may stimulate an increase in appetite perceptions during the subsequent hours. In accordance with the apparent insensitivity of energy intake to exercise in the short term, the daily energy balance response to exercise appears to be primarily determined by the energy cost of exercise. This finding supports the conclusions of recent training studies that the energy expenditure of exercise is the strongest predictor of fat loss during an exercise programme.

Effect of chronic exercise on appetite control in overweight and obese individuals

PURPOSE

The effect of exercise on body mass is likely to be partially mediated through changes in appetite control. However, no studies have examined the effect of chronic exercise on obestatin and cholecystokinin (CCK) plasma concentrations or the sensitivity to detect differences in preload energy in obese individuals. The objective of this study was to investigate the effects of chronic exercise on 1) fasting and postprandial plasma concentrations of obestatin, CCK, leptin, and glucose insulinotropic peptide (GIP) and 2) the accuracy of energy compensation in response to covert preload manipulation.

METHODS

This study used a 12-wk supervised exercise program in 22 sedentary overweight/obese individuals. Fasting/postprandial plasma concentrations of obestatin, CCK, leptin, and GIP were assessed before and after the intervention. Energy compensation at a 30-min test meal after a high-energy (607 kcal) or a low-energy (246 kcal) preload and for the rest of the day (cumulative energy intake [EI]) was also measured.

RESULTS

There was a significant reduction in the plasma concentration of fasting plasma GIP and both fasting and postprandial leptin concentrations after the exercise intervention (P < 0.05 for all). No significant changes were observed for CCK or obestatin. A significant preload-exercise interaction (P = 0.011) was observed on cumulative EI and energy compensation for the same period (-87% ± 196% vs 68% ± 165%, P = 0.011). Weight loss (3.5 ± 1.4 kg, P < 0.0001) was not correlated with changes in energy compensation.

CONCLUSIONS

This study suggests that exercise improves the accuracy of compensation for previous EI, independent of weight loss. Unexpectedly, and in contrast to GIP and leptin, exercise-induced weight loss had no effect on obestatin or CCK concentrations.

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.

The Interaction Between Exercise, Appetite, and Food Intake

Exercise could indirectly affect body weight by exerting changes on various components of appetite control, including nutrient and taste preferences, meal size and frequency, and the drive to eat. This review summarizes the evidence on how exercise affects appetite and eating behavior and in particular answers the question, “Does exercise induce an increase in food intake to compensate for the increase in energy expenditure?” Evidence will be presented to demonstrate that there is no automatic increase in food intake in response to acute exercise and that the response to repeated exercise is variable. The review will also identify areas of further study required to explain the variability. One limitation with studies that assess the efficacy of exercise as a method of weight control is that only mean data are presented—the individual variability tends to be overlooked. Recent evidence highlights the importance of characterizing the individual variability by demonstrating exercise-induced changes in appetite. Individuals who experience lower than theoretically predicted reductions in body weight can be characterized by hedonic (eg, pleasure) and homeostatic (eg, hunger) features.

Appetite regulation in response to sitting and energy imbalance

The impact of sitting and energy imbalance on appetite and appetite-regulating hormones (acylated ghrelin and leptin) was assessed in response to 1 day of sitting, with and without changes in energy intake. Fourteen men and women completed each of three 24-h conditions: high energy expenditure (standing) with energy balance (STAND), low energy expenditure (sitting) with energy surplus (SIT), and sitting with energy balance (SIT-BAL). Ghrelin, leptin, and appetite were measured in the fasted state and following a standardized meal. In the fasted state, there were no differences among conditions. Following the meal, ghrelin was lower in SIT than in STAND, with no change in appetite. When intake was reduced (SIT-BAL), the decrease in ghrelin when sitting was attenuated, hunger increased, and fullness decreased. SIT led to lower ghrelin concentrations in the men, whereas in the women, leptin increased. SIT-BAL led to an increase in ghrelin in the men but attenuated the leptin response, reduced ghrelin, increased hunger, and decreased fullness in the women. Because a dramatic reduction in energy expenditure was not accompanied by reduced appetite, prolonged sitting may promote excess energy intake, leading to weight gain in both men and women.

Using a novel computer-based approach to assess the acute effects of exercise on appetite-related measures

Measuring food intake using standard buffet meals can be complicated by sensory and external cues which can alter energy intake. The present study was designed to examine the effects of acute exercise on non-metabolic factors related to appetite and food intake using a computer-based assessment. Twenty-seven men and women participated in two sessions in random order: 60-min walking on the treadmill (exercise trial; EX) or seated rest (control trial; CON). Subjective hunger and fullness, food liking, food utility, and ideal portion size were assessed before and immediately after exercise or rest, and hourly for 2 h. The findings showed that an acute bout of moderate intensity exercise had an anorexigenic effect; characterised by diminished hunger (-17.4%, p=0.004) and lower prospective ideal portion size (-7.7%, p=0.003) compared to no exercise. This novel, computer-based assessment, is a useful alternative to buffet meals setting and allows for the determination of non-metabolic factors associated with feeding behaviour in relation to exercise.

Influence of brisk walking on appetite, energy intake, and plasma acylated ghrelin

PURPOSE

This study examined the effect of an acute bout of brisk walking on appetite, energy intake, and the appetite-stimulating hormone-acylated ghrelin.

METHODS

Fourteen healthy young males (age 21.9 +/- 0.5 yr, body mass index 23.4 +/- 0.6 kg x m(-2), (.)VO2max 55.9 +/- 1.8 mL x kg(-1) x min(-1); mean +/- SEM) completed two 8-h trials (brisk walking and control) in a randomized counterbalanced fashion. The brisk walking trial commenced with 60 min of subjectively paced brisk walking on a level-motorized treadmill after which participants rested for 7 h. Participants rested for the duration of the control trial. Ad libitum buffet meals were offered twice during main trials (1.5-2 and 5-5.5 h). Appetite (hunger, fullness, satisfaction, and prospective food consumption) was assessed at 30-min intervals throughout. Levels of acylated ghrelin, glucose, insulin, and triacylglycerol were determined from plasma.

RESULTS

Sixty minutes of brisk walking (7.0 +/- 0.1 km x h(-1) yielded a net (exercise minus resting) energy expenditure of 2008 +/- 134 kJ, yet it did not significantly influence appetite, energy/macronutrient intake, or the plasma concentration of acylated ghrelin either during or after exercise(P > 0.05). Participants did not compensate for energy expended during walking, therefore a deficit in energy was induced (1836 kJ, 439 kcal) relative to control.

CONCLUSIONS

This study demonstrates that, despite inducing a moderate energy deficit, an acute bout of subjectively paced brisk walking does not elicit compensatory responses in acylated ghrelin, appetite, or energy intake. This finding lends support for a role of brisk walking in weight management.

Plasma ghrelin levels during exercise — Effects of intensity and duration

Ghrelin, a recently discovered hormone of gastric origin has been shown to stimulate appetite and food intake. In man it is considered to play a role in energy homeostasis and regulation of somatropic function. As exercise affects hunger/satiety sensations and food intake, at least under some experimental conditions, we investigated the effect of exercise intensity and duration on ghrelin release and subsequent ad libitum food intake in normal weight subjects. Bicycle exercise on an ergometer for 30 min at 50 W which was below the aerob-anaerobic threshold led to an increase of ghrelin which remained unchanged during the higher intensity at 100 W. Respective hunger/satiety ratings and subsequent food intake and postprandial ghrelin suppression were identical and not different from controls. In a second group 7 subjects cycled at 50 W for 30, 60 and 120 min, respectively. Ghrelin concentrations rose significantly by 50-70 pg/ml above baseline for the respective period of exercise. While postexercise premeal ghrelin levels were not significantly different subsequent food intake after 120 min of cycling was significantly greater compared to control, 30 min and 60 min exercise, respectively. The present data suggest that low rather than high-intensity exercise stimulates ghrelin levels independent of exercise duration. Stimulation of food intake during prolonged exercise is most likely not due to changes of ghrelin.

Prenatal programming of postnatal obesity: fetal nutrition and the regulation of leptin synthesis and secretion before birth

The introduction of the process of nutritional screening into clinical standards has been driven by the increasing awareness of the prevalence of undernutrition in acute and primary care, along with its associated morbidity and mortality. However, the increasing prevalence of obesity in the general population suggests that an increased number of patients admitted to hospital will be obese. Increased morbidity has also been reported in the injured obese patient and may be associated with poor nutritional support. This situation may occur because the profound metabolic disturbances accompanying trauma in this group are not recognised, and subsequent feeding practices are inappropriate. Screening tools currently classify patients by using simple markers of assessment at the whole-body level, such as BMI. Subsequently, patients are identified as at risk only if they are undernourished. Such comparisons would by definition classify injured obese patients as at minimal or no nutritional risk, and they would therefore be less likely to be re-screened. This approach could result in potential increases in morbidity, length of rehabilitation and consequent length of hospital stay. It is likely that the identification of potential risk in obese injured patients goes beyond the measurement of such indices as BMI and percentage weight loss, which are currently utilised by the majority of screening processes.

The effect of advice to walk 2000 extra steps daily on food intake

BACKGROUND

It is currently unclear how physical activity and diet interact within the ranges of activity seen in the general population. This study aimed to establish whether a small, acute, increase in physical activity would lead to compensatory change in energy intake and nutrient balance, and to provide power analysis data for future research in this field.

METHOD

Twelve participants were studied over 7 days of habitual activity and 2 weeks after instruction to increase physical activity by 2000 steps per day. Physical activity was assessed using a diary, the 'activPAL' activity monitor and a pedometer. Dietary analyses from prospective food diaries were compared between the first and third weeks.

RESULTS

Participants increased step-counts (+2600 steps per day, P = 0.008) and estimated energy expenditure (+300-1000 kJ day(-1), P = 0.002) but did not significantly change their energy intake, dietary composition or number of meals per day. From reverse power analysis 38 participants would be needed to exclude a change in energy intake of 400 kJ day(-1) with 90% power at P < 0.05; 400 kJ day(-1) would compensate for a 2000 steps per day increase in physical activity.

CONCLUSION

These results did not demonstrate any compensatory increase in food consumption when physical activity was increased by walking an average of 2600 additional steps per day. Power analysis indicates that a larger study (n = 38) will be necessary to exclude such an effect with confidence.

Acute effects of a single exercise class on appetite, energy intake and mood. Is there a time of day effect?

This study aimed to investigate the acute effects of a single exercise class on appetite sensations, energy intake and mood, and to determine if there was a time of day effect. Twelve healthy, young, normal weight females, who were non-regular exercisers, participated in four trials: morning control, morning exercise, evening control and evening exercise. Exercise trials were a one-hour class of aerobic and muscle conditioning exercise of varying intensities, to music. Control trials were a one-hour rest. Ratings of perceived exertion were significantly greater during the warm-up and muscle conditioning parts of the morning exercise trial compared to those of the evening exercise trial. Although both exercise trials, compared to control trials, produced an increase in appetite sensations, they did not alter energy intake and produced a decrease in 'relative' energy intake. In relation to mood, both exercise trials increased positive affect and decreased negative affect. These results suggest that a single exercise class, representative of that offered by many sports centres, regardless of whether it is performed in the morning or evening produces a short-term negative energy balance and improves mood in normal weight women. However, when this type of exercise was performed in the morning it was perceived to require more effort.

Effect of three treatment schedules of recombinant methionyl human leptin on body weight in obese adults: a randomized, placebo-controlled trial

AIM

The aim of this study was to evaluate the effect on body weight and safety of subcutaneously administered recombinant leptin in obese adults and to evaluate whether the timing of recombinant leptin administration influences efficacy.

METHODS

A randomized, double-blind, placebo-controlled, multicentre study was designed, comprising of a 3-week dietary lead-in followed by a 12-week leptin or placebo treatment period. A total of 284 overweight and obese (body mass index 27-37.0 kg/m(2)) predominantly white (98%) women (66%) and men (34%) with a mean (+/-s.d.) 46.8+/-10.4 years of age were randomized into three treatment groups with three matching placebo groups. Recombinant leptin was administered by subcutaneous injection [10 mg/morning, 10 mg/evening or 20 mg/day (10 mg twice daily)]. Patients were counselled at baseline to reduce dietary intake by 2,100 kJ/day (500 kcal/day), and dietary advice was reinforced every 2-4 weeks.

RESULTS

No statistically significant change in body weight occurred with recombinant leptin treatment compared with placebo treatment in any treatment group. No clinically significant adverse effects were observed with the exception of an increase in injection-site reactions in patients treated with recombinant leptin (83%) vs. placebo (36%).

CONCLUSIONS

Administration of recombinant leptin to an overweight and obese population, in addition to a mildly energy-restricted diet, was not efficacious in terms of weight loss at the doses and schedules studied. The hypothesis that nocturnal administration of recombinant leptin might have a specific effect on weight loss was not supported.

Interactions of metabolic hormones, adipose tissue and exercise

Physiological and psychological systems work together to determine energy intake and output, and thus maintain adipose tissue. In addition, adipose tissue secretes leptin and cytokines, which induces satiety and has been linked to catecholamines, cortisol, insulin, human growth hormone, thyroid hormones, gonadotropin and lipolysis. Thus, adipose tissue is acted upon by a number of physiological stimuli, including hormones, and simultaneously, is an active component in the regulation of its own lipid content. All of the hormones mentioned above are associated with each other and respond to exercise and exercise training. Thus, exercise is one of the major links between the hormonal modulators of energy intake and output. It appears that the sympathetic nervous system and the catecholamines are key components facilitating the lipolytic activity during exercise. These two neuroendocrine factors directly affect adipose metabolism and metabolic hormones that influence adipose metabolism. Acute low- and moderate-intensity exercise causes hormonal changes that facilitate lipolytic activity. Exercise training reduces these hormonal responses, but the sensitivity to these hormones increases so that lipolysis may be facilitated. Large amounts of adipose tissue blunt the metabolic hormonal responses to exercise, but the sensitivity of these hormones is increased; thus maintaining normal lipolytic activity. Although the physiological role of the endocrine system during exercise and training is significant, other training effects may have as great, or greater influence on lipolytic activity in adipose tissue.

Maternal nutritional programming of fetal adipose tissue development: Long-term consequences for later obesity

As obesity reaches epidemic levels in the United States there is an urgent need to understand the developmental pathways leading to this condition. Obesity increases the risk of hypertension and diabetes, symptoms of which are being seen with increased incidence in children. Adipocyte development begins in the fetus and, in contrast to all other tissues whose growth ceases in late juvenile life, it has the capacity for "unlimited" growth. In normal healthy individuals, the increase in fat mass with age is accompanied by a parallel increase in cortisol sensitivity, i.e., increased glucocorticoid receptor abundance and increased activity of the enzyme 11beta hydroxysteroid dehydrogenase type 1. Enhanced adipocyte sensitivity to cortisol is promoted in offspring born to mothers that were nutrient-restricted in utero in conjunction with increased peroxisome proliferator activated receptor alpha. This adaptation only appears to be associated with greater fat mass in the offspring when maternal nutrient restriction is confined to late gestation, coincident with the period of maximal fetal growth. In these offspring, increased fat mass is accompanied by glucose intolerance and insulin resistance, in conjunction with an adipose tissue specific reduction in glucose transporter 4 abundance. In conclusion, changes in maternal and, therefore, fetal nutrient supply at specific stages of gestation have the potential to substantially increase the risk of those offspring becoming obese in later life. The extent to which changes in dietary habits, both during pregnancy and in later life, may act to contribute to the current explosion in childhood and adult obesity remains a scientific and public health challenge to us all.

Metabolic and behavioral characteristics of metabolically obese but normal-weight women

A unique subset of individuals termed metabolically obese but normal weight (MONW) has been identified. These young women are potentially at increased risk for development of the metabolic syndrome despite their young age and normal body mass index. We seek to determine metabolic and behavioral factors that could potentially distinguish MONW women from young women with a normal metabolic profile.Ninety-six women were classified as MONW (n = 12) or non-MONW (n = 84) based on a cut point of insulin sensitivity (as estimated by the homeostasis model assessment). Potentially distinguishing phenotypes between groups measured included serum lipids, ghrelin, leptin, adiponectin, body composition and body fat distribution, resting and physical activity energy expenditure, peak oxygen uptake, dietary intake, dietary behavior, and family history and lifestyle variables. Despite a similar body mass index between groups, MONW women showed higher percent body fat, lower fat-free mass, lower physical activity energy expenditure, and lower peak oxygen uptake than non-MONW women. Plasma cholesterol level was higher in MONW women, whereas no differences were noted for other blood lipids, ghrelin, leptin, adiponectin, and resting energy expenditure. MONW women had lower dietary restraint scores than non-MONW women, but no differences were noted in disinhibition, hunger, and dietary intake. Stepwise regression analysis performed on all subjects showed that 33.5% of the unique variance of the homeostasis model assessment was explained with the variables of percentage of body fat (17.1%), level of dietary restraint (10.4%), and age (6%). Both metabolic and dietary behavioral variables contribute to the deleterious metabolic profile of MONW women. They display lower insulin sensitivity due potentially to a cluster of sedentary behavior patterns that contribute to their higher adiposity. Furthermore, cognitive attitudes toward food (i.e. dietary restraint) and concomitant lifestyle behaviors may play a role in regulating insulin sensitivity in MONW women.