PubMed Health⌕ Search

Biomedical subjects

N A King

Publications and source records attributed to N A King.

At least 19 recordsLinked to original sources
PubMed2006

Characterization of obese individuals who claim to detect no relationship between their eating pattern and sensations of hunger or fullness.

OBJECTIVE: To study the phenomenon that obese subjects show considerable individual variability in their reported relationships between eating and sensations of hunger and fullness. DESIGN: A laboratory study of the relationship between eating behaviour traits and the episodic oscillations in sensations of hunger and fullness in response to obligatory, fixed energy breakfast (481 kcal) and lunch (675 kcal) meals. SUBJECTS: Obese subjects were divided into two groups based on their responses to four 'screening' questions associated with their habitual experience of hunger and fullness sensations before and after eating: those who experienced sensations of hunger and fullness related to eating (Related-R; n=20, body mass index (BMI)=42.4 kg/m(2)) and those for whom eating was not related to hunger or fullness sensations (Unrelated - UR; n=19, BMI=41.3 kg/m(2)). In addition, a control, lean group (Control - C; n=14, BMI=22.6 kg/m(2)) who experienced sensations of hunger and fullness related to eating was studied. MEASUREMENTS: The Three-Factor Eating Questionnaire (TFEQ) was used to measure the eating behaviour traits, disinhibition, restraint and hunger. Profiles of subjective appetite sensations were continuously monitored across the day using visual analogue scales. RESULTS: All groups displayed clear meal-related oscillations in subjective sensations of hunger, fullness, desire to eat and prospective consumption. In contrast, the TFEQ disinhibition and hunger scores (but not restraint scores) were significantly different (P<0.05) between the groups ((UR; D=13.5+/-0.5, H=10.0+/-0.5), R (D 7.5+/-0.6, H 6.1+/-0.4), C(D 3.7+/-0.5, H 3.7+/-0.5)). In addition, analysis of the intra-meal changes in subjective appetite sensations revealed that the UR group displayed a smaller meal-induced suppression of hunger and elevation of fullness. CONCLUSION: These data indicate that the reported relationship between eating and hunger/fullness was associated with obese individuals showing high or low disinhibition scores. In addition, the data suggest that the processes underlying disinhibition may be associated with a modulation of the recognition of meal-related satiety sensations.

Adult↗
PubMed2006

The effect of a medium-term activity- and diet-induced energy deficit on subjective appetite sensations in obese children.

OBJECTIVE: To assess the subjective appetite responses to an imposed activity- and diet-induced energy deficit during a residential intervention programme for obese children. DESIGN: A 6-week intervention of fixed, reduced dietary intake and 6 h/day of skill-based physical activity while resident in a weight loss camp. SUBJECTS: Thirty-eight obese (mean body mass index (BMI)=34.9 kg m(-2)) boys and girls (mean age 13.9+/-1.57). MEASUREMENTS: An electronic appetite rating system (EARS) was used to periodically measure subjective appetite sensations at the start (WK1) and at the end (WK6) of the camp. Subjective ratings of hunger and fullness were compared at the start and end of 6 weeks of an activity- and diet-induced-based weight loss intervention. RESULTS: At the end of the 6 weeks, the children had lost 8.4 kg in body mass. The diurnal profiles of subjective appetite sensations demonstrated clear oscillations in hunger and fullness. There was a significant increase in hunger (P<0.0001) and decrease in fullness (P<0.005) at the end (WK6) of the medium-term energy deficit. In WK6, morning ratings of hunger were higher than in WK1 (P<0.005) and the fixed energy evening meal induced a lower suppression of hunger (P<0.02). CONCLUSION: A programme of fixed, reduced-dietary intake combined with an activity and behavioural programme was successful at inducing a significant reduction in body mass in obese children. Subjective sensations of appetite were sensitive to a medium-term negative energy balance and weight loss. These data are essential as we continue to evolve methods of treatment for overweight and obese children.

Adolescent↗
PubMed2003

Cross talk between physical activity and appetite control: does physical activity stimulate appetite?

Physical activity has the potential to modulate appetite control by improving the sensitivity of the physiological satiety signalling system, by adjusting macronutrient preferences or food choices and by altering the hedonic response to food. There is evidence for all these actions. Concerning the impact of physical activity on energy balance, there exists a belief that physical activity drives up hunger and increases food intake, thereby rendering it futile as a method of weight control. There is, however, no evidence for such an immediate or automatic effect. Short (1-2 d)-term and medium (7-16 d)-term studies demonstrate that men and women can tolerate substantial negative energy balances of < or = 4 MJ energy cost/d when performing physical activity programmes. Consequently, the immediate effect of taking up exercise is weight loss (although this outcome is sometimes difficult to assess due to changes in body composition or fluid compartmentalization). However, subsequently food intake begins to increase in order to provide compensation for about 30% of the energy expended in activity. This compensation (up to 16 d) is partial and incomplete. Moreover, subjects separate into compensators and non-compensators. The exact nature of these differences in compensation and whether it is actually reflective of non-compliance with protocols is yet to be determined. Some subjects (men and women) performing activity with a cost of < or = 4 MJ/d for 14 d, show no change in daily energy intake. Conversely, it can be demonstrated that when active individuals are forced into a sedentary routine food intake does not decrease to a lower level to match the reduced energy expenditure. Consequently, this situation creates a substantial positive energy balance accompanied by weight gain. The next stage is to further characterize the compensators and non-compensators, and to identify the mechanisms (physiological or behavioural) that are responsible for the rate of compensation and its limits.

Anorexia↗
PubMed2002

Differences in postprandial responses to fat and carbohydrate loads in habitual high and low fat consumers (phenotypes).

The present study investigated metabolic responses to fat and carbohydrate ingestion in lean male individuals consuming an habitual diet high or low in fat. Twelve high-fat phenotypes (HF) and twelve low-fat phenotypes (LF) participated in the study. Energy intake and macronutrient intake variables were assessed using a food frequency questionnaire. Resting (RMR) and postprandial metabolic rate and substrate oxidation (respiratory quotient; RQ) were measured by indirect calorimetry. HF had a significantly higher RMR and higher resting heart rate than LF. These variables remained higher in HF following the macronutrient challenge. In all subjects the carbohydrate load increased metabolic rate and heart rate significantly more than the fat load. Fat oxidation (indicated by a low RQ) was significantly higher in HF than in LF following the fat load; the ability to oxidise a high carbohydrate load did not differ between the groups. Lean male subjects consuming a diet high in fat were associated with increased energy expenditure at rest and a relatively higher fat oxidation in response to a high fat load; these observations may be partly responsible for maintaining energy balance on a high-fat (high-energy) diet. In contrast, a low consumer of fat is associated with relatively lower energy expenditure at rest and lower fat oxidation, which has implications for weight gain if high-fat foods or meals are periodically introduced to the diet.

Adult↗
PubMed2001

A novel technique to demonstrate disturbed appetite profiles in haemodialysis patients.

BACKGROUND: Malnutrition is common among dialysis patients and is associated with an adverse outcome. One cause of this is a persistent reduction in nutrient intake, suggesting an abnormality of appetite regulation. METHODS: We used a novel technique to describe the appetite profile in 46 haemodialysis (HD) patients and 40 healthy controls. The Electronic Appetite Rating System (EARS) employs a palmtop computer to collect hourly ratings of motivation to eat and mood. We collected data on hunger, desire to eat, fullness, and tiredness. HD subjects were monitored on the dialysis day and the interdialytic day. Controls were monitored for 1 or 2 days. RESULTS: Temporal profiles of motivation to eat for the controls were similar on both days. Temporal profiles of motivation to eat for the HD group were lower on the dialysis day. Mean HD scores were not significantly different from controls. Dietary records indicated that dialysis patients consumed less food than controls. CONCLUSIONS: Our data indicate that the EARS can be used to monitor subjective appetite states continuously in a group of HD patients. A HD session reduces hunger and desire to eat. Patients feel more tired after dialysis. This does not correlate with their hunger score, but does correlate with their fullness rating. Nutrient intake is reduced, suggesting a resetting of appetite control for the HD group. The EARS may be useful for intervention studies.

Adult↗
PubMed2000

Selective effects of acute exercise and breakfast interventions on mood and motivation to eat.

The effects of exercise and breakfast manipulations on mood and motivation to eat were assessed in 11 healthy females who were regular exercisers and habitual breakfast eaters. The study involved a two by two repeated-measures design, with exercise (or no exercise) and a high-energy breakfast (or low-energy breakfast) as the repeated measures. The exercise or no-exercise session (0800 h) was followed by consumption of the low- or high-energy breakfast (0900 h). An ad libitum lunch test meal was provided 4 hours after the beginning of the exercise session (1200 h). Mood and motivation to eat were continuously tracked from 0800 until 1700 h by an electronic appetite ratings system (EARS). In general, morning subjective mood states (e.g., contentment) were significantly lower in the low-energy breakfast condition, but exercise reversed this effect. Exercise also significantly decreased feelings of lethargy, independent of the breakfast condition. Desire-to-eat and fullness ratings were significantly increased in the low-energy breakfast and high-energy breakfast conditions, respectively. Impairments of mood disappeared in the afternoon after consumption of an ad libitum lunch. In these healthy young adults, the condition inducing the largest energy deficit (exercise and low-energy breakfast) was not associated with the lowest mental states.

Adult↗
PubMed2000

No energy compensation at the meal following exercise in dietary restrained and unrestrained women.

The objective of this investigation was to compare the acute effects of exercise and diet manipulations on energy intake, between dietary restrained and unrestrained females. Comparisons of two studies using an identical 2 x 2 repeated-measures design (level of activity (rest or exercise) and lunch type (high-fat or low-fat)) including thirteen dietary unrestrained and twelve restrained females were performed. Energy expenditure during the rest session was estimated and the energy cost of exercise was measured by indirect calorimetry. Relative energy intake was calculated by subtracting the energy expenditure of the exercise session from the energy intake of the test meal. Post-meal hedonic ratings were completed after lunch. Energy intake and relative energy intake increased during high-fat conditions compared with the low-fat, independently of exercise (P < 0.001). There was a positive relationship between dietary restraint scores and energy intake or relative energy intake in the rest conditions only (r 0.54, P < 0.01). The decrease of relative energy intake between the rest and exercise conditions was higher in restrained than in unrestrained eaters (P < 0.01). These results confirm that a high-fat diet reversed the energy deficit due to exercise. There was no energy compensation in response to an acute bout of exercise during the following meal. In restrained eaters, exercise was more effective in creating an energy deficit than in unrestrained eaters. Exercise may help restrained eaters to maintain control over appetite.

Adult↗
PubMed1999

Effects of sweetness and energy in drinks on food intake following exercise.

Exercise is known to cause physiological changes that could affect the impact of nutrients on appetite control. This study was designed to assess the effect of drinks containing either sucrose or high-intensity sweeteners on food intake following exercise. Using a repeated-measures design, three drink conditions were employed: plain water (W), a low-energy drink sweetened with artificial sweeteners aspartame and acesulfame-K (L), and a high-energy, sucrose-sweetened drink (H). Following a period of challenging exercise (70% VO2 max for 50 min), subjects consumed freely from a particular drink before being offered a test meal at which energy and nutrient intakes were measured. The degree of pleasantness (palatability) of the drinks was also measured before and after exercise. At the test meal, energy intake following the artificially sweetened (L) drink was significantly greater than after water and the sucrose (H) drinks (p < 0.05). Compared with the artificially sweetened (L) drink, the high-energy (H) drink suppressed intake by approximately the energy contained in the drink itself. However, there was no difference between the water (W) and the sucrose (H) drink on test meal energy intake. When the net effects were compared (i.e., drink + test meal energy intake), total energy intake was significantly lower after the water (W) drink compared with the two sweet (L and H) drinks. The exercise period brought about changes in the perceived pleasantness of the water, but had no effect on either of the sweet drinks. The remarkably precise energy compensation demonstrated after the higher energy sucrose drink suggests that exercise may prime the system to respond sensitively to nutritional manipulations. The results may also have implications for the effect on short-term appetite control of different types of drinks used to quench thirst during and after exercise.

Adult↗
PubMed1999

What processes are involved in the appetite response to moderate increases in exercise-induced energy expenditure?

It is intuitive that an energy deficit induced by exercise induces an automatic increased drive for food (hunger and energy intake). However, the absence of a compensatory increase in energy intake (EI) in response to an exercise-induced increase in energy expenditure (EE) is now well documented. Thus, there is a weak coupling between exercise-induced increases in EE and EI. One paradox related to the phenomenon of a weak coupling between the exercise-induced EE and EI is the observation of a positive relationship between physical activity and food intake in the long-term free-living situation (i.e. tight coupling between EE and EI). It is possible, therefore, that a period of transition (uncoupling) occurs in the short-term, before a steady-state (coupling) condition is achieved. It is likely that a combination of physiological and behavioural adaptations occur in order to achieve a tight coupling between EE and EI. The precise physiological and behavioural changes that take place to obtain a new equilibrium (i.e. coupling between EE and EI) are still undetermined. The expectation that exercise-induced increases in EE should drive up hunger and food intake tends to be based on the concept of a strong coupling between physiology and behaviour. However, because of the individual's strong volitional control over eating behaviour, the psychological influences on the appetite response to exercise should not be undervalued. The psychological position of the individual (e.g. dietary restraint, food-related cognitions, reasons for exercising) could have a very strong influence on the food intake response to exercise. Misjudgements concerning the energy value of the food (EI) relative to the energy value of the exercise (EE) could be one possibility why exercise fails to be a successful method of weight loss for some individuals.

Appetite↗
PubMed1999

Physical activity and regulation of food intake: current evidence.

OBJECTIVE: The evidence was reviewed on how physical activity could influence the regulation of food intake by either adjusting the sensitivity of appetite control mechanisms or by generating an energy deficit that could adjust the drive to eat. DESIGN: Interventionist and correlational studies that had a significant influence on the relationship between physical activity and food intake were reviewed. Interventionist studies involve a deliberate imposition of physical activity with subsequent monitoring of the eating response. Correlational studies make use of naturally occurring differences in the levels of physical activity (between and within subjects) with simultaneous assessment of energy expenditure and intake. SUBJECTS: Studies using lean, overweight, and obese men and women were included. RESULTS: Only 19% of interventionist studies report an increase in energy intake after exercise; 65% show no change and 16% show a decrease in appetite. Of the correlational studies, approximately half show no relationship between energy expenditure and intake. These data indicate a rather loose coupling between energy expenditure and intake. A common sense view is that exercise is futile as a form of weight control because the energy deficit drives a compensatory increase in food intake. However, evidence shows that this is not generally true. One positive aspect of this is that raising energy expenditure through physical activity (or maintaining an active life style) can cause weight loss or prevent weight gain. A negative feature is that when people become sedentary after a period of high activity, food intake is not "down-regulated" to balance a reduced energy expenditure. CONCLUSION: Evidence suggests that a high level of physical activity can aid weight control either by improving the matching of food intake to energy expenditure (regulation) or by raising expenditure so that it is difficult for people to eat themselves into a positive energy balance.

Anorexia↗
PubMed1998

No evidence for linkage of the CHRNA7 gene region in Canadian schizophrenia families.

Schizophrenia patients demonstrate a deficiency in the filtering of sensory information, and one specific measure involves a response to the second of a pair of auditory stimuli. A neurophysiological measure of this consists of the electroencephalographic response to pairs of auditory signals, emitted fractions of a second apart. Schizophrenic patients and some of their unaffected relatives show a failure of inhibition of a second tone if it occurs 50 msec after the first. A recent genome scan indicated that the gating defect is linked to the alpha 7 neuronal nicotinic acetyl choline receptor gene on chromosome 15. We genotyped 5 schizophrenia families with a total of 96 subjects with a dinucleotide polymorphic marker located less than 120 kb from the first exon of the alpha 7 neuronal nicotinic acetylcholine receptor gene. Linkage analysis was undertaken using parametric and nonparametric statistical methods. The results of the parametric analysis showed negative lod scores under both narrow and broad diagnosis (lod = -3.6 and -4.8, respectively, at theta = 0), and dominant and recessive modes of transmission of the disease. Nonparametric analysis using GENEHUNTER produced nonsignificant NPL scores (NPL = -0.4 and -0.3 for broad and narrow diagnoses, respectively). In summary, we did not find any evidence that the alpha 7 neuronal nicotinic acetylcholine receptor gene (CHRNA7) is linked to schizophrenia. However, we have not been able to assess the P50 measures in these families.

Chromosomes, Human, Pair 15↗
PubMed1998

Uncoupling the effects of energy expenditure and energy intake: appetite response to short-term energy deficit induced by meal omission and physical activity.

The effects of two methods of inducing an acute energy deficit (exercise and a low-energy breakfast) on appetite were investigated in 11 healthy females, all of whom were regular exercisers and regular breakfast eaters. There were four experimental days: with exercise and a high-energy (500 kcal) breakfast (EHB), exercise and a low-energy (64 kcal) breakfast (ELB), no exercise and a high-energy breakfast (NEHB) and no exercise and a low-energy breakfast (NELB). Hunger and moods were monitored each hour from 8 a. m. until 5 p.m. Energy and macronutrient intake were measured during an ad libitum lunch test meal 4 h after the exercise and breakfast. Heart rate was continuously monitored using the Polar sport tester. The low-energy breakfasts (ELB and NELB) led to increased hunger during the morning and an increase in energy intake at lunch compared with the high-energy breakfasts. Subjects also experienced significantly more food cravings after LBs than after HBs. Exercise failed to have any significant effect on these variables. Thus, two methods of inducing a short-term energy deficit had markedly different effects on appetite. The low-energy breakfast presumably fails to generate the inhibitory satiety signals induced by the 500 kcal breakfast, whereas the metabolic effects of an exercise session failed to generate excitatory signals to hunger and food intake.

Adult↗
PubMed1998

Exercise in dietary restrained women: no effect on energy intake but change in hedonic ratings.

OBJECTIVES: To investigate the short-term effects (one day) of exercise and diet composition on appetite control in restrained females. DESIGN: 2x2 repeated measures design, with exercise and lunch type used as the repeated factors. SETTING: The Human Appetite Research Unit at Leeds University Psychology Department. SUBJECTS: Twelve dietary restrained females, normal weight and regular exercisers INTERVENTIONS: A control (rest) and a bout of high intensity exercise (cycling 50 min., 70% VO2 max.) was followed by a free-selection lunch comprising high-fat (HF) or low-fat (LF) foods. Hunger and heart rate profiles were tracked. Energy Intake (EI) was monitored in the laboratory throughout the day. Post-meal hedonic ratings were completed after lunch and dinner. RESULTS: There was a significant effect of lunch type (HF vs LF) on EI following exercise and rest (P < 0.001) and on total 24 h EI (P < 0.05): EI increased during both HF conditions compared to the LF. A main effect of exercise on tastiness and pleasantness (P < 0.05) of the LF foods served at lunch was found. However, there was no effect of exercise on hunger, weight or energy value of food eaten. CONCLUSIONS: Exercise raises the perceived pleasantness of foods in dietary restrained women, but does not increase the drive to eat within 8 h of the cessation of exercise. The combination of physical activity and a low-fat diet could be used advantageously to control appetite, prevent overconsumption and protect against the development of obesity.

Adult↗
PubMed1998

Effects of exercise on appetite control: loose coupling between energy expenditure and energy intake.

The relationship between physical activity and energy intake (food consumption) can take a number of forms, depending on the intensity, duration and frequency of the activity, and upon the degrees of fitness and physiological status of the individual. At extremes of energy expenditure such as those found in long distance cyclists, voluntary energy intake may be sufficient to balance the enormous daily expenditure; this is due to an entraining effect. Under more normal situations, there is a widely held belief that physical activity is a poor strategy for losing weight, since the energy expended drives up hunger and food intake to compensate for the energy deficit incurred. Recent studies in both normal weight and obese individuals show that substantial periods of exercise do not increase hunger and do not drive up food intake. Comparisons between sedentary and normally active individuals, or between enforced periods of rest or strenuous activity, generate little or no effect on levels of hunger or daily energy intake, indicating a rather loose physiological coupling between energy expenditure and food intake. This view generates an optimistic view of the role of exercise in weight loss and weight control, as it indicates that intake is not automatically driven up to compensate for energy expended. Reasons why physical activity often produces disappointing effects, rise from inappropriate food choices, a desire for self-reward after exercise and misjudgements about the relative rates at which energy can be expended (by exercise) or taken in (by eating). This means that physical activity will be most beneficial for weight control, if carried out in conjunction with a low energy dense diet or with judicious control of eating.

Appetite↗
PubMed1997

High dose exercise does not increase hunger or energy intake in free living males.

OBJECTIVE: To examine the effects of a high dose (two high-intensity exercise sessions) of exercise on energy intake (EI) and subjective states (hunger and mood). DESIGN: Using a within subjects design, there were two treatment conditions, each of two consecutive days. SETTING: The Human Appetite Research Unit at Leeds University Psychology Department. SUBJECTS: Eight lean males who were regular exercisers were recruited from the student/staff population of Leeds University. INTERVENTIONS: The effects of the high dose of exercise Ex1 were compared with the effects on the day immediately after exercise (Ex2) and two consecutive days of no exercise (R1 and R2). EI was monitored using self-record food diaries and subjective states were tracked using a new Electronic Appetite Rating System (EARS). Heart rate and physical activity were also measured. RESULTS: Feelings of hunger were not elevated by the high dose of exercise on Ex1 or on the day after exercise (Ex2). In fact, average daily feeling of hunger on Ex1 was significantly lower compared with the average daily feeling of hunger on Ex2 (t = 3.15, d.f. = 7, P < 0.05), but not when compared with R1 or R2. EI and macronutrient intakes were not different on Ex1, Ex2, R1 or R2. Therefore, there were no increase in EI on Ex1 or Ex2 to account for the measured increase in exercise-induced energy expenditure (1200 kcal). Continuously monitored heart rate and activity profiles indicated that there was no difference in activity during the non-exercise periods between the four days. CONCLUSIONS: This study indicates that a high dose of exercise in one day failed to have any effect on EI within the same day or on the day immediately after exercise, compared with days of no exercise. These results demonstrate that an acute but substantial increase in energy expenditure (EE) due to intense exercise does not automatically increase hunger or EI within 48 h. This indicates the absence of any strong coupling between EE and EI in the short-term, probably as a result of food intake being held in place by environmental contingencies and short-term pre-absorptive physiological responses arising from eating itself.

Adult↗
PubMed1997

Effects of exercise on appetite control: implications for energy balance.

At a time of increased obesity, decreased physical activity, and high food consumption, the relationship between physical activity and appetite control needs to be examined. Many people believe that the energy expended as a result of physical activity generates a drive to eat. However, a counterintuitive conclusion arises since there is no compelling evidence that increased physical activity increases energy intake. A suppression of hunger occurs following intense exercise; however, this effect is brief and has no influence on energy intake. Indeed, there does not appear to be any within-day effect of exercise on energy intake. Day-to-day effects of exercise on energy intake could occur, but only a few provocative data exist showing a delayed effect of exercise on energy intake 2 d later. Therefore, there appears to be only a weak short-term coupling between energy expenditure and energy intake. What about the effects of increased physical activity on food selection? The natural hypothesis would be that the energy reserves used during exercise would estimate a drive for a particular nutrient. There is no clear consistent evidence to indicate that in the short-term, exercise induces changes in food or nutrient preferences. In the long-term there is some evidence that physical activity is associated with an increase in carbohydrate intake, but it is uncertain whether these changes are biologically driven for a result of changes of a psychological nature. Contrary to a popularly held view, food selection and nutrient intake constitute patterns of behavior held in place by environmental contingencies and short-acting post-ingestive physiological responses; these patterns of behavior are relatively immune to modulation by the metabolic effects of exercise.

Appetite Regulation↗
PubMed1996

Overconsumption as a cause of weight gain: behavioural-physiological interactions in the control of food intake (appetite).

There is an asymmetry in the operation of physiological processes that maintain body weight. The body exerts a strong defence against undernutrition and weight loss, but applies a much weaker resistance to overconsumption and weight gain. These principles influence how appetite control operates and this constitutes one form of vulnerability to weight gain. The expression of appetite is reflected in an episodic pattern of eating behaviour, the selection of dietary commodities and an associated profile of conscious sensations such as hunger, preferences, aversions and fullness. The onset and termination of eating episodes are subject to facilitatory and inhibitory physiological processes, and are held in place by strong environmental contingencies and habitual routines. Energy intake resulting from physiological and environmental control of behaviour is generally in balance with energy expenditure, although changes in energy expenditure do not inevitably trigger changes in food intake. Excess energy intake over expenditure may be due to aberrant positive drive to seek energy or a permissive response to strong external stimuli. The former could arise from a defect in a lipostatic regulatory system, and the latter from the weakness of inhibitory signals or from strong facilitatory responses to superpotent physical features of food. Taste and textural qualities of food give rise to hedonic responses via opioidergic and aminergic systems. Inhibitory responses to macronutrients include adjustment of gastric volume, rate of gastric emptying, release of cholecystokinin and enterostatin, and changes in plasma levels of products of digestion. These peripheral responses lead to a series of changes in brain neurotransmitter networks. Proteins, fats and carbohydrates generate different sets of physiological responses that produce different effects on the intensity and duration of satiety. The nutrient composition of food and the overall energy density influence control of meal size and post-ingestive inhibition. Particular sensory and nutrient combinations in foods can facilitate passive overconsumption. Overriding physiological satiety signals can lead to a positive energy balance and weight gain.

Animals↗