Marion M. Hetherington

An obesity-associated FTO gene variant and increased energy intake in children

BACKGROUND Variation in the fat mass and obesity-associated (FTO) gene has provided the most robust associations with common obesity to date. However, the role of FTO variants in modulating specific components of energy balance is unknown. METHODS We studied 2726 Scottish children, 4 to 10 years of age, who underwent genotyping for FTO variant rs9939609 and were measured for height and weight. A subsample of 97 children was examined for possible association of the FTO variant with adiposity, energy expenditure, and food intake. RESULTS In the total study group and the subsample, the A allele of rs9939609 was associated with increased weight (P=0.003 and P=0.049, respectively) and body-mass index (P=0.003 and P=0.03, respectively). In the intensively phenotyped subsample, the A allele was also associated with increased fat mass (P=0.01) but not with lean mass. Although total and resting energy expenditures were increased in children with the A allele (P=0.009 and P=0.03, respectively), resting energy expenditure was identical to that predicted for the age and weight of the child, indicating that there is no defect in metabolic adaptation to obesity in persons bearing the risk-associated allele. The A allele was associated with increased energy intake (P=0.006) independently of body weight. In contrast, the weight of food ingested by children who had the allele was similar to that in children who did not have the allele (P=0.82). CONCLUSIONS The FTO variant that confers a predisposition to obesity does not appear to be involved in the regulation of energy expenditure but may have a role in the control of food intake and food choice, suggesting a link to a hyperphagic phenotype or a preference for energy-dense foods.

The specificity of satiety: The influence of foods of different macronutrient content on the development of satiety

The effects of consuming equicaloric preloads with different macronutrient contents on the development of satiety were investigated. Ten normal-weight, nondieting women fasted overnight and then rated hunger, fullness, and food preferences, and the pleasantness of the taste of food samples before and after five different preloads. The greatest changes in the pleasantness of the taste of the food occurred for the eaten food relative to the uneaten food. Macronutrient content of the preloads did not significantly influence the magnitude of these changes or the pleasantness of foods with similar nutrient contents. Therefore, no evidence of nutrient-specificity was obtained. Nutrient composition had a differential effect on hunger, fullness and food intake. Ratings of hunger decreased and fullness increased following the high starch and high protein preloads to a greater extent than after the high fat, high sucrose and mixed content preloads. When a self-selection meal was offered 2 hours after the preloads energy intake and preference for high carbohydrate and high fat food items were significantly decreased by the high protein and high starch preloads. However, no specific reduction in macronutrient intake was observed. In conclusion, differential effects of the preloads were observed in subjective ratings of hunger, fullness, preferences and subsequent food intake, but there was no indication that satiety was macronutrient-specific.

Situational effects on meal intake: A comparison of eating alone and eating with others

Eating in competition with other tasks has been shown to increase food intake, particularly when tasks are cognitively demanding. To test the hypothesis that social facilitation of eating occurs, in part, as a function of distraction which impairs the ability to self-monitor, eating with others was compared with eating alone or in front of the television. Using a repeated measure within-subjects design, thirty-seven participants (21 males) visited the laboratory 4 times to eat a buffet-style lunch ad libitum. All eating episodes were filmed. Energy intake (EI) was measured when participants ate alone (A), ate alone while watching TV (B), ate with two same sex strangers (C), and ate with two same sex friends (D) in a counterbalanced order. EI was significantly enhanced by presence of familiar others (D: 4565+/-272 kJ, p < 0.001) and watching TV (B: 4350+/-252 kJ, p < 0.05) compared to baseline (A: 3861+/-200 kJ). Length of eating episode correlated significantly (p < 0.05) with EI, however, amount of time spent eating and looking at food differed by condition with a greater percentage of time focussed on food during baseline (p < 0.001). Eating with friends increased EI by 18% and eating in front of the TV increased EI by 14% relative to baseline. Engaging in conversation or watching TV draws attention away from the eaten food and can stimulate food intake. However, since eating with strangers also drew attention away from food but did not result in increased intake, social facilitation effects are not simply due to distraction. Thus food intake can be enhanced when attention to food and self-monitoring are impaired during distraction, however, this effect is moderated when eating with strangers.

Older adults and patients in need of nutritional support: Review of current treatment options and factors influencing nutritional intake

BACKGROUND & AIMS Many older adults and patients do not achieve sufficient nutritional intake to support their minimal needs and are at risk of, or are suffering from, (protein-energy) malnutrition. Better understanding of current treatment options and factors determining nutritional intake, may help design new strategies to solve this multifactorial problem. METHODS Medline, Science Citation Index, ScienceDirect and Google databases (until December 2008) were searched with the keywords malnutrition, elderly, older adults, food intake, energy density, variety, taste, satiety, and appetite. RESULTS 37 Factors affecting nutritional intake were identified and divided in three categories; those related to the environment, the person, and the food. For older adults in nursing homes, encouragement by carers and an appropriate ambiance seem particularly important. Meal fortification, offering variety, providing frequent small meals, snacks and particularly Oral Nutritional Supplements (ONS) between meals are other possibilities for this group. Product factors that stimulate intake include palatability, high energy density, low volume, and liquid format. CONCLUSION The current review gives a comprehensive overview of factors affecting nutritional intake and may help carers to improve nutritional intake in their patients. The product factors identified here suggest that especially small volume, energy and nutrient dense ONS can be effective to improve nutritional intake.

Stress and eating: the effects of ego-threat and cognitive demand on food intake in restrained and emotional eaters

Restrained and emotional eaters overeat in response to stress. To compare differential effects of cognitive demand and ego-threatening stressors on subsequent chocolate intake, 38 females completed a neutral (control), an ego threatening and an incongruent Stroop colour-naming task on three separate occasions. Participants were assigned to four groups based on median-split scores on the restrained and emotional eating scales of the Dutch Eating Behaviour Questionnaire-high restraint/high emotional, high restraint/low emotional, low restraint/high emotional and low restraint/low emotional. Higher response latencies were observed in the incongruent task, confirming its greater cognitive (attentional) demand. Overall intake was enhanced by 23% after ego-threat and 15% after the incongruent Stroop task relative to control. Restraint was associated with greater intake after both ego-threat and the incongruent task than in the control condition. In contrast, emotional eating was associated with greater intake after only the ego-threat, relative to control. A positive association between reaction time and subsequent intake in all conditions for high restraint/low emotional eaters provided support for the limited capacity hypothesis. Enhanced intake in emotional eaters is proposed to relate to escape from self-awareness. These findings demonstrate differential effects of threat and demand on stress-related eating in restrained and emotional eaters.

Set points, settling points and some alternative models: Theoretical options to understand how genes and environments combine to regulate body adiposity

The close correspondence between energy intake and expenditure over prolonged time periods, coupled with an apparent protection of the level of body adiposity in the face of perturbations of energy balance, has led to the idea that body fatness is regulated via mechanisms that control intake and energy expenditure. Two models have dominated the discussion of how this regulation might take place. The set point model is rooted in physiology, genetics and molecular biology, and suggests that there is an active feedback mechanism linking adipose tissue (stored energy) to intake and expenditure via a set point, presumably encoded in the brain. This model is consistent with many of the biological aspects of energy balance, but struggles to explain the many significant environmental and social influences on obesity, food intake and physical activity. More importantly, the set point model does not effectively explain the ‘obesity epidemic’ – the large increase in body weight and adiposity of a large proportion of individuals in many countries since the 1980s. An alternative model, called the settling point model, is based on the idea that there is passive feedback between the size of the body stores and aspects of expenditure. This model accommodates many of the social and environmental characteristics of energy balance, but struggles to explain some of the biological and genetic aspects. The shortcomings of these two models reflect their failure to address the gene-by-environment interactions that dominate the regulation of body weight. We discuss two additional models – the general intake model and the dual intervention point model – that address this issue and might offer better ways to understand how body fatness is controlled.

Appetite sensations and satiety quotient: predictors of energy intake and weight loss.

PURPOSE The aim of this study was to further evaluate the validity and clinical meaningfulness of appetite sensations to predict overall energy intake as well as body weight loss. METHODS Men (n = 176) and women (n = 139) involved in six weight loss studies were selected to participate in this study. Visual analogue scales were used to measure appetite sensations before and after a fixed test meal. Fasting appetite sensations, 1 h post-prandial area under the curve (AUC) and the satiety quotient (SQ) were used as predictors of energy intake and body weight loss. Two separate measures of energy intake were used: a buffet style ad libitum test lunch and a three-day self-report dietary record. RESULTS One-hour post-prandial AUC for all appetite sensations represented the strongest predictors of ad libitum test lunch energy intake (p < or = 0.001). These associations were more consistent and pronounced for women than men. Only SQ for fullness was associated with ad libitum test lunch energy intake in women. Similar but weaker relationships were found between appetite sensations and the 3-day self-reported energy intake. Weight loss was associated with changes in appetite sensations (p < or = 0.01) and the best predictors of body weight loss were fasting desire to eat; hunger; and PFC (p < or = 0.01). CONCLUSIONS These results demonstrate that appetite sensations are relatively useful predictors of spontaneous energy intake, free-living total energy intake and body weight loss. They also confirm that SQ for fullness predicts energy intake, at least in women.

Old and alone: barriers to healthy eating in older men living on their own

Ageing is associated with reduced energy intake and loss of appetite. Older men tend to have poorer dietary intakes including consumption of fewer fruits and vegetables in comparison to older women. Living and eating alone further diminishes food consumption and dietary quality. The aim of the present study was to explore food choice and energy intake in older men living alone using both quantitative and qualitative methods. 39 older men were interviewed and completed questionnaires on health, food choice, dietary patterns and appetite. Few men managed to consume recommended levels of energy, essential trace elements or vitamins A and D. Age and BMI failed to predict patterns of intake, but men with good cooking skills reported better physical health and higher intake of vegetables. However, cooking skills were negatively correlated with energy intake. Men who managed to consume at least 4 portions of fruits and vegetables each day had significantly higher vitamin C levels, a greater percentage of energy as protein and generally more adequate diets. Interviews revealed that poor cooking skills and low motivation to change eating habits may constitute barriers to improving energy intake, healthy eating and appetite in older men (193).

The time course of sensory-specific satiety

The time course of the changes in hedonic response following ingestion of three different foods was investigated. Normal weight, non-dieting female subjects rated the pleasantness of the appearance, smell, texture and taste of nine foods and then consumed as much as they wanted of cheese on cracker, tomato soup or orange jello. After this first course, subjects re-rated the pleasantness of the foods at 2, 20, 40 and 60 min. Following the 60 min rating, subjects were offered a second course of cheese on cracker or chocolate bar. For all sensory variables measured and for all foods consumed, the greatest decline in pleasantness occurred for the eaten food 2 min after consumption. For the food rate as most palatable (cheese on cracker) there was some recovery of pleasantness of the texture and taste over the hour. Intake in the second course was similar regardless of whether the food offered was different or the same as the food consumed in the first course. Since changes in the pleasantness of the foods occurred rapidly for all sensory variables studied and since the magnitude of these changes did not increase over time, it is concluded that the development of sensory-specific satiety is related primarily to the sensory stimulation accompanying ingestion as opposed to the postabsorptive effects of consuming these foods.

Stimulus satiation: effects of repeated exposure to foods on pleasantness and intake.

Frequent and repeated exposure to foods produces stimulus satiation or monotony. To explore further the nature of stimulus satiation, two experiments were conducted. Experiment 1 investigated the influence of initial pleasantness and frequency of intake on monotony. Tests showed that bread and butter was eaten more frequently but was liked less than chocolate. Therefore, normal-weight, healthy males were randomly assigned to either a chocolate condition (CC, N=13) or bread and butter condition (BC, N=16). All subjects received fixed amounts of the assigned food (67g/1473kJ of chocolate or 95g/1355kJ of bread and butter) every day for 22 days. On days 1, 8, 15 and 22 subjects consumed this food ad libitum. Pleasantness of taste and desire to eat chocolate declined significantly over time but no such changes were observed for bread and butter. Experiment 2 examined intake, pleasantness and desire to eat chocolate in 53 subjects over a 15 day period, with 3 conditions: control (CS: N=15), fixed (FS: N=20) and variable (VS: N=18). CS received no chocolate except on test days (days 1, 8 and 15), FS received 67g/1473kJ of chocolate daily and VS received increasing amounts of chocolate from 57g/1251kJ on day 1 to 86g/1888kJ by day 12. Pleasantness and desire to eat chocolate declined over time with this being more pronounced for F and V subjects. However, ad libitum intake increased over time. Both experiments demonstrated significant changes in pleasantness and desire to eat chocolate, but no commensurate decline in intake. Thus, although stimulus satiation occurred for subjective ratings of pleasantness and desire to eat chocolate, intake remained unaffected. This apparent dissociation between pleasantness and intake may reflect different processes underlying liking and wanting.