john blundell

Hunger, appetite, satiety, and energy intake (EI) are controlled by both physiological and psychological cues, many of which are learned in specific environmental contexts. Appetite is not tightly regulated but has evolved to protect humans and other mammals from energy deficits in uncertain environments and so it is relatively easy to overeat in modern affluent environments. Numerous factors influence EI including sensory perceptions, emotional state, reward-based responses to food, social and situational influences, dietary energy density, and composition. There are few clearly defined differences in determinants of appetite and EI in people with different levels of body fat, because the pathways to and from obesity are multiple and heterogeneous.

Any explanation of appetite control should contain a description of physiological processes that could contribute a drive to eat alongside those that inhibit eating. However, such an undertaking was largely neglected until 15 years ago when a series of independent research programmes investigated the physiological roles of body composition and appetite. These outcomes demonstrated that fat-free mass (FFM), but not fat mass, was positively associated with objectively measured meal size and energy intake (EI). These findings have been accompanied by demonstrations that resting metabolic rate (RMR) is also positively associated with EI, with the influence of FFM largely mediated by RMR. These findings re-introduce the role of drive into models of appetite control and indicate how this can be integrated with processes of inhibition. The determinants of EI fit into an evolutionary perspective in which the energy …

Over several decades, the health benefits of consuming nuts have been investigated, resulting in a large body of evidence that nuts can reduce the risk of chronic diseases. The consumption of nuts, being a higher-fat plant food, is restricted by some in order to minimize weight gain. In this review, we discuss several factors related to energy intake from nuts, including food matrix and its impact on digestibility, and the role of nuts in regulating appetite. We review the data from randomized controlled trials and observational studies conducted to examine the relationship between nut intake and body weight or body mass index. Consistently, the evidence from RCTs and observational cohorts indicates that higher nut consumption does not cause greater weight gain; rather, nuts may be beneficial for weight control and prevention of long-term weight gain. Multiple mechanisms likely contribute to these findings, including aspects of nut composition which affect nutrient and energy availability as well as satiety signaling.

These recent findings suggest that fat-free mass and resting metabolic rate are determinants of energy intake. Consideration of fat-free mass and energy expenditure as physiological sources of appetitive signals helps reconcile the mechanisms underpinning the inhibition of eating with those that drive eating.

There has been no validated digital tool for measuring appetite with a visual analog scale (VAS) through a mobile app using participants’ smart phones for data collection in virtual settings. To fill the gap, we developed a digital VAS and conducted a digital cross-over clinical trial by comparing appetite responses measured by this digital tool versus paper-based VAS in 102 participants in a free-living environment. Participants consumed either a 230 or 460 kcal breakfast in randomized order in two virtual sessions, and their appetite was measured over the next 4 h using both tools. The results revealed no significant difference in hunger, fullness, satiety, or desire to eat measured by digital and paper VAS. Paper VAS resulted in a higher prospective consumption score than digital VAS; the difference (1.1 out of 100 points) was statistically significant but not practically relevant. Bland and Altman analysis also indicated consistency in the results from the two methods. In conclusion, digital VAS on a smart phone is a validated tool for appetite measurement in the real world; it provides a new way for researchers to leverage participants’ mobile devices for appetite data collection in digital trials.

From a public health perspective, much of the interest in the relationship between exercise and appetite rests on the implications for energy balance and obesity. Energy balance reflects a dynamic 2-way interaction between energy expenditure (EE) and energy intake (EI). Physical activity and exercise, and appetite are the behavioural components of EE and EI, respectively. Beyond EE, exercise is a powerful and complex physiological stimulus acting on several bodily systems. There are multiple effects of frequent and prolonged exercise on appetite which include inter alia an increase in fasting hunger, an enhancement of post-prandial satiety, a modulation of the hedonic responses to food and improvements in eating behaviour traits. These lead to variable adjustments in EI and in a reduction in the susceptibility to overconsumption. Frequent and prolonged physical activity and exercise behaviour can strengthen …

Over several decades, the health benefits of consuming nuts have been investigated, resulting in a large body of evidence that nuts can reduce the risk of chronic diseases. The consumption of nuts, being a higher-fat plant food, is restricted by some in order to minimize weight gain. In this review, we discuss several factors related to energy intake from nuts, including food matrix and its impact on digestibility, and the role of nuts in regulating appetite. We review the data from randomized controlled trials and observational studies conducted to examine the relationship between nut intake and body weight or body mass index. Consistently, the evidence from RCTs and observational cohorts indicates that higher nut consumption does not cause greater weight gain; rather, nuts may be beneficial for weight control and prevention of long-term weight gain. Multiple mechanisms likely contribute to these findings, including aspects of nut composition which affect nutrient and energy availability as well as satiety signaling.

This secondary analysis examined the influence of changes in physical activity (PA), sedentary time and energy expenditure (EE) during dietary energy restriction on the rate of weight loss (WL) and 1-year follow-up weight change in women with overweight/obesity. Measurements of body weight and composition (air displacement plethysmography), RMR (indirect calorimetry), total daily EE (TDEE) and activity EE (AEE), minutes of PA and sedentary time (PA monitor) were taken at baseline, after 2 weeks, after ≥5 % WL or 12 weeks of continuous (25 % daily energy deficit) or intermittent (75 % daily energy deficit alternated with ad libitum day) energy restriction, and at 1-year post-WL. The rate of WL was calculated as total %WL/number of dieting weeks. Data from both groups were combined for analyses. Thirty-seven participants (aged 35 (sd 10) years; BMI = 29·1 (sd 2·3) kg/m2) completed the intervention (WL …

Appetite control is influenced by biological, nutritional, physical, and social factors which interact to form a complex system. Appetite cannot be considered as a single entity that can be reduced to a simple cause and effect process. A key feature of humans is that they are omnivores and have the potential to make choices from a huge variety of foods. This is both an asset and a liability. Appetite can be broadly divided into the drive to eat and food choice behavior. The experienced pleasure of eating (hedonics) is a major influence on food choice. Foods chosen bring about an inhibition to the drive to eat through the processes of satiation and satiety. Satiety is the post-prandial inhibitory component of appetite control. There is huge individual variability in the way people experience satiety. The strength of satiety is heavily influenced by the diet selected. In modern technological societies, components of diets have important effects on appetite control.

Positive associations between fat-free mass (FFM) and hunger have been previously observed, but it remains unknown how specific organs influence hunger. This exploratory study examined if the between-subject variance in fasting hunger was better explained when FFM was assessed at the tissue-organ level than as a uniform body component. Whole-body (quantitative magnetic resonance) and tissue-organ body composition (magnetic resonance imaging; MRI), resting metabolic rate (RMR; indirect calorimetry) and fasting hunger (100-mm visual analogue scale) were assessed in 24 healthy men (age= 25±3y; BMI= 23.5±2.1 kg/m2). Spearman correlations were conducted with Bonferroni corrections. FFM (rs= 0.44; p= 0.03) and RMR (rs= 0.44; p= 0.04), but not fat mass (rs= 0.05; p= 0.82), were positively associated with fasting hunger. The association between combined high-metabolic rate organ masses …

Food texture seems to offer a promising strategy for the control of expected satiety, satiety, satiation and daily caloric intake. The aim of this study was to examine the effect of food texture, more specifically the effect of different levels of viscosity, on perceived satiety through an online survey where the viscosity levels of protein-based beverages were visually perceived using a newly developed video-based demonstration. Whey protein beverages were prepared with viscosities being manipulated using xanthan gum and their viscosity and tribological properties were measured instrumentally. Subjects (n = 211) watched beverages being poured in videos streamed online and were instructed to imagine drinking them. The results showed that instrumentally measured HV (high viscous) and MV (medium viscous) beverages were visually perceived by the participants as being more satiating immediately and 2 h later …

Reward for high-energy food is often associated with obesity. Whether liking (L) and implicit wanting (IW) for low or high-fat food can distinguish between individuals with or without obesity remains unknown. Therefore, 92 women (n= 46 lean, n= 46 with overweight/obesity) were recruited. The Leeds Food Preference Questionnaire was used to assess L & IW for high-fat-savoury (HFSA), low-fat-savoury (LFSA), high-fat-sweet (HFSW) and low-fat-sweet (LFSW) after an overnight fast, pre-and post-lunch. Appetite control measures included food intake, eating behaviour traits (TFEQ, BES, CoEQ) and body composition (BodPod). Independent t-tests and Spearman correlations were performed. Women with obesity had higher binge eating, disinhibition, and lower craving control than lean women, but no differences in cravings or food intake. Only fasted IW for LFSW differed between groups (p=. 046, d=. 42) and was …

BackgroundFat-free mass (FFM) has been shown to be positively associated with hunger and energy intake, an association mediated by resting metabolic rate (RMR). However, FFM comprises a heterogeneous group of tissues with distinct metabolic rates, and it remains unknown how specific high-metabolic rate organs contribute to the degree of perceived hunger.ObjectiveTo examine whether FFM and its anatomical components were associated with fasting hunger when assessed at the tissue-organ level.DesignBody composition (quantitative magnetic resonance and magnetic resonance imaging), RMR and whole-body glucose oxidation (indirect calorimetry), HOMA-index as a marker of insulin sensitivity, nitrogen balance and fasting hunger (visual analogue scales) were assessed in 21 healthy males (age = 25 ± 3y; BMI = 23.4 ± 2.1 kg/m2) after 3 days of controlled energy balance.ResultsFFM (rs = 0.39; p …

Keywords Video recording, expected satiety, food texture, rheology Food texture seems to offer a promising strategy for the control of expected satiety, satiety, satiation and daily caloric intake. The aim of this study was to examine the effect of food texture, more specifically the effect of different levels of viscosity, on perceived satiety through an online survey where the viscosity levels of protein-based beverages were visually perceived using a newly developed video-based demonstration. Whey protein beverages were prepared with viscosities being manipulated using xanthan gum and their viscosity and tribological properties were measured instrumentally. Subjects (n= 211) watched beverages being poured in videos streamed online and were instructed to imagine drinking them. The results showed that instrumentally measured HV (high viscous) and MV (medium viscous) beverages were visually perceived by the participants as being more satiating immediately and 2 h later after the imagined drinking event as compared to LV (low viscous) beverages (p< 0.05). Also, sensory attributes such as visually perceived smoothness, thickness, creaminess and watery were shown to be important factors in the perception of satiety (the creamier or thicker the beverage the higher the perceived satiety scores). Therefore, a video-based online demonstration is a highly feasible and convenient tool to measure the effect of food texture on perceived/expected satiety that can be useful in Covid-19 pandemic situation, latter necessitates online participation in many situations. More importantly, key role of food/beverage texture expressed through visual cues …

BackgroundUp to 30% of community-based older adults report reduced appetite and energy intake (EI), but previous research examining the underlying physiological mechanisms has focused on the mechanisms that suppress eating rather than the hunger drive and EI.ObjectivesWe examined the associations between fat-free mass (FFM), physical activity (PA), total daily energy expenditure (TDEE), and self-reported EI in older adults.MethodsThe present study was a secondary analysis of the Interactive Diet and Activity Tracking in AARP study. Body composition (deuterium dilution), PA (accelerometry), and TDEE (doubly labeled water) were measured in 590 older adults (age, 63.1 ± 5.9 years; BMI, 28.1 ± 4.9 kg/m2). The total daily EI was estimated from a single 24-hour dietary recall (EIsingle; ±1 month of PA and TDEE measurement) and the mean of up to 6 recalls over a 12-month period (EImean), with …

Raw data for all figures and tables in the associated paper 'Viscosity of food influences perceived satiety: a video based online survey'.

In this chapter, the authors present a broad view of the current background to the obesity pandemic and the importance of eating behavior. By examining differences in factors known to affect appetite regulation in individuals identified as “resistant” or “susceptible” to weight gain, they show how appetite processes mediate the relationship between differences in an individual's biology, physiology, and psychology and their eating behavior, and their response to (variations in) the environment. One approach to characterizing individual susceptibility is through the identification and characterization of phenotypes. Under controlled laboratory conditions, appetite sensations have been shown to be a valid and reliable method for measuring subjective motivation to eat and have been found to be associated with measured energy intake. However, not everyone reports a good relationship …

Addressing obesity issues by enhancing satiety in food to reduce energy intake has been acknowledged as a promising strategy and often textural interventions have been used to generate satiety. The aim of this work was to investigate if food texture expressed through preloads varying in their lubricating properties would influence appetite, subsequent food intake, salivary biomarkers and friction coefficient of the human saliva. In case study 1, the preloads were non-calorific hydrogels (high lubricating, low lubricating and control-water), n= 17. In case study 2, whey protein beverages (high, medium, low lubricating and control-water) were used as pre-loads, n= 37. Results of case study 1 showed that hunger decreased and fullness increased immediately and 10 min after consumption of high lubricating non-calorific hydrogels compared to control (p< 0.05), however, no effect on food intake, salivary biomarkers and …

Energy balance (EB) is often depicted as a set of kitchen scales in which the size of two quantities (energy intake [EI] and energy expenditure [EE]) determines the existence of a positive or negative EB and a gain or loss of weight. This gives rise to the slogan urging people living with obesity to “move more and eat less.” This request is perceived as an unhelpful health message and is, moreover, based on an assumption of a static EB system. In reality, EB is a complex biobehavioral system in which EI influences EE and EE modulates EI. The effect of EI on EE is represented by the thermic effect of food, but the effects of EE on EI remain underappreciated (1). The insightful study by Piaggi et al. in the current issue of Obesity (2) aimed to quantify the orexigenic effect of EE on body weight alongside its more commonly acknowledged “energy-consuming” effect. Partitioning these effects into independent pathways is a statistical rather than biological reflection of EB regulation, but this approach highlights the multiple pathways through which EE directly or indirectly influences body weight. Approaches that quantify these counteracting effects, and the factors that alter their partitioning, may provide new insight into why and when compensatory changes in EB are seen following EE perturbation. Partitioning the effects of EE on body weight between orexigenic and energy-consuming pathways is likely to be individually subtle and influenced by a range of biological (eg, age, sex, body composition, genetics) and behavioral factors (eg, diet selection, physical activity). An important question arising from Piaggi et al.’s study is how malleable this balance …

From a scientific perspective, hunger can be regarded as an identifiable conscious sensation which can be distinguished from other conscious states (e.g., pain, fear). The hunger state can be measured and is a marker of the existence of underlying biological processes. Measured hunger is functional and is normally associated with the act of eating. However, the conscious state of hunger, although driven physiologically, is not exclusively determined by biology; there is an environmental influence that can modulate its intensity and periodicity, and cultural factors that shape the appropriateness of the expression of hunger. Within a psychobiological framework, hunger can be considered as the expression of a ‘need state’ which mediates between biological requirements and environmental (nutritional) satisfaction. Our empirical studies show that hunger is clearly associated with biological signals (e.g …