Macronutrients effects on satiety and food intake in older and younger adults: A randomised controlled trial

Individual variations in eating rate and oral processing behaviours and their association with energy intake and appetite in older adults (≥ 65 years old)

Oral processing behaviours (OPBs) have been repeatedly associated with energy intake and appetite in younger adults; however, in older adults, these associations remain poorly understood. Older adults often experience ageing-related physiological decline, which can affect food oral manipulation and intake. This study investigated individual variations in OPBs and their association with energy intake and appetite in healthy older adults. Eighty-eight participants (44 males, mean age 73.7 SD 5.3 years) attended one visit after an overnight fast. A fixed-portion breakfast was provided and consumed in full, while consumption was video-recorded to quantify OPBs (chews, bites, swallows, chews per bite, bite size, eating rate, meal duration). Self-reported appetite was assessed using visual analogue scales (VAS). Meal energy intake was measured using an ad libitum lunch. A weighed food diary was used for the rest of the day to record food and drink intake. Generally, eating rate was negatively correlated with OPBs frequency and duration (p < 0.001). OPBs differed between genders and eating rate subgroups. From the postprandial self-reported appetite ratings, in faster compared to slower eaters, "prospective intake" was rated higher, indicating greater perceived appetite. Faster eating rate at the ad libitum meal was significantly and independently associated with greater energy intake (p < 0.001), when accounting for age, gender, BMI, lunch liking and pre-lunch appetite ratings. This study highlights the link between eating rate and energy intake in older adults and provides insights for future interventions, especially when energy intake needs to be increased in frail older adults.

Differences in appetite, food intake, and gastric emptying responses to protein intake by older adults varying in level of physical activity: A randomised controlled trial

Older adults are encouraged to increase their protein intake and engage in more physical activity to preserve muscle mass. However, since protein is considered the most satiating macronutrient, this advice might lead to a decrease in overall energy consumption. Physical activity is also recommended to older adults to enhance appetite, as it has been shown to help regulate appetite in younger adults, yet there is limited evidence to support this in older populations. The objective of this study was to investigate the impact of physical activity and protein on food intake, perceived appetite, and gastric emptying in older adults. Nineteen active and 19 less active older adults completed a single-blind, randomised, crossover trial involving two test days at home. Participants received a standard breakfast, followed by an isovolumetric (250 ml) and isocaloric (∼300 kcal) high- or low-protein preload milkshake (57% versus 17% energy as protein) matched for sensory properties. Three hours after the preload, participants were offered an ad libitum meal. Food intake was weighed, perceived appetite was measured by 100 mm visual analogue scales, and gastric emptying via the 13C-octanoic acid breath test. Higher protein intake did not affect subsequent energy intake or appetite ratings in both active and less active groups. Gastric emptying half time was longer following the high-protein milkshake compared to the low-protein milkshake. The active group had a lower perceived appetite, but faster gastric emptying time compared to the less active group. In conclusion, while higher protein intake slows gastric emptying, it did not reduce appetite or subsequent food intake in older adults, regardless of physical activity level. Additionally, being physically active suppresses perceived appetite and accelerates gastric emptying without affecting food intake.

Dietary Recommendations for the Management of Gastrointestinal Symptoms in Patients Treated with GLP-1 Receptor Agonist

GLP-1 receptor agonist (GLP-1RA) have been developed to address the global burden of obesity and are renowned for their safety and efficacy. These medications influence hunger and satiety, reducing energy intake and promoting weight loss. Despite their benefits, GLP-1RAmay cause a slowed gastric emptying, leading to gastrointestinal symptoms. This study examines how food properties and meal composition affect these symptoms. Dietary recommendations are provided, particularly for evening meals, focusing on how different foods and nutrients can influence the rate of gastric emptying, to improve patient compliance and prevent interruption in weight loss.

The role of nutrient sensing dysregulation in anorexia of ageing: The little we know and the much we don't

The age-related decline in appetite and food intake - termed "anorexia of ageing" - is implicated in undernutrition in later life and hence provides a public health challenge for our ageing population. Eating behaviour is controlled, in part, by homeostatic mechanisms which sense nutrient status and provide feedback to appetite control regions of the brain. Such feedback signals, propagated by episodic gut hormones, are dysregulated in some older adults. The secretory responses of appetite-related gut hormones to feeding are amplified, inducing a more anorexigenic signal which is associated with reduced appetite and food intake. Such an augmented response would indicate an increase in gut sensitivity to nutrients. Consequently, this review explores the role of gastrointestinal tract nutrient sensing in age-related appetite dysregulation. We review and synthesise evidence for age-related alterations in nutrient sensing which may explain the observed hormonal dysregulation. Drawing on what is known regarding elements of nutrient sensing pathways in animal models, in other tissues of the body, and in certain models of disease, we identify potential causal mechanisms including alterations in enteroendocrine cell number and distribution, dysregulation of cell signalling pathways, and changes in the gut milieu. From identified gaps in evidence, we highlight interesting and important avenues for future research.

Understanding age-related changes: exploring the interplay of protein intake, physical activity and appetite in the ageing population

Globally, we are currently facing a rapid demographic shift leading to an increase in the proportion of older adults within the population. This raises concerns about the potential increase in age-related diseases and their impact on our ability to provide adequate health and end-of-life care. To apply appropriate interventions, understanding the changes that happen with ageing becomes essential. Ageing is often accompanied by a decrease in appetite and physical activity, which may lead to malnutrition, resulting in decreased muscle mass, physical capabilities and independence. To preserve muscle mass, older adults are advised to increase protein intake and physical activity. However, protein's high satiating effect may cause reduced energy intake. Physical activity is also advised to maintain or enhance older adult's appetite. This review paper aims to discuss appetite-related changes that occur with ageing and their consequences. In particular, it will focus on investigating the relationship between protein intake and physical activity and their impact on appetite and energy intake in the ageing population. Recent studies suggest that physical activity might contribute to maintaining or enhancing appetite in older adults. Nevertheless, establishing a definitive consensus on the satiating effect of protein in ageing remains a work in progress, despite some promising results in the existing literature.