The relationship between physical activity, appetite and energy intake in older adults: A systematic review.

Ageing often causes a reduction in appetite and energy intake in older adults which can result in malnutrition. Current guidelines for older adults suggest increasing physical activity to enhance appetite. However, it is unclear if there is evidence to support this advice. This aim of this review is to assess if appetite and energy intake is changed in older adults that undertake acute or regular physical activity (measured from cross sectional and intervention studies). Databases SPORTDiscus, CINAHL, MEDLINE were searched for studies between 1970 and 2017 using search terms related to ageing, physical activity (including exercise), energy and appetite. Studies included contained adults over 60 years, including acute, cross-sectional and intervention (longitudinal) studies. Of 34 full-text articles assessed, 8 were included. The Cochrane Collaboration's tool was used for assessing risk of bias. No acute studies were found. Of the cross-sectional studies, one study suggested that individuals who undertake habitual physical activity had an increased energy intake and none of the studies found differences in appetite ratings. Energy intakes increased in the intervention studies, though not always sufficiently to maintain energy balance. One study showed that ability to correctly compensate for previous energy intake was better in those that undertake habitual physical activity. The limited number of studies, wide range of data collection methodologies, time-scales and interventions mean that definitive outcomes are difficult to identify. At this stage advice to increase acute or habitual physical activity as a mean to increase appetite is not supported by sufficient evidence.

Coconut oil has less satiating properties than medium chain triglyceride oil.

It is well established that the consumption of medium-chain triglycerides (MCT) can increase satiety and reduce food intake. Many media articles promote the use of coconut oil for weight loss advocating similar health benefits to that of MCT. The aim of this study was to examine the effect of MCT oil compared to coconut oil and control oil on food intake and satiety. Following an overnight fast, participants consumed a test breakfast smoothie containing 205kcal of either (i) MCT oil (ii) coconut oil or (iii) vegetable oil (control) on three separate test days. Participants recorded appetite ratings on visual analogue scales and were presented with an ad libitum lunch meal of preselected sandwiches 180min after consumption of the breakfast. The results showed a significant difference in energy and macronutrient intakes at the ad libitum meal between the three oils with the MCT oil reducing food intake compared to the coconut and control oil. Differences in food intake throughout the day were found for energy and fat, with the control having increased food intake compared to the MCT and coconut. The MCT also increased fullness over the three hours after breakfast compared to the control and coconut oils. The coconut oil was also reported as being less palatable than the MCT oil. The results of this study confirm the differences that exist between MCT and coconut oil such that coconut oil cannot be promoted as having similar effects to MCT oil on food intake and satiety.

They say coconut oil can aid weight loss, but can it really?

There has in recent years, been much media speculation and consumer interest in the beneficial satiating properties of consuming coconut oil and its potential to aid weight loss. However, the media has primarily cited studies using medium-chain triglycerides (MCT) oil. The current perspective looks at the research that is available on coconut oil. It examines if and how MCT-related research can be applied to coconut oil and if there is potential for coconut oil to aid weight loss. The current report indicates a lack of consistent evidence on the topic of coconut oil, satiety and weight loss. Given both the publicity and the increased consumption of coconut oil further research, particularly long-term clinical trials, in this area are warranted.

Applying an extended theory of planned behaviour to predict breakfast consumption in adolescents.

BACKGROUND/OBJECTIVES: Breakfast skipping increases during adolescence and is associated with lower levels of physical activity and weight gain. Theory-based interventions promoting breakfast consumption in adolescents report mixed findings, potentially because of limited research identifying which determinants to target. This study aimed to: (i) utilise the Theory of Planned Behaviour (TPB) to identify the relative contribution of attitudes (affective, cognitive and behavioural) to predict intention to eat breakfast and breakfast consumption in adolescents and (ii) determine whether demographic factors moderate the relationship between TPB variables, intention and behaviour. SUBJECTS/METHODS: Questionnaires were completed by 434 students (mean 14±0.9 years) measuring breakfast consumption (0-2, 3-6 or 7 days), physical activity levels and TPB measures. Data were analysed by breakfast frequency and demographics using hierarchical and multinomial regression analyses. RESULTS: Breakfast was consumed everyday by 57% of students, with boys more likely to eat a regular breakfast, report higher activity levels and report more positive attitudes towards breakfast than girls (P<0.001). The TPB predicted 58% of the variation in intentions. Overall, the model was predictive of breakfast behaviours (P<0.001), but the relative contribution of TPB constructs varied depending on breakfast frequency. Interactions between gender and intentions were significant when comparing 0-2- and 3-6-day breakfast eaters only highlighting a stronger intention-behaviour relationship for girls. CONCLUSIONS: Findings confirm that the TPB is a successful model for predicting breakfast intentions and behaviours in adolescents. The potential for a direct effect of attitudes on behaviours should be considered in the implementation and design of breakfast interventions.

Oral versus intubated feeding and the effect on glycaemic and insulinaemic responses, gastric emptying and satiety.

Cephalic phase responses (CPR) are important in early initiation of digestion and maximal absorption of nutrients prior to ingestion. Bypassing CPR has been shown to have consequences on metabolic responses that may influence satiety. The aim of this study was to investigate if using gastric intubation to bypass oro-pharyngeal and oesophageal exposure would reduce CPR including insulin and blood glucose and whether these impact on gastric emptying and satiety. Ten male subjects were tested on 2 occasions, 3-7 days apart after an overnight fast, in randomized order. Subjects were cannulated and intubated with a gastric tube for both tests. For test one, subjects ate 400 ml soup with a spoon and for test two the soup was infused into the stomach at an equivalent rate. Subsequently measurements of glycaemic (GR) and insulinaemic responses (IR) from cannula samples, breath samples for measurement of gastric emptying using the [(13)C] sodium acetate breath test and visual analogue scales (VAS) for satiety were taken over 180 min. There were differences in IR over the first 15 min (Oral: 169.0 ± 22.1; Gastric 124.1 ± 18.8; t(9) = 2.67; p = 0.028) but no difference in GR. There were differences in gastric emptying half time (Oral: 85.0 ± 2.7; Gastric 79.4 ± 3.3; t(9) = 2.40; p = 0.04) and ascension time (Oral: 68.2 ± 2.2; Gastric 64.0 ± 2.2; t(9) = 2.57; p = 0.03) with food taking longer to empty from the stomach on the Oral test day than on the Gastric test day. There was no significant difference in the satiety ratings. This study demonstrated that bypassing oro-pharyngeal and oesophageal exposure decreases the normal physiological CPR with detriment to IR and gastric emptying.

A comparison of body composition measurement techniques.

BACKGROUND: An understanding of the reproducibility of body composition measurements is essential for effective intervention studies. Air displacement plethysmography (ADP) and bioelectrical impedance (BIA) are two easy-to-use measures of body composition. The present study aimed to assess the reproducibility of ADP and BIA and compare them with each other, as well as with skinfold measurement. METHODS: Forty-one participants were tested on two occasions following an overnight fast. On test day 1, participants' height, weight and % body fat (BF) were measured using ADP and BIA. Measurements were replicated to assess the within-day reproducibility. On test day 2, participants were again tested using ADP and BIA and had skinfold measurements taken. Three skinfold equations for BF calculation were applied. Comparisons of within- and between-day reproducibility and between measurement techniques were completed using Pearson correlations and Bland-Altman analysis. RESULTS: Both Pearson correlation and Bland-Altman analysis showed good within- and between-day relationships and agreement for BF from ADP and BIA measurements. The two methods had a high correlation between them; however, the mean difference between the two was 3.1% (4.1%). From the skinfold equations used, the best agreement with ADP had a mean difference of 0.3% (0.8%) and, with BIA, had mean differences of 1.9% (4.2%). CONCLUSIONS: The data indicate that ADP and BIA cannot be used interchangeably, although both measurements had good within- and between-day agreement.

Comparison of the GEM and the ECAL indirect calorimeters against the Deltatrac for measures of RMR and diet-induced thermogenesis.

The Deltatrac™ II Metabolic Monitor (Datex-Ohmeda Inc.) is considered the standard reference machine in indirect calorimetry; however, it is no longer commercially available thus there is a need for new machines. The gas exchange measurement (GEM; GEM Nutrition Ltd) and the ECAL (Health Professional Solutions) are alternative measuring systems. The aim of this study was to compare the ECAL and GEM with Deltatrac for measures of RMR and the GEM to the Deltatrac for measures of diet-induced thermogenesis (DIT). Twenty healthy participants were tested on test day 1 (T1) and test day 2 (T2). RMR was measured in a randomised order for 30 min on the Deltatrac, the GEM and the ECAL. Following this, a 1553 kJ meal was consumed and DIT was measured on the Deltatrac and the GEM in alternating 15 min intervals for 4 h. The GEM reported consistently higher values than the Deltatrac for VO2, VCO2, RMR and fat oxidation (P < 0·005). The ECAL was significantly higher than the Deltatrac for measures of VO2, RMR, carbohydrate oxidation (T2) and respiratory quotient and fat oxidation (T1, T2) (P < 0·05). There were no significant differences within repeated RMR measures on the ECAL, the GEM or the Deltatrac. DIT measures were consistently higher on the GEM (T1) (P < 0·005); however, there were no significant differences between repeated measures. The findings suggest that while the GEM and the ECAL were not accurate alternatives to the Deltatrac, they may be reliable for repeated measures.

Molecular weight of barley ß-glucan influences energy expenditure, gastric emptying and glycaemic response in human subjects.

Barley ß-glucan (BG) has been shown to reduce glycaemic response (GR) in some studies. It is hypothesised that this reduction may be a function of its physical properties that delay gastric emptying (GE). The effect of these changes in GR and GE on diet-induced thermogenesis (DIT) is not known. The aim of the present study was to assess the effect of BG of different molecular weights and purities on GR, GE and DIT in healthy subjects. This was a randomised, single-blind, repeated-measures design where fifteen healthy subjects were tested on three occasions following an overnight fast. Following the baseline measurements, the volunteers were fed a soup containing high-molecular-weight BG (HBG), a soup containing low-molecular-weight BG (LBG) or a control soup with no BG (CHO). Following the consumption of the breakfast, GR was measured using finger-prick blood samples, GE was determined using the 13C-octanoic acid breath test and DIT was measured using indirect calorimetry. There was a difference in GR AUC between the soups after 60 min but not after 120 min. The CHO and LBG meals had a greater GR than the HBG meal. There were differences in all GE time points, with the HBG meal having the slowest GE time. There was a correlation between the GR and the initial GE times. There were differences in total DIT between the three test meals with the HBG meal having the lowest DIT. The present study indicates that HBG has the ability to delay GE due to increased viscosity, resulting in a decreased GR and DIT.

Soups increase satiety through delayed gastric emptying yet increased glycaemic response.

BACKGROUND/OBJECTIVES: Previous studies have demonstrated the satiating properties of soups compared with solids; however, the mechanisms controlling soup-induced satiety are unknown. This study aimed to understand the physiological mechanisms causing soup to be more satiating. SUBJECTS/METHODS: A total of 12 volunteers were tested on three occasions after a solid meal, chunky soup or smooth soup test meal for gastric emptying (GE) using the sodium [1-¹³C] acetate breath test, satiety using visual analog scales (VAS) and glycaemic response (GR) using finger prick blood samples. RESULTS: There was a significant difference in GE half-time (P=0.022) and GE ascension time (P=0.018), with the longest GE times for the smooth soup and the shortest for the solid meal. The GR area under the curve was significantly different between meals (P=0.040). The smooth soup had the greatest GR (87.0 ± 49.5 mmol/l/min), followed by the chunky soup (65.4 ± 48.0 mmol/l/min), with the solid meal having the lowest GR (61.6 ± 36.8 mmol/l/min). Volunteers were fuller after the smooth soup compared with solid meal (P=0.034). CONCLUSIONS: The smooth soup induced greater fullness compared with the solid meal because of a combination of delayed GE leading to feelings of gastric distension and rapid accessibility of nutrients causing a greater glycaemic response.

Gastrointestinal transit, post-prandial lipaemia and satiety following 3 days high-fat diet in men.

BACKGROUND/OBJECTIVES: High-fat (HF) diets of 2 weeks have been shown to accelerate gastric emptying (GE). To date, no studies have shown any alteration in GE following shorter HF diets. The aim of this study was to assess if an HF, high-energy diet of 3 days can adapt gastrointestinal (GI) transit, blood lipids and satiety. SUBJECTS/METHODS: Eleven male volunteers participated in a study consisting of three, 3-day interventions each separated by a test day. During the first intervention, volunteers recorded their diet. In the second and third interventions, volunteers repeated their food diary plus either a low-fat yogurt or HF yogurt supplement in randomized order. Test days involved measurement of GE using the (13)C octanoic-acid breath-test, mouth-to-caecum transit time (MCTT) using the inulin H(2) breath test and satiety using visual analogue scales. Blood samples for measurement of lipaemia were taken using a venous cannula. RESULTS: MCTT was different between the three test days (P=0.038), with the shortest MCTT following the HF intervention. GE was shortest following the HF intervention. There were no differences in satiety between the interventions. The HF intervention reduced triglycerides, total cholesterol and low-density lipoprotein cholesterol, and increased high-density lipoprotein cholesterol. CONCLUSION: This study shows that changes in GI transit owing to an HF diet can occur in a time period as short as 3 days.