Document Type

Theses, Ph.D

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Available under a Creative Commons Attribution Non-Commercial Share Alike 4.0 International Licence

Publication Details

Successfully submitted for the award of Doctor of Philosophy |(Ph.D.) to the Technological University Dublin in 2001

Abstract

This thesis set out to provide an objective understanding of periodicity of eating in a group of free living adults, by determining the temporal pattern of nutrient intake during eating occasions throughout the day. A dietary assessment study was carried out using a 7-day estimated food diary in a sample of 133 adults recruited from a city local authority. During the survey period, respondents were met on at least three occasions to encourage and motivate them to follow their usual dietary habits and to record their intakes in a as detailed a manner as possible. A combination of quantification methods was used to obtain best estimates for the weights of all food and drink consumed, including a photographic food atlas, manufacturers’ information, the weighing of specific food and drinks, household measures and standard portion sizes. The food and drink information was coded to allow analysis of the data in terms of individual eating occasions. An eating occasion was coded to allow analysis of the data in terms of individual eating occasions. An eating occasion was coded to the nearest hour and included every item of food and drink consumed within an hourly period. Nutrient analysis was carried out using the FOODBASE program on each eating occasion of each of the seven days for each respondent. This program was specifically chosen as it allowed specification of the amount and type of fat used in preparing and cooking foods. The nutrient intake date was entered into SPSS to create a database, which contained every hour of each of the seven days for each respondent, together with the nutrient analysis data of every eating occasion, at the specific hour of consumption. This database was then used to determine the temporal pattern of nutrient intake during eating occasions throughout the day to address a number of questions. Eating occasions of non-nutritive value were not included in the analysis. Four data analysis approaches were explored in order to determine temporal patterns of eating. Only two of these approaches, the eating occasion methods and the eating occasion by individual method, were considered appropriate to represent the temporal pattern of mean nutrient intakes during eating occasions throughout the day in free-living individuals. The eating occasion method was used to determine the amounts of fat consumed during eating occasions of free-living adults on self-selected diets and this information was used to address, for the first time, whether test meals used in postprandial lipeamia studies represent the macronutrient content of eating occasions of free-living adults. Most test meals used in postprandial lipaemia studies contain between 20g and 140g of fat whereas (89%) eating occasions of the free-living adults in this study contained less than 40g of fat. The temporal pattern of fat intake revealed a low-fat high-carbohydrate eating pattern in the early morning hours, the time at which postprandial studies usually administer a single high-fat test meal. Overall, this study showed the usual prostprandial study protocol does not represent the free-living situation. The temporal pattern of eating was also determined to provide baseline date for the development of evidence based dietary guidelines that may involve specific eating occasions of the day and thus set out to make consumer messages more relevant. Three issues were addressed. Firstly, a comparison was made of the temporal pattern of macronutrient intake during eating occasions between high-gat and low-fat consumers. Similar temporal patterns of macronutrient intake were observed although high-fat consumers had great fat intakes (g) and as a result greater energy intakes (MJ) during almost every eating occasion than the low-fat consumers. Secondly, the effect of differences in periodicity of eating on mean daily macronutrient intakes and the temporal pattern of macronutrient intake during eating occasions was determined. The high eating frequency group had higher mean daily energy intakes (P=0.015) and higher proportions of energy from carbohydrate (P-0.006) and sugars (P=0.001) than the low eating frequency group, who had higher proportions of energy from protein (P=0.002). No difference in fat intakes (% energy) was observed between the groups. Similar temporal patterns of macronutrient intake were observed between groups. Thirdly, the day-of –the week effect on macronutrient intakes and the temporal pattern of eating between weekdays and weekend days were investigated. The main finding was a higher total energy intake (P=0.017) but not food energy intake on weekend vs. weekdays. Similar temporal patterns of macronutrient intake were observed between weekdays and weekend days. These investigations demonstrated the importance and value of studying date at the level of eating occasions. This study, however, is limited because of its small sample size. Food and nutrient intake findings of a small non-random population in a country must be also be observed in a random and representative sample of the population before recommendations can be formulated. As part of the North/South Ireland Food Consumption Survey a methodology was developed to ensure the data analysis could be conducted at the level of individual eating occasions. A description of the methodology used is presented in this thesis and the macronutrient intakes and food sources of this representative sample of Irish adults are described. Fat intakes (37% food energy) were higher than recommendations (35% food energy), carbohydrate intakes (46%) were lower than recommendations (50% + food energy). Protein intakes were adequate with 93% of men and 86% of women with protein intakes above the PRI (0.7g of protein/kg body weight/day)

DOI

https://doi.org/10.21427/D7D901

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