- Title
- The role of breakfast consumption on metabolism, body size and chronic disease risk amongst healthy adults
- Creator
- Quatela, Angelica
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2018
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Breakfast is often described as the most important meal of the day because it is believed to play an important role in preventing obesity and the development of chronic diseases such as diabetes and cardiovascular disease (CVD). However, there is insufficient and contradictory evidence to support this claim. This PhD describes four studies which further investigate the role of breakfast on metabolic rate, body composition and chronic disease risk markers. The first two studies were longitudinal analyses of a large, representative sample of Australian women, investigating first the association between breakfast cereal consumption and incident obesity and secondly the risk of developing diabetes, in mid-age women from the Australian Longitudinal Study of Women's Health (ALSWH. My analyses found that muesli consumption on its own or as a part of an oats based cereal group was significantly associated with a reduction in the risk of developing obesity and type 2 diabetes in women over a 12-year period. All-Bran was also found to be significantly protective against incident obesity in women over 12 years. No other breakfast cereal, including 'any breakfast cereal' (a variable that combined all breakfast cereal consumption) and 'higher fibre' (a variable used to combine the high fibre breakfast cereals) breakfast cereal consumption, were found to be significantly protective against obesity or diabetes risk. A systematic review, meta-analysis and meta-regression of randomised cross over design studies was then conducted to examine the evidence available about the role of consuming breakfast (of varying macronutrient composition and/or energy composition) on diet-induced thermogenesis (DIT). This is of particular interest as even small changes in DIT may have significant effects on body weight and/or body composition over the longer term. The findings of the meta-regression indicated that the magnitude of the increase in DIT was influenced by the amount of energy ingested in a breakfast meal (for every 100 kJ increase in energy intake (EI), DIT increased by 1.1 kJ/h (p < 0.001)). DIT was also influenced by macronutrient composition; meals with a high protein or carbohydrate content had higher DIT than high fat meals although this effect was not always significant. Furthermore, DIT was affected by the eating pattern of the meal: consuming the same meal as a single bolus eating event compared to multiple smaller meals or snacks was associated with a significantly higher DIT (meta-analysis, p= 0.02). While this analysis suggests that breakfast consumed as one meal may exert a protective effect on obesity, it must be interpreted with caution as it was based on short term (one day intervention) studies. A surprising finding of this systematic review was the lack of studies looking at DIT and breakfast over longer periods of time, therefore this SR could only make inferences based on short-term effects. The heterogeneous nature of the breakfast meals found in the literature while completing the SR, and the lack of recent evidence regarding what constitutes an habitual breakfast meal in Australia, led me to determine that more research was needed on what currently constitutes breakfast in multicultural Australia. The 'Typical Aussie Bloke' study was then formulated to address the lack of evidence about habitual breakfast habits among men and the fact that no data were available regarding habitual breakfast habits for an Australian population since the 1995 National Nutrition Survey. I investigated what foods and beverages currently constitute a typical breakfast amongst younger Australian men. A multi-site cross sectional study examined the breakfast habits of 112 young (18-44 y) Australian men, and found that the majority of men (83.5%) were Habitual Breakfast Eaters (HBE) (consumed breakfast .5 times/week) and 84% of them consumed breakfast between 5.01 to 8.00 am. A typical breakfast (.5 times/week) for the majority of HBE was a combination of one or more of the following foods and/or beverages: coffee (40.4%), breakfast cereal (50.0%), milk for cereal (51.1%), fruit (28.7%), toast (13.8%), spreads (11.7%), and/or yogurt (12.8%). This typical breakfast may also include (1-4 times/week) eggs (58.5%), bacon (30.9%), juice (19.1%), and/or tea (17.0%). In addition to examining breakfast habits in detail, the Typical Aussie Bloke Study investigated relationships between habitual breakfast consumption and the number of daily eating events, anthropometric measures, metabolic parameters and lifestyle characteristics of a sample of young Australian men. To the author's knowledge, there have been no other studies the size of the TAB that have collected detailed data on anthropometric and metabolic measurements and compared them with breakfast habits data, timing of breakfast consumption or eating frequency. However, the proportion of Habitual Breakfast Skippers (HBS) was low among our sample, limiting our ability to compare health and lifestyle variables among HBE and HBS. I did ascertain that certain socio-demographic characteristics were related to breakfast patterns. HBE were significantly more likely to have a university qualification (62.8%) than Occasional Breakfast Eaters (OBE) (28.6%) and HBS (20.0%). Early (before 8am) Breakfasts Eaters (EBE) were more likely to be older (p=0.0124), married (Early 59.4% vs Late 26.67p=0.023), have full time jobs (Early 69.8% vs Late 13.3%; p=0.01), earn . AUD50K (Early 69.7% vs Late 26.7%; p=0.043) and have more dependent children (Early 35.6% vs Late 6.7%, p=0.032). However, in both groups the majority of men in this study had no dependent children. It was also found that sleeping and waking habits did not differ significantly between HBE, OBE and HBS. However, differences were found amongst men consuming the breakfast meal Early vs Late, with a significantly higher proportion of EBE going to sleep before 11.00 pm and waking up before 8.00 am relative to Late Breakfast Eaters (LBE) (both p<0.001). Physical activity levels and fruit and vegetable consumption did not differ significantly between HBE, OBE and HBS, or between EBE and LBE. Although there was a significantly (p=0.015) higher percentage of HBE who consumed 5 or more daily eating events (59.6 %) in comparison to OBE (28.6%) and HBS (20%) who were instead more likely to eat 1-4 times/day. No differences in daily eating events were found amongst EBE vs LBE. Furthermore, differences in sleeping habits were found between men with different frequency of eating events. Men consuming 5 or more eating events per day (n=60; Frequent Eaters) were significantly more likely to go to sleep earlier than 11.00 pm (p=0.021) than men consuming 1-4 eating events per day (n=50; Less Frequent Eaters). Physical activity levels, fruit and vegetable consumption, and waking habits did not significantly differ between Frequent and Less Frequent Eaters. Metabolic and anthropometric parameters including BMI, waist, hip and chest circumferences, body composition, blood pressure, resting metabolic rate, blood glucose and lipid profiles did not differ between HBE, OBE and HBS; between EBE and LBE or between Frequent and Less Frequent Eaters. Overall, this PhD has contributed to an increased understanding of breakfast consumption and skipping in men, and the associations of different types of breakfast and breakfast cereal with risk factors related to the development of obesity or diabetes in women. The findings of this PhD do not support the concept that consumption of any type of breakfast or breakfast cereal may be associated with a reduction in risk factors related to the development of obesity or chronic disease risk. Instead, it suggests that the types of breakfast foods and/or breakfast composition may be important in any relationship between breakfast and health outcomes. This PhD work has also highlighted the lack of research examining the role of breakfast in longer term studies, suggesting the need to better investigate the role of breakfast in relation to total daily eating events, total daily energy intake and the overall quality of the diet. This would allow adjustment for other eating factors that may bias the association between breakfast consumption and health parameters. Finally, longer term intervention trials and cohort studies are needed to investigate the effects of breakfast consumption per se, different types of breakfast and breakfast cereal on daily eating patterns, on metabolism, body size and chronic disease risk in adults, using robust study designs and adequate sample sizes.
- Subject
- metabolism; breakfast; body size; chronic disease; healthy adults; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1384169
- Identifier
- uon:32021
- Rights
- Copyright 2018 Angelica Quatela
- Language
- eng
- Full Text
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