ORCID Profile
0000-0002-5484-292X
Current Organisation
University of Aberdeen
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Publisher: Elsevier BV
Date: 2014
DOI: 10.1016/J.ORCP.2012.07.006
Abstract: The accurate measurement of changes in body composition is important to assess the contribution of fat and fat free mass to total body mass change as a measure of the effectiveness of weight loss programmes. Bioelectrical impedance spectroscopy (BIS) is a rapid and non-invasive technique which could be applied to assess body composition changes. The aim of the study was to evaluate the accuracy of the BIS for the measurement of fat mass (FM), total body water (TBW) and extracellular water (ECW) changes induced by different degrees of caloric deficit in obese men. Three groups of six, obese men participated in either (i) a total fast (for 6 days) (ii) a VLCD (2.5 MJ/day for 3 weeks) or (iii) LCD (5.2 MJ/day for 6 weeks). FM was measured using a 4-compartment (4-C) model. TBW and ECW were determined by dilution methods, respectively. TBW, ECW and FM were also assessed with BIS. Body weight loss in the fasting group was 6.0 ± 1.3 kg over 6 days the VLCD group lost 9.2 ± 1.2 kg over 21 days and the LCD group lost 12.6 ± 2.4 kg over 42 days. BIS underestimated FM changes (bias = -3.3 ± 3.8 kg) and overestimated changes in TBW and ECW by +1.8 ± 4.8 kg and +2.3 ± 6.4 kg, respectively. The measurement error was consistently larger in the fasting group and the magnitude of the bias interacted significantly with the rate of weight loss. Rapid weight loss affects the accuracy of the BIS in detecting changes in body composition. A careful interpretation of the results is needed when sizable changes in body water compartments occurs.
Publisher: S. Karger AG
Date: 2009
DOI: 10.1159/000248277
Publisher: Springer Science and Business Media LLC
Date: 09-02-2010
DOI: 10.1038/IJO.2010.9
Abstract: The cellular model of body composition ides the body in body cell mass (BCM), extracellular solids and extracellular fluids. This model has been infrequently applied for the evaluation of weight loss (WL) programmes. (1) To assess changes in body compartments in obese men undergoing fasting, very low calorie diet (VLCD) and low calorie diet (LCD) (2) to evaluate two cellular models for the determination of changes in BCM, fat mass (FM) and body fluids. Three groups of six, obese men participated in a total fast (F) for 6 days, a VLCD (2.5 MJ per day) for 3 weeks or an LCD (5.2 MJ per day) for 6 weeks. Body composition was measured at baseline and after small ( approximately 5%) and moderate ( approximately 10%) WL. FM was measured using a four-compartment model. Total body water (TBW) and extracellular water (ECW) were, respectively, measured by deuterium and sodium bromide dilution and intracellular water (ICW) calculated by difference. Two cellular models were used to measure BCM, FM and body fluids distribution. After about 5%WL changes in TBW were F=-3.2+/-1.2 kg (P<0.01), VLCD=-1.2+/-0.6 kg (P<0.01), LCD=-0.3+/-0.9 kg(n.s.). The contribution of TBW to total body mass loss was indirectly associated with FM loss. ECW increased during fasting (+1.5+/-3.1 kg, n.s.), decreased during the VLCD (-2.0+/-1.5 kg, P<0.05) and remained unchanged at the end of the LCD (-0.3+/-1.6 kg, n.s.). ICW significantly decreased during fasting (-4.7+/-3.9 kg, P<0.05) but did not change in the LCD and VLCD groups. The loss of BCM was more significant in the fasting group and it was directly associated with changes in ICW. After a 6-day period of fasting we observed more ICW losses and less fat mobilization compared with VLCD and LCD. The cellular model of body composition is suitable for the characterization of changes in body fluids distribution during WL.
Publisher: Cambridge University Press (CUP)
Date: 06-2007
DOI: 10.1017/S0007114507691934
Abstract: One approach to achieve weight loss and decrease both obesity and associated morbidities involves high-protein, low-carbohydrate (HPLC) diets. This study compares the impact on metabolic health of HPLC and high-protein, medium-carbohydrate (HPMC) diets offered to diet-induced obese (DIO) rats. Weanling male rats were fed either a 37 % fat diet ( n 48) or stock pellets ( n 12) for 22 weeks. Rats fed the 37 % fat diet accumulated more body fat (26·6 versus 14·8 % body weight, P 0·001) compared with those on stock diet. The DIO rats had higher systolic blood pressure (+6·6 mmHg, P = 0·002), fasting insulin (+63 % P = 0·006) and areas under the glucose (+21 %, P 0·001) and insulin (+81 %, P 0·001) curves following an oral glucose tolerance test. DIO rats were then separated into four groups and offered for 8 weeks either: (1) the 37 % fat diet (2) an HPLC or (3) HPMC diet or (4) fed the 37 % fat diet to the intake of the HPMC group. Rats offered the 37 % fat or HPLC diets gained while those on HPMC lost body fat. Blood pressure was not altered by the dietary switch. Both HPLC and HPMC rats had lowered fasting insulin ( P = 0·027) and improved homeostatic assessment (HOMA P = 0·011) that was not different from those of stock animals. These improvements occurred despite differences in fat gain, and indicate that both weight loss and macronutrient intake can impact favourably on obesity-associated morbidities.
Publisher: Elsevier BV
Date: 08-2015
DOI: 10.1016/J.METABOL.2015.03.011
Abstract: Weight loss (WL) is associated with a decrease in total and resting energy expenditure (EE). We aimed to investigate whether (1) diets with different rate and extent of WL determined different changes in total and resting EE and if (2) they influenced the level of adaptive thermogenesis, defined as the decline in total or resting EE not accounted by changes in body composition. Three groups of six, obese men participated in a total fast for 6 days to achieve a 5% WL and a very low calorie (VLCD, 2.5 MJ/day) for 3 weeks or a low calorie (LCD, 5.2 MJ/day) diet for 6 weeks to achieve a 10% WL. A four-component model was used to measure body composition. Indirect calorimetry was used to measure resting EE. Total EE was measured by doubly labelled water (VLCD, LCD) and 24-hour whole-body calorimetry (fasting). VLCD and LCD showed a similar degree of metabolic adaptation for total EE (VLCD = -6.2% LCD = -6.8%). Metabolic adaptation for resting EE was greater in the LCD (-0.4 MJ/day, -5.3%) compared to the VLCD (-0.1 MJ/day, -1.4%) group. Resting EE did not decrease after short-term fasting and no evidence of adaptive thermogenesis (+0.4 MJ/day) was found after 5% WL. The rate of WL was inversely associated with changes in resting EE (n = 30, r = 0.-42, p=0.01). The rate of WL did not appear to influence the decline in total EE in obese men after 10% WL. Approximately 6% of this decline in total EE was explained by mechanisms of adaptive thermogenesis.
Publisher: Springer Science and Business Media LLC
Date: 04-2001
Abstract: To quantitatively assess subjects' ability to detect hedonic (palatability), sensory and nutritional differences between covertly manipulated high-fat (HF) and low-fat (LF) diets. SUBJECTS AND DIETS: This study examined the response of 16 subjects (eight men, eight women) to 20 LF and 20 HF versions of manipulated foods. Average percentage protein:fat:carbohydrate (by energy) and energy density (ED) of the two diets were 13:25:62, 371 kJ/100 g and 13:50:37, 672 kJ/100 g, respectively. Subjects were asked to simultaneously assess the HF and LF versions of each food in terms of (i) subjective pleasantness of each food, (ii) perceived differences in appearance, smell, taste and texture of the foods, and (iii) for each s le to assess whether it was high or low in energy, protein, carbohydrate, fat, fibre, sugar and salt. Perceived pleasantness of HF and LF versions of the foods was compared by analysis of variance. Comparisons used chi-squared tests of independence to assess departure from the null hypothesis of no perceived difference in remaining parameters (ii-iii). On average, subjects exhibited no significant preference for LF or HF versions of the foods (no difference 15 foods, three HF foods more pleasant, two LF foods more pleasant (P<0.03)). On average there were no general differences in comparison of sensory attributes that were consistently ascribable to the LF or HF foods, although there were numerous significant differences for in idual foods. Subjects appeared unable to distinguish the HF foods as being HF (66% of estimates) and guessed correctly 33% of the time. They were better able to categorize the LF foods correctly (53% correct). On aggregate 43% of HF and LF foods were correctly identified. Subjects appeared able to detect sensory differences between foods but not to relate them to energy or nutrient content of these foods. These data suggest that subjects are on average not able to perceive large differences in the fat content of diets manipulated in this manner. In general the assumption that the manipulation of such foods is covert appears to hold, but subjects were far better at correctly identifying certain food types (dairy-based) over others.
Publisher: MDPI AG
Date: 12-10-2023
DOI: 10.3390/SU152014783
Publisher: Canadian Science Publishing
Date: 08-2014
Abstract: The 4-component (4-C) model is the reference method to measure fat mass (FM). Simpler 2-component (2-C) models are widely used to assess FM. We hypothesised that an aggregate 2-C model may improve accuracy of FM assessment during weight loss (WL). One hundred and six overweight and obese men and women were enrolled in different WL programs (fasting, very low energy diet, low energy diet). Body density, bone mineral content, and total body water were measured. FM was calculated using 2-C, 3-C, and 4-C models. Aggregate equations for 2-C, 3-C, and 4-C models were calculated, with the aggregate 4-C model assumed as the reference method. The aggregate approach postulates that the average of the in idual estimates obtained from each model is more accurate than the best single measurement. The average WL was −7.5 kg. The agreement between 3-C and 4-C models for FM change was excellent (R 2 = 0.99). The aggregate 2-C equation was more accurate than in idual 2-C estimates in measuring changes in FM. The aggregate model was characterised by a lower measurement error at baseline and post-WL. The relationship between the aggregate 3-C and 4-C component models was highly linear (R 2 = 0.99), whereas a lower linearity was found for the aggregate 2-C and 4-C model (R 2 = 0.72). The aggregate 2-C model is characterised by a greater accuracy than commonly applied 2-C equations for the measurement of FM during WL in overweight and obese men and women.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Alexandra Johnstone.