Michelle Spence

Low-fat versus low-carbohydrate weight reduction diets: effects on weight loss, insulin resistance, and cardiovascular risk: a randomized control trial.

OBJECTIVE Low-fat hypocaloric diets reduce insulin resistance and prevent type 2 diabetes in those at risk. Low-carbohydrate, high-fat diets are advocated as an alternative, but reciprocal increases in dietary fat may have detrimental effects on insulin resistance and offset the benefits of weight reduction. RESEARCH DESIGN AND METHODS We investigated a low-fat (20% fat, 60% carbohydrate) versus a low-carbohydrate (60% fat, 20% carbohydrate) weight reduction diet in 24 overweight/obese subjects ([mean ± SD] BMI 33.6 ± 3.7 kg/m2, aged 39 ± 10 years) in an 8-week randomized controlled trial. All food was weighed and distributed, and intake was calculated to produce a 500 kcal/day energy deficit. Insulin action was assessed by the euglycemic clamp and insulin secretion by meal tolerance test. Body composition, adipokine levels, and vascular compliance by pulse-wave analysis were also measured. RESULTS Significant weight loss occurred in both groups (P < 0.01), with no difference between groups (P = 0.40). Peripheral glucose uptake increased, but there was no difference between groups (P = 0.28), and suppression of endogenous glucose production was also similar between groups. Meal tolerance–related insulin secretion decreased with weight loss with no difference between groups (P = 0.71). The change in overall systemic arterial stiffness was, however, significantly different between diets (P = 0.04); this reflected a significant decrease in augmentation index following the low-fat diet, compared with a nonsignificant increase within the low-carbohydrate group. CONCLUSIONS This study demonstrates comparable effects on insulin resistance of low-fat and low-carbohydrate diets independent of macronutrient content. The difference in augmentation index may imply a negative effect of low-carbohydrate diets on vascular risk.

Effect of Eucaloric High- and Low-Sucrose Diets With Identical Macronutrient Profile on Insulin Resistance and Vascular Risk: A Randomized Controlled Trial

The long-term impact of dietary carbohydrate type, in particular sucrose, on insulin resistance and the development of diabetes and atherosclerosis is not established. Current guidelines for the healthy population advise restriction of sucrose intake. We investigated the effect of high- versus low-sucrose diet (25 vs. 10%, respectively, of total energy intake) in 13 healthy subjects aged 33 ± 3 years (mean ± SE), BMI 26.6 ± 0.9 kg/m2, in a randomized crossover design with sequential 6-week dietary interventions separated by a 4-week washout. Weight maintenance, eucaloric diets with identical macronutrient profiles and fiber content were designed. All food was weighed and distributed. Insulin action was assessed using a two-step euglycemic clamp; glycemic profiles were assessed by the continuous glucose monitoring system and vascular compliance by pulse-wave analysis. There was no change in weight across the study. Peripheral glucose uptake and suppression of endogenous glucose production were similar after each diet. Glycemic profiles and measures of vascular compliance did not change. A rise in total and LDL cholesterol was observed. In this study, a high-sucrose intake as part of an eucaloric, weight-maintaining diet had no detrimental effect on insulin sensitivity, glycemic profiles, or measures of vascular compliance in healthy nondiabetic subjects.

A qualitative study of psychological, social and behavioral barriers to appropriate food portion size control

BackgroundGiven the worldwide prevalence of overweight and obesity, there is a clear need for meaningful practical healthy eating advice - not only in relation to food choice, but also on appropriate food portion sizes. As the majority of portion size research to date has been overwhelmingly quantitative in design, there is a clear need to qualitatively explore consumers’ views in order to fully understand how food portion size decisions are made. Using qualitative methodology this present study aimed to explore consumers’ views about factors influencing their portion size selection and consumption and to identify barriers to appropriate portion size control.MethodsTen focus groups with four to nine participants in each were formed with a total of 66 persons (aged 19–64 years) living on the island of Ireland. The semi-structured discussions elicited participants’ perceptions of suggested serving size guidance and explored the influence of personal, social and environmental factors on their food portion size consumption. Audiotapes of the discussions were professionally transcribed verbatim, loaded into NVivo 9, and analysed using an inductive thematic analysis procedure.ResultsThe rich descriptive data derived from participants highlight that unhealthy portion size behaviors emanate from various psychological, social and behavioral factors. These bypass reflective and deliberative control, and converge to constitute significant barriers to healthy portion size control. Seven significant barriers to healthy portion size control were apparent: (1) lack of clarity and irrelevance of suggested serving size guidance; (2) guiltless eating; (3) lack of self-control over food cues; (4) distracted eating; (5) social pressures; (6) emotional eating rewards; and (7) quantification habits ingrained from childhood.ConclusionsPortion size control strategies should empower consumers to overcome these effects so that the consumption of appropriate food portion sizes becomes automatic and habitual.

An exploration of knowledge and attitudes related to pre-pregnancy care in women with diabetes

Diabet. Med. 27, 1385–1391 (2010)

Domestic cooking and food skills: A review

ABSTRACT Domestic cooking skills (CS) and food skills (FS) encompass multiple components, yet there is a lack of consensus on their constituent parts, inter-relatedness, or measurement, leading to limited empirical support for their role in influencing dietary quality. This review assessed the measurement of CS and FS in adults (>16 years); critically examining study designs, psychometric properties of measures, theoretical basis, and associations of CS/FS with diet. Electronic databases (PsychInfo), published reports, and systematic reviews on cooking and home food preparation interventions provided 834 articles of which 26 met the inclusion criteria. Multiple CS/FS measures were identified across three study designs—qualitative, cross-sectional, and dietary interventions—conducted from 1998 to 2013. Most measures were not theory-based, limited psychometric data were available, with little consistency of items or scales used for CS/FS measurements. Some positive associations between CS/FS and fruit and vegetables intake were reported, though lasting dietary changes were uncommon. The role of psycho-social (e.g., gender, attitudes) and external factors (e.g., food availability) on CS/FS is discussed. A conceptual framework of CS/FS components is presented for future measurement facilitation, which highlights the role for CS/FS on food-related behavior and dietary quality. This will aid future dietary intervention design.

Evaluation of a DVD for women with diabetes: impact on knowledge and attitudes to preconception care

Diabet. Med. 29, 950–956 (2012)

The connexin 37 gene polymorphism and coronary artery disease in Ireland

Coronary artery disease (CAD) and myocardial infarction (MI) are polygenic disorders caused by a complex interaction between environmental and genetic factors. A family history of MI is also an independent risk factor for MI.1 Several methods have been proposed to identify the underlying genetic cause of CAD, including genetic linkage studies and candidate gene approaches. CAD and MI are the clinical manifestations of underlying coronary atherosclerosis. The cornerstones of this process are elevated plasma lipid concentrations and inflammation. Central to this process is the relation between endothelial cells (EC) and smooth muscle cells (SMC). Connexins are members of a multigene gap junction family that may mediate EC-SMC communication. These transmembrane channels connect neighbouring cells allowing movement of small molecules and second messengers.2 The role of connexin 37 (CX37) and the C1019T polymorphism have been previously investigated in CAD and MI. The functional impact of the C1019T single nucleotide polymorphism has not been determined but it does result in a change in the amino acid sequence (Pro319Ser). A genome-wide search for susceptibility genes for MI identified a novel susceptibility locus on chromosomal region 1p34–36.3 This region contains the gene coding for CX37. The T allele of the C1019T polymorphism has been found to be significantly associated with the risk of MI in men and with CAD in high risk males,4 defined as those with hypertension, diabetes mellitus, …

Session 4: CVD, diabetes and cancer: Diet, insulin resistance and diabetes: the right (pro)portions.

Excess energy intake and positive energy balance are associated with the development of obesity and insulin resistance, which is a key feature underlying the pathophysiology of type 2 diabetes. It is possible that dietary macronutrient intake may also be important, in particular increased levels of sugar and fat. High-fat energy-dense diets contribute to energy excess and obesity. Fat type is also a factor, with evidence suggesting that saturated fat intake is linked to insulin resistance. However, controversy exists about the role of carbohydrate in the development of diabetes. Epidemiological studies suggest that the risk of diabetes is unrelated to the total amount of carbohydrate, but that fibre intake and glycaemic load are important. Common dietary advice for the prevention of diabetes often advocates complex carbohydrates and restriction of simple carbohydrates; however, sugars may not be the main contributor to glycaemic load. Evidence continues to emerge in relation to the influence of dietary sugars intake on insulin resistance. In broader dietary terms fruit and vegetable intake may influence insulin resistance, possibly related to increased intake of fibre and micronutrients or displacement of other food types. There is also considerable debate about the most effective diet and appropriate macronutrient composition to facilitate weight loss. Recent evidence suggests comparable effects of diets with varying macronutrient profiles on weight loss, which is predominantly related to energy restriction. However, based on the results of diabetes prevention trials focusing on lifestyle measures, evidence favours low-fat diets as the preferred approach for weight loss and diabetes prevention.

Are food-related perceptions associated with meal portion size decisions? A cross-sectional study

The purpose of this study was to test a comprehensive model of meal portion size determinants consisting of sociodemographic, psychological and food-related variables, whilst controlling for hunger and thirst. Using cross-sectional nationally representative data collected in 2075 participants from the Island of Ireland (IoI) and Denmark (DK), eight separate hierarchical multiple regression analyses were conducted to examine the association between food-related variables and meal portion size (i.e. pizza, vegetable soup, chicken salad and a pork meal) within each country. Stepwise regressions were run with physiological control measures (hunger and thirst) entered in the first step, sociodemographic variables (sex, age, body mass index (BMI)) in the second step; psychological variables (cognitive restraint, uncontrolled eating, emotional eating, general health interest (GHI)) in the third step and food-related variables (expected fillingness, liking, expected healthfulness, food familiarity) in the fourth step. Sociodemographic variables accounted for 2-19% of the variance in meal portion sizes; psychological variables explained an additional 3-8%; and food-related variables explained an additional 2-12%. When all four variable groups were included in the regression models, liking and sometimes expected healthfulness was positively associated with meal portion size. The strongest association was for liking, which was statistically significant in both countries for all meal types. Whilst expected healthfulness was not associated with pizza portion size in either country, it was positively associated with meals that have a healthier image (vegetable soup; chicken salad and in IoI, the pork meal). In conclusion, after considering sociodemographic and psychological variables, and the food-related variables of liking and expected healthfulness, there may be little merit in manipulating the satiating power, at least of these type of meals, to maintain or promote weight loss.

Investigation of the C242T polymorphism of NAD(P)H oxidase p22 phox gene and ischaemic heart disease using family-based association methods

Ischaemic heart disease is a complex phenotype arising from the interaction of genetic and environmental factors. Excessive production of reactive oxygen species leading to endothelial dysfunction is believed to be important in the pathogenesis of ischaemic heart disease. The NAD(P)H oxidase system generates superoxide anions in vascular cells; however, the role of the C242T polymorphism of the NAD(P)H oxidase p22 phox gene in ischaemic heart disease is unclear due to contradictory results from case-control studies. Consequently, we applied family-based association tests to investigate the role of this polymorphism in ischaemic heart disease in a well-defined Irish population. A total of 1023 individuals from 388 families (discordant sibships and parent/child trios) were recruited. Linkage disequilibrium between the polymorphism and ischaemic heart disease was tested using the combined transmission disequilibrium test (TDT)/sib-TDT (cTDT) and pedigree disequilibrium test (PDT). Both cTDT and PDT analyses found no statistically significant excess transmission of either allele to affected individuals (P =0.30 and P =0.28, respectively). Using robust family-based association tests specifically designed for the study of complex diseases, we found no evidence that the C242T polymorphism of the p22 phox gene has a significant role in the development of ischaemic heart disease in our population.