Sara Smith

Prenatal programming of postnatal obesity: fetal nutrition and the regulation of leptin synthesis and secretion before birth

The introduction of the process of nutritional screening into clinical standards has been driven by the increasing awareness of the prevalence of undernutrition in acute and primary care, along with its associated morbidity and mortality. However, the increasing prevalence of obesity in the general population suggests that an increased number of patients admitted to hospital will be obese. Increased morbidity has also been reported in the injured obese patient and may be associated with poor nutritional support. This situation may occur because the profound metabolic disturbances accompanying trauma in this group are not recognised, and subsequent feeding practices are inappropriate. Screening tools currently classify patients by using simple markers of assessment at the whole-body level, such as BMI. Subsequently, patients are identified as at risk only if they are undernourished. Such comparisons would by definition classify injured obese patients as at minimal or no nutritional risk, and they would therefore be less likely to be re-screened. This approach could result in potential increases in morbidity, length of rehabilitation and consequent length of hospital stay. It is likely that the identification of potential risk in obese injured patients goes beyond the measurement of such indices as BMI and percentage weight loss, which are currently utilised by the majority of screening processes.

Morphological and health-related changes associated with a 12-week self-guided exercise programme in overweight adults: a pilot study

Abstract Over 12 weeks, supervised physical activity (PA) interventions have demonstrated improvements in morphological and health parameters, whereas community walking programmes have not. The present study piloted a self-guided programme for promoting PA and reducing sedentary behaviour in overweight individuals and measured its effect on a range of health outcomes. Six male and 16 female sedentary adults aged 48.5 ± 5.5 years with body mass index (BMI) 33.4 ± 6.3 kg m−2 were assessed for anthropometric variables, blood pressure, functional capacity, well-being and fatigue. After an exercise consultation, participants pursued their own activity and monitored PA points weekly. At baseline, mid-point and 12 weeks, eight participants wore activity monitors, and all participants undertook a 5-day food diary to monitor dietary intake. In 17 completers, mass, BMI, sit-to-stand, physical and general fatigue had improved by 6 weeks. By 12 weeks, waist, sagittal abdominal diameter (SAD), diastolic blood pressure, well-being and most fatigue dimensions had also improved. Throughout the intervention, PA was stable, energy intake and lying time decreased and standing time increased; thus, changes in both energy intake and expenditure explain the health-related outcomes. Observed changes in function, fatigue and quality of life are consistent with visceral fat loss and can occur at levels of weight loss which may not be considered clinically significant.

Strategies to improve ingestive behaviour with reference to critical illness

The complex interplay between neural and endocrine responses following food intake regulates ingestive behaviour and ultimately determines subsequent energy intake. These processes include cognitive, gastrointestinal-derived and metabolic mechanisms. Such physiological responses to the ingestion of food initiate short- to medium-term inhibition of intake (satiety). However, in clinical states in which systemic inflammation is evident there is a more profound satiety response and a clear absence of motivation to eat that is evident as loss of appetite. These negative influences on energy intake can contribute to poor nutritional status, and consequently poor physical function, and impact on rehabilitation and recovery. Cytokine mediators of the inflammatory response directly influence feeding behaviour at the hypothalamic nuclei and may explain the lack of motivation and desire for food. However, additional detrimental effects on appetite are brought about because of alterations in intermediary metabolism present in inflammation-induced catabolism. This process forms part of the host response to inflammation and may explain symptoms, such as early satiety, frequently reported in many patient groups. In clinical states, and cancer in particular, pharmacological strategies have been employed to ameliorate the inflammatory response in an attempt to improve energy intake. Some success of this approach has been reported following administration of substrates such as EPA. Novel strategies to improve intake through administration of anti-cytokine drugs such as thalidomide may also be of benefit. However, drugs that oppose the actions of neurotransmitter pathways involved in central induction of satiety, such as 5-hydroxytryptamine, have failed to improve intake but appear to enhance enjoyment of food. Such findings indicate that therapeutic nutritional targets can only be achieved where novel pharmacological therapies can be supported by more innovative and integrated dietary management strategies. Many of these strategies remain to be elucidated.

The accuracy of mid upper arm circumference as an estimate of body mass index in healthy female adults

Equations developed by Powell-Tuck and Hennessy in 2003(1) allow an estimate of body mass index (BMI) to be determined from mid upper arm circumference (MUAC). These equations are widely used in clinical practice when an individuals BMI cannot be calculated from measured height and weight. Anecdotal reports also suggest that estimated BMI derived from these equations is being used along with height to estimate the weight of some individuals who cannot be weighed, which in turn is used to calculate nutritional requirements. Secondary analysis of data for individuals who participated in the National Diet and Nutrition Survey (aged 65 years or over) suggests that there is a substantial variability in BMI predicted from an individual MUAC(2). However there appears to be a lack of such data in younger adults. Therefore a pilot study aimed at assessing the accuracy of BMI estimated using the Powell-Tuck and Hennessy equations and the subsequent accuracy of estimated weight, within a younger healthy female adult population was undertaken. Subjects who volunteered had their age recorded, and actual height, weight and MUAC measured. From this data actual BMI, estimated BMI and estimated weight were calculated. The relationship between actual BMI and MUAC, actual BMI and estimated BMI were explored using pearsons correlation. The accuracy of estimated BMI with actual BMI and estimated weight with actual weight were determined using Bland-Altman limits of agreement. 29 subjects volunteered with a mean age of 26.1 years (standard deviation (SD) 10.2 years) and a mean actual BMI of 23.1 Kg/m2 (SD 4.3 Kg/m2). A strong positive (r=0.912), statistically significant (p<0.001) correlation between actual BMI and MUAC was identified, as was a strong positive correlation between actual BMI and estimated BMI (r=0.896). Bland-Altman analysis revealed a mean difference of −0.08 Kg/m2 for estimated BMI versus actual BMI and a mean difference of −0.16 Kg for estimated weight versus actual weight. However the 95% confidence intervals for estimated BMI versus actual BMI were −5.64 Kg/m2 to 4.10 Kg/m2 and −13.23 Kg to 12.91 Kg for estimated weight versus actual weight. The results demonstrate a strong positive relationship between BMI and MUAC, and between actual BMI and estimated BMI. However they also demonstrated that at an individual level both estimated BMI and estimated weight could be significantly over or under the actual value, to a level that could affect clinical practice by altering BMI classification and/or calculated nutritional requirements. Although further work is required to determine the accuracy of Powell-Tuck and Hennessy equations in other populations and to potentially derive more accurate equations, practitioners should be aware of the potential inaccuracies of using the Powell-Tuck and Hennessy equations to estimate an individuals BMI or to derive an individual estimation of weight.

Prevalence of sarcopenia in a Scottish cohort with chronic kidney disease (CKD) receiving haemodialysis and its association with clinical parameters

The presence of chronic kidney disease (CKD) has been suggested to elicit early onset reductions in lean body mass leading to disease related sarcopenia and poor functional performance. We investigated the prevalence of sarcopenia in a Scottish cohort receiving long term (>6 months) haemodialysis and its association with age, dialysis vintage, comorbidity and inflammation. The diagnosis of sarcopenia was based on the European consensus definition and diagnosis. Handgrip as a marker of muscle strength was measured pre dialysis. Height and weight were measured post dialysis for the calculation of body mass index (BMI). Calf circumference (CC) and mid arm muscle circumference (MAMC) were measured post dialysis as anthropometric estimates of muscle mass. Dual frequency bioelectrical impedance analysis (DFBIA) was also measured post dialysis to derive skeletal muscle index (SMI). Functional performance was assessed using the 6-minute walk test and number of sit-to-stand transitions performed in 1 minute. Comorbidity scores were determined using the Charlson co-morbidity index scoring system, monthly high sensitivity C-reactive protein (hsCRP) results were used to determine the presence of inflammation and dialysis vintage was calculated from the first date renal replacement therapy was initiated. Sixty-four patients were recruited 39 male & 25 female with a mean age of 54 years 16 (SD) and BMI of 27·6 Kg/m 6·3 (SD), mean hsCRP was 11·6 mgL 5·1 (SD), mean dialysis vintage was 75·0 months 84·8 (SD). 43·8% were identified as sarcopenic, with 26·6% presenting with severe sarcopenia. Sarcopenic obesity was present in 20·3%. Those with sarcopenia performed fewer sit-to-stand transitions and walked less distance in 6 minutes than those without sarcopenia. Whilst a significant difference in SMI was observed between those with and without sarcopenia, no difference in calf circumference or mid arm muscle circumference was evident.