There is debate over the casual factors for the rise in body weight in the UK. The present study investigates whether increases between 1986 and 2000 for men and women were a result of increases in mean total energy intake, decreases in mean physical activity levels or both. Estimates of mean total energy intake in 1986 and 2000 were derived from food availability data adjusted for wastage. Estimates of mean body weight for adults aged 19 -64 years were derived from nationally representative dietary surveys conducted in 1986-7 and 2000 -1. Predicted body weight in 1986 and 2000 was calculated using an equation relating body weight to total energy intake and sex. Differences in predicted mean body weight and actual mean body weight between the two time points were compared. Monte Carlo simulation methods were used to assess the stability of the estimates. The predicted increase in mean body weight due to changes in total energy intake between 1986 and 2000 was 4·7 (95 % credible interval 4·2, 5·3) kg for men and 6·4 (95 % credible interval 5·9, 7·1) kg for women. Actual mean body weight increased by 7·7 kg for men and 5·4 kg for women between the two time points. We conclude that increases in mean total energy intake are sufficient to explain the increase in mean body weight for women between 1986 and 2000, but for men, the increase in mean body weight is likely to be due to a combination of increased total energy intake and reduced physical activity levels.Key words: Body weight: Obesity: Diet: Physical activity: Energy intakeThe obesity epidemic in the UK is well documented -the prevalence of obesity in adults doubled between 1980 and 1991 (1) and has risen by more than 50 % since, with more than half of all adults now either overweight or obese (2,3) . It is predicted that if current trends continue, then nearly 60 % of the population could be obese by 2050 (4) . Weight gain is a result of energy imbalance -total energy intake greater than total energy expenditure, where total energy expenditure consists of energy that is expended both by activity and by BMR. Both BMR and the amount of energy expended by activity are associated with body weight -the greater the mass of the body, the greater the energy required to move it around and the greater the BMR required to sustain it and vice versa. Often this relationship between body weight and energy expenditure is ignored, leading to false conclusions such as 'an increase in dietary energy intake of 100 kJ/d will result in an increase in body weight of x kg every year', when in reality the increase in energy intake will produce an increase in body weight in the short term, but the resultant increase in BMR and energy expended in activity will soon result in a new 'settling point' where body weight has reached a new, larger constant. A recent meta-analysis of studies that used the doubly labelled water technique has been used to estimate the relationship between body weight and total energy intake, taking into account the association between BMR, the amount...

90 ms). There was a modest inverse correlation between DF and OI of EGMs (R¼À0.58, p<0.001 Conclusions The classification of fractionated EGMs is very sensitive to user-selected characteristics. Interpretation of results of "fractionation maps" must take into account analysis techniques, OI appears the most promising at guiding appropriate ablation site.Abstract 051 Figure 1

A forty-year-old man experienced worsening heart failure four years following bilateral complicated total hip replacement. His condition was extensively worked up but no underlying pathology was immediately evident. Given the cobalt-chromium alloy component present in the hip arthroplasties, the raised cobalt blood levels, and a fitting clinical picture coupled with radiological findings, the patient underwent right hip revision. Evidence of biotribocorrosion was present on direct visualisation intraoperatively. The patient subsequently experienced symptomatic improvement (NYHA class III to class I) and echocardiography showed recovery of ejection fraction. Cobalt exists as a bivalent and trivalent molecule in circulation and produces a cytotoxicity profile similar to nanoparticles, causing neurological, thyroid, and cardiological pathology. Blood levels are not entirely useful as there is no identifiable conversion factor for levels in whole blood, serum, and erythrocytes which seem to act independently of each other. Interestingly cobalt cardiomyopathy is frequently compounded by other possible causes of cardiomyopathy such as alcohol and a link has been postulated. Definitive treatment is revision of the arthroplasty as other treatments are unproven.

No abstract