Moderate weight reduction improves red cell aggregation and factor VII activity in overweight subjects

Objective: To investigate the effect of a dietary intervention to reduce body weight on red cell aggregation (RCA), factor VII activity, plasminogen activator inhibitor (PAI) activity, tissue plasminogen activator (t-PA) antigen, fibrinogen, whole blood and plasma viscosity, haematocrit and lipids. Design: Open single stranded study of dietary intervention for weight loss in a volunteer sample. Subjects: Forty-five subjects whose BMI exceeded 26 kg/m² were recruited and received dietetic advice designed to reduce body weight by 0.5 kg per week. Measurements: Body weight and waist and hip circumferences, dietary intake by seven day weighed inventory, RCA, factor VII activity, PAI activity, t-PA antigen, fibrinogen, whole blood and plasma viscosity, haematocrit and lipids. Results: After 12 weeks of dietary intervention there were reductions in body weight and BMI by 5.9 (s.d. 3.3) kg and 1.9 (s.d. 1.0) kg/m² respectively in males, and 4.1 (s.d. 2.9) kg and 1.6 (s.d. 1.1)kg/m² in females (p < 0.0001). Factor VII activity (P = 0.0043), RCA (P = 0.01) and t-PA antigen (P = 0.016) were reduced in females after weight reduction but no differences found in PAI activity, whole blood, plasma viscosity or haematocrit. The changes in factor VII activity and RCA were appropriate for the changes in BMI on the basis of the relationships of the risk factors with BMI in a cross sectional survey of a representative Scottish population. Plasma total cholesterol was reduced (P = 0.016) but HDL cholesterol and triglycerides remained unchanged. There were significant associations between the reductions in factor VII activity and BMI (r = 0.395, P = 0.013) and between the reductions in RCA and waist to hip ratio (r = 0.350, P = 0.04). No relationship was seen between changes in serum cholesterol and changes in factor VII activity or RCA. Conclusions: Modest weight loss, of 5% body weight, with conventional dietary intervention reduces two established risk factors for ischaemic heart disease (factor VII activity and RCA) which is generally elevated in those with increased body weight.