Does provision of additional dietary information affect actual or only reported compliance to a low-fat diet over 12 weeks in hyperlipidaemic individuals? Report of a pilot study

This randomized controlled pilot study was designed to measure the effect of additional dietary information on change in reported percentage energy from fat (% fat), total daily energy intake (TDEI), body mass index (BMI) and serum cholesterol in 13 hyperlipidaemic subjects, referred from the Cardiology Unit of St. Bartholomew's Hospital, over 12 weeks. At baseline (visit 1), % fat and TDEI were assessed using a validated food frequency questionnaire (Paisley et al ., 1996), and BMI and fasting lipids were measured. «Standard>> low-fat dietary advice was given to all patients. Subjects were randomized at 4 weeks (visit 2) to receive either further «standard>> dietary advice (control group) or further «standard>> dietary advice plus an additional information package (intervention group). At 12 weeks (visit 3), % fat, TDEI, BMI and fasting lipids were reassessed. Both groups reported a significant reduction in % fat; a 23% reduction ( P =0.00) in the intervention group, and an 11% reduction ( P =0.005) in the control group. However, there was no significant difference in the reported % fat at the end of the study between the two groups ( P =0.57). Plasma cholesterol was not significantly reduced in either the intervention or the control group (mean 7.3–6.7 mmol/l, 7.2–6.6 mmol/l, respectively). Reported energy intake was significantly reduced in both groups, but the extent of energy reduction was not reflected in the degree of weight lost. These results suggest that the provision of additional dietary information affects reported rather than actual compliance to a low-fat diet.