Franny Jongbloed

174 CHAPTER 7 Markers of metabolism and compliance Before and after all dietary interventions, blood samples were collected and serum and plasma was stored for further analyses. Only samples taken from fasted patients were used for these analyses. Due to the exclusion of samples from patients who did not fast, too few samples were available from the kidney donors for statistical analysis within this group. Therefore, the data from both kidney donors and morbidly obese patients were pooled. Due to a variation in baseline levels between the different patient groups, relative differences were compared between groups using the change in values before and after the intervention. Figure 3. Body weight changes in the three dietary intervention groups. Patients on the restricted diet lost an average of 2.5% of their body weight, corresponding to 2.4 ± 1.4 kg; This body weight loss was significantly greater than in the control group, which showed no change; The DER-diet resulted in a 1.7% loss in body weight (1.5 ± 1.4 kg), which was not significantly different than the two other groups; Changes are shown as percentages compared to the body weight at baseline; **P<0.01. Bars represent the standard error of the mean. DER = daily energy requirements. Metabolic changes due to the dietary interventions as well as intragroup variations were extensively assessed via a panel of 147 metabolic parameters (Table S1). The impact of the two diets on protein metabolismwas measured using serum albumin, urea and amino acids levels. The restricted diet did not significantly change serum albumin (Figure 4A). Serum albumin was increased by 7% after the DER-diet, but did not reach significance ( P= 0.006). The increase after the DER-diet showed a trend towards higher levels compared to the relative change in the restricted diet ( P= 0.006) and the control group ( P= 0.003) (Table 2). No significant changes were seen in the control group. Serum urea was on average 37.5% lower after the restricted diet than before the diet ( P= 0.002), which was also significantly different from the DER-diet ( P< 0.001) and the control group ( P< 0.001) (Figure 4B). There were no significant changes in serum urea in the DER-diet group or in the control group.