We found that the 12 month weight loss intervention utilizing meal replacements and dietary counselling to reduce dietary fat intake and increasing physical activity led to substantial and significant favourable reductions in anthropometric and metabolic risk factors in both pre- and postmenopausal women.
The amount of weight loss in both groups was similar to other reported findings in premenopausal [14
] and postmenopausal [17
] women following comprehensive lifestyle interventions. The results further demonstrate that despite comparable weight loss, the intervention was associated with a considerably higher reduction in metabolic risk factors in postmenopausal women compared to premenopausal women.
In both groups the reduction of body weight was mainly due to a reduction in fat mass. In premenopausal women loss of fat free mass accounted for 21% of the total weight reduction, whereas in postmenopausal women the loss of muscle mass was rather small (< 3% of weight loss). This is encouraging as it demonstrates that weight reduction using this type of intervention in postmenopausal women is feasible without significantly reducing lean body mass. In the context of weight loss, the preservation of muscle mass is particularly important for maintenance of motor competence and metabolic capacity of skeletal muscles. Additionally, we have shown this to be true in a previous study. In this intervention study we found that through the use of a meal replacement (supply of high quality proteins) and adequate physical activity regimen significant weight reduction may be reached without losing muscle mass. [21
Fat mass and waist circumference were higher in postmenopausal women at the beginning of the study. This is in accordance with previous findings showing that weight gain during aging occurs predominantly in the abdominal region [22
]. Furthermore, it is known that after menopause, waist circumference and visceral adipose tissue accumulation increase beyond the effect of ageing [24
]. In our study, postmenopausal women exhibited a lower reduction of waist circumference compared to premenopausal women. This is in contrast to other studies employing regional analysis of body composition showing that abdominal fat and thigh fat were the regions most significantly affected by weight loss in postmenopausal women [25
]. However, methods applied in this study do not allow a further discrimination between different fat regions.
Nevertheless, there is accumulating knowledge that fat mass as well as the relation between muscle mass and fat mass are associated with the expression of metabolic and cardiovascular risk factors [26
]. In our study, postmenopausal women showed higher initial levels of systolic (BPsys) and diastolic blood pressure (BPdia), total cholesterol (TC), LDL-cholesterol (LDL-C), triglycerides (TG) plasma glucose (Gluc) and lower levels of HDL-Cholesterol (HDL-C). However, only differences for BPsys, TG and Gluc were significant. This underscores that the postmenopausal women investigated showed a considerable higher metabolic risk profile as presented in the NCEP ATP III criteria [28
]. After participating in the intervention, the percentage of postmenopausal women with the metabolic syndrome was reduced from 42 to 16% (p < 0.01) compared to a non-significant decrease from 23 to 18% in premenopausal women. The significant reduction in the prevalence of the metabolic syndrome in postmenopausal women demonstrates that despite a relatively smaller reduction in waist circumference and fat mass, the benefit of these changes is considerably greater in postmenopausal women with respect to the reduction in metabolic risk factors.
However, our data also show that premenopausal women experienced a significant reduction in cardiovascular risk factors. Elevated fasting levels of plasma insulin and impaired glucose tolerance have been widely recognized as major independent risk factors for the development of coronary heart disease [29
]. In both groups, fasting blood glucose was reduced. However, the reduction in insulin levels was only significant in the postmenopausal women. As insulin levels or insulin sensitivity have shown to be correlated to abdominal fat mass [30
], the decrease in insulin in postmenopausal women may be explained by the higher reduction of fat mass in this group.
The same differences were detected for cortisol, one of the counterparts of insulin action. Our results confirm the finding that higher levels of adiposity are associated with higher concentrations of serum leptin [31
]. Leptin levels were significantly reduced by reduction of fat mass in both groups. Despite a higher absolute reduction of fat mass in postmenopausal women, the proportion of fat mass remained higher in postmenopausal women at the end of the study. Therefore, postinterventional Leptin levels were still higher in postmenopausal women.
Doucet et al. described that during weight reduction the decrease in fasting plasma insulin was the only significant correlate of changes in fasting plasma leptin levels [32
]. In our study, reduction of insulin, leptin and cortisol was severalfold higher in the postmenopausal group.
Weight loss programs including pharmaceutical interventions have shown to be associated with considerable higher drop-out rates [33
]. In our study, the weight loss intervention was very well accepted by all participants as shown by the low drop-out rate. In an evaluation participants appreciated the personal counselling and the guided activity program as very helpful.