Metabolic syndrome and changes in body fat from a low-fat diet and/or exercise randomized controlled trial

Abstract

It is difficult to identify the successful component(s) related to changes in metabolic syndrome (MetS) from lifestyle interventions: the weight loss, the behavior change, or the combination. The purpose of this study is to determine the effects of a weight-stable randomized controlled trial of low-fat diet and exercise, alone and in combination, on MetS. Men (n = 179) and postmenopausal women (n = 149) with elevated low-density lipoprotein cholesterol (LDL-C) and low high-density lipoprotein cholesterol (HDL-C) were randomized into a 1-year, weight-stable trial with four treatment groups: control (C), diet (D), exercise (E), or diet plus exercise (D+E). MetS was defined using a continuous score. Changes in MetS score (DeltaMetS) were compared between groups using analysis of covariance, stratified by gender and using two models, with and without baseline and change in percent body fat (DeltaBF) as a covariate. In men, DeltaMetS was higher for D vs. C (P = 0.04), D+E vs. C (P = 0.0002), and D+E vs. E (P = 0.02). For women, DeltaMetS was greater for D vs. C (P = 0.045), E vs. C (P = 0.02), and D+E vs. C (P = 0.004). After adjusting for DeltaBF, all differences between groups were attenuated and no longer significant. DeltaMetS were associated with DeltaBF for both men (P < 0.0001) and women (P = 0.004). After adjustment for DeltaBF, low-fat diet alone and in combination with exercise had no effect on MetS. The key component for MetS from low-fat diet and/or increased physical activity appears to be body fat loss.

Figure 1

Change in metabolic syndrome (MetS) score between groups in men and women. Model 1 is adjusted for baseline MetS score, cohort, age, and menopausal hormonal therapy (as appropriate). Model 2 adjusts for the previous covariates as well as baseline body fat (%) and the change in body fat (%). (a) Change in MetS scores between treatment groups in men (n = 179) showed differences between the control group vs. diet (P = 0.04), control group vs. diet plus exercise (P = 0.0002), and exercise vs. diet plus exercise (P = 0.02). Model 2 did not have any differences between groups in men. (b) Changes in scores between treatment groups in women (n = 149) showed differences in control vs. diet (P = 0.045), control vs. exercise (P = 0.02), and control vs. diet plus exercise (P = 0.004). Model 2 did not have any differences between groups in women. Asterisks denote significant differences for the change in percent body fat between treatment groups from baseline to follow-up.

Figure 2

Adjusted change in metabolic syndrome (MetS) scores by tertiles of body fat change (%) (tertile I: men (≥0.9%), women (≥1.2%); tertile II: men (0.9 to −2.3%), women (1.2 to −2.3%); tertile III: men (less than −2.3%), women (less than −2.3%)) in men (filled circles) and women (empty circles). Covariates included in the model were baseline body fat (%), age, cohort, and menopausal hormonal therapy (as appropriate). A decrease in MetS score is desirable. Differences occurred for men between change in MetS scores and tertile of body fat (%) change: tertile I vs. II (P = 0.003), II vs. III (P = 0.001), and I vs. III (P < 0.0001). In women, differences existed for the change in MetS score and tertile of body fat (%) change: II vs. III (P = 0.02), as well as I vs. III (P = 0.001).