Weight loss associated with reduced intake of carbohydrate reduces the atherogenicity of LDL in premenopausal women
Faculty of Computing, Health and Science
School of Exercise, Biomedical and Health Science / Centre for Alzheimer's Disease
The effect of a 3-tier intervention including dietary modifications (ie, moderate energy restriction, decreased carbohydrate, increased protein), increased physical activity, and the use of carnitine as a dietary supplement was evaluated on plasma lipids and the atherogenicity of low-density lipoprotein (LDL) particles in a population of overweight and obese premenopausal (aged 20-45 years) women. Carnitine or a placebo (cellulose) was randomly assigned to the participants using a double-blind design. Carnitine supplementation was postulated to enhance fat oxidation resulting in lower concentrations of plasma triglycerides. Seventy women completed the 10-week protocol, which followed a reduction in their energy intake by 15% and a macronutrient energy distribution of 30% protein, 30% fat, and 40% carbohydrate. In addition, subjects increased the number of steps taken per day by 4500. As no differences were observed between the carnitine and placebo groups in all the measured parameters, all subjects were pooled together for statistical analysis. Participants decreased (P < .01) their caloric intake (between 4132.8 and 7770 kJ) and followed prescribed dietary modifications as assessed by dietary records. The average number of steps increased from 8950 ± 3432 to 12 764 ± 4642 (P < .001). Body weight, plasma total cholesterol, LDL cholesterol, and triglyceride were decreased by 4.5%, 8.0%, 12.3%, and 19.2% (P < .0001), respectively, after the intervention. Likewise, apolipoproteins B and E decreased by 4.5% and 15% (P < .05) after 10 weeks. The LDL mean particle size was increased from 26.74 to 26.86 nm (P < .01), and the percent of the smaller LDL subfraction (P < .05) was decreased by 26.5% (P < .05) after 10 weeks. In addition, LDL lag time increased by 9.3% (P < .01), and LDL conjugated diene formation decreased by 23% (P < .01), indicating that the susceptibility of LDL to oxidation was decreased after the intervention. This study suggests that moderate weight loss (<5% of body weight) associated with reduced caloric intake, lower dietary carbohydrate, and increased physical activity impacts the atherogenicity of LDL.