Effects of Diet Composition and Insulin Resistance Status on Plasma Lipid Levels in a Weight Loss Intervention in Women

Abstract

BackgroundOptimal macronutrient distribution of weight loss diets has not been established. The distribution of energy from carbohydrate and fat has been observed to promote differential plasma lipid responses in previous weight loss studies, and insulin resistance status may interact with diet composition and affect weight loss and lipid responses.Methods and ResultsOverweight and obese women (n=245) were enrolled in a 1‐year behavioral weight loss intervention and randomly assigned to 1 of 3 study groups: a lower fat (20% energy), higher carbohydrate (65% energy) diet; a lower carbohydrate (45% energy), higher fat (35% energy) diet; or a walnut‐rich, higher fat (35% energy), lower carbohydrate (45% energy) diet. Blood samples and data available from 213 women at baseline and at 6 months were the focus of this analysis. Triglycerides, total cholesterol, and high‐ and low‐density lipoprotein cholesterol were quantified and compared between and within groups. Triglycerides decreased in all study arms at 6 months (P<0.05). The walnut‐rich diet increased high‐density lipoprotein cholesterol more than either the lower fat or lower carbohydrate diet (P<0.05). The walnut‐rich diet also reduced low‐density lipoprotein cholesterol in insulin‐sensitive women, whereas the lower fat diet reduced both total cholesterol and high‐density lipoprotein cholesterol in insulin‐sensitive women (P<0.05). Insulin sensitivity and C‐reactive protein levels also improved.ConclusionsWeight loss was similar across the diet groups, although insulin‐sensitive women lost more weight with a lower fat, higher carbohydrate diet versus a higher fat, lower carbohydrate diet. The walnut‐rich, higher fat diet resulted in the most favorable changes in lipid levels.Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT01424007.

Effects of diet composition on weight loss, metabolic factors and biomarkers in a 1-year weight loss intervention in obese women examined by baseline insulin resistance status

“…The overall rationale and context of this randomized controlled trial has been published previously [10], and the plasma lipid responses at the 6-month interim follow-up time point have been previously reported [31]. As previously described [31], study participants were nondiabetic overweight and obese women.…”

“…As previously described [31], study participants were nondiabetic overweight and obese women. The UCSD institutional review board approved the study protocol, and all participants provided written informed consent.…”

“…Details about the diet prescription and intervention have been previously published [31]. Briefly, the overall goal of the dietary guidance was to promote a 500-1000 kcal/day deficit relative to expenditure.…”

Dietary intake of antioxidants and fats in the context of coronary heart disease prevention among elderly people

“…Most nuts contain monounsaturated fatty acids, and walnuts are a rich source of polyunsaturated fatty acids, particularly the omega-3 fatty acids, alfa-linolenic acid, and omega-6 linoleic acid. Walnuts also provide antioxidants (tocopherols, phenolic compounds and allagic acid [30,31]. [17].…”

Overnutrition, Ectopic Lipid and the Metabolic Syndrome

“…In obese individuals, caloric restriction is followed by loss of adipose-tissue triglyceride and diminished proinflammatory cytokines, prothrombotic factors and plasma NEFA 14 81 82. With reduced calorie intake, muscle insulin resistance declines; hepatic steatosis diminishes; dyslipidemia frequently disappears; and blood pressure falls.…”