Lack of Suppression of Circulating Free Fatty Acids and Hypercholesterolemia During Weight Loss on a High-Fat, Low-Carbohydrate Diet

Am J Clin Nutr. 2010 Mar;91(3):578-85. doi: 10.3945/ajcn.2009.27909. Epub 2010 Jan 27.

Abstract

Background: Little is known about the comparative effect of weight-loss diets on metabolic profiles during dieting.

Objective: The purpose of this study was to compare the effect of a low-carbohydrate diet (< or =20 g/d) with a high-carbohydrate diet (55% of total energy intake) on fasting and hourly metabolic variables during active weight loss.

Design: Healthy, obese adults (n = 32; 22 women, 10 men) were randomly assigned to receive either a carbohydrate-restricted diet [High Fat; mean +/- SD body mass index (BMI; in kg/m(2)): 35.8 +/- 2.9] or a calorie-restricted, low-fat diet (High Carb; BMI: 36.7 +/- 4.6) for 6 wk. A 24-h in-patient feeding study was performed at baseline and after 6 wk. Glucose, insulin, free fatty acids (FFAs), and triglycerides were measured hourly during meals, at regimented times. Remnant lipoprotein cholesterol was measured every 4 h.

Results: Patients lost a similar amount of weight in both groups (P = 0.57). There was an absence of any diet treatment effect between groups on fasting triglycerides or on remnant lipoprotein cholesterol, which was the main outcome. Fasting insulin decreased (P = 0.03), and both fasting (P = 0.040) and 24-h FFAs (P < 0.0001) increased within the High Fat group. Twenty-four-hour insulin decreased (P < 0.05 for both groups). Fasting LDL cholesterol decreased in the High Carb group only (P = 0.003). In both groups, the differences in fasting and 24-h FFAs at 6 wk were significantly correlated with the change in LDL cholesterol (fasting FFA: r = 0.41, P = 0.02; 24-h FFA: r = 0.52, P = 0.002).

Conclusions: Weight loss was similar between diets, but only the high-fat diet increased LDL-cholesterol concentrations. This effect was related to the lack of suppression of both fasting and 24-h FFAs.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Cholesterol, LDL / blood
  • Diet, Carbohydrate-Restricted*
  • Diet, Fat-Restricted
  • Diet, Reducing
  • Dietary Carbohydrates / administration & dosage
  • Dietary Fats / administration & dosage
  • Dietary Fats / adverse effects*
  • Energy Intake
  • Fatty Acids, Nonesterified / blood*
  • Female
  • Humans
  • Hypercholesterolemia / blood
  • Hypercholesterolemia / etiology*
  • Insulin / blood
  • Lipoproteins / blood
  • Male
  • Middle Aged
  • Obesity / blood
  • Obesity / diet therapy*
  • Triglycerides / blood
  • Weight Loss / physiology*

Substances

  • Cholesterol, LDL
  • Dietary Carbohydrates
  • Dietary Fats
  • Fatty Acids, Nonesterified
  • Insulin
  • Lipoproteins
  • Triglycerides