Lack of suppression of circulating free fatty acids and hypercholesterolemia during weight loss on a high-fat, low-carbohydrate diet.
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.


METHODS
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.
Hernandez
Teri L
TL
University of Colorado, Aurora, CO, USA. teri.hernandez@ucdenver.edu
Sutherland
Julie P
JP
Wolfe
Pamela
P
Allian-Sauer
Marybeth
M
Capell
Warren H
WH
Talley
Natalie D
ND
Wyatt
Holly R
HR
Foster
Gary D
GD
Hill
James O
JO
Eckel
Robert H
RH
D000328:Adult; D008078:Cholesterol, LDL / Q000097:blood; D050528:Diet, Carbohydrate-Restricted; D018752:Diet, Fat-Restricted; D004038:Diet, Reducing; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage / Q000009:adverse effects*; D002149:Energy Intake; D005230:Fatty Acids, Nonesterified / Q000097:blood*; D005260:Female; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood / Q000209:etiology*; D007328:Insulin / Q000097:blood; D008074:Lipoproteins / Q000097:blood; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000178:diet therapy*; D014280:Triglycerides / Q000097:blood; D015431:Weight Loss / Q000502:physiology*
D008078:Cholesterol, LDL; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D008074:Lipoproteins; D014280:Triglycerides