Effect of the glycemic index of the diet on weight loss, modulation of satiety, inflammation, and other metabolic risk factors: a randomized controlled trial.
BACKGROUND
Low-glycemic index (GI) diets have been proven to have beneficial effects in such chronic conditions as type 2 diabetes, ischemic heart disease, and some types of cancer, but the effect of low-GI diets on weight loss, satiety, and inflammation is still controversial.


OBJECTIVE
We assessed the efficacy of 2 moderate-carbohydrate diets and a low-fat diet with different GIs on weight loss and the modulation of satiety, inflammation, and other metabolic risk markers.


METHODS
The GLYNDIET study is a 6-mo randomized, parallel, controlled clinical trial conducted in 122 overweight and obese adults. Participants were randomly assigned to one of the following 3 isocaloric energy-restricted diets for 6 mo: 1) a moderate-carbohydrate and high-GI diet (HGI), 2) a moderate-carbohydrate and low-GI diet (LGI), and 3) a low-fat and high-GI diet (LF).


RESULTS
At weeks 16 and 20 and the end of the intervention, changes in body mass index (BMI; in kg/m(2)) differed significantly between intervention groups. Reductions in BMI were greater in the LGI group than in the LF group, whereas in the HGI group, reductions in BMI did not differ significantly from those in the other 2 groups (LGI: -2.45 ± 0.27; HGI: -2.30 ± 0.27; LF: -1.43 ± 0.27; F = 4.616, P = 0.012; pairwise comparisons: LGI compared with HGI, P = 1.000; LGI compared with LF, P = 0.016; HGI compared with LF, P = 0.061). The decrease in fasting insulin, homeostatic model assessment of insulin resistance, and homeostatic model assessment of β cell function was also significantly greater in the LGI group than in the LF group (P < 0.05). Despite this tendency for a greater improvement with a low-GI diet, the 3 intervention groups were not observed to have different effects on hunger, satiety, lipid profiles, or other inflammatory and metabolic risk markers.


CONCLUSIONS
A low-GI and energy-restricted diet containing moderate amounts of carbohydrates may be more effective than a high-GI and low-fat diet at reducing body weight and controlling glucose and insulin metabolism. This trial was registered at Current Controlled Trials (www.controlled-trials.com) as ISRCTN54971867.
From the Human Nutrition Unit, Faculty of Medicine and Health Sciences, Institut d'Investigació Sanitaria Pere Virgili, Universitat Rovira i Virgili, C/ Sant Llorenç, Reus, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, PH-A, RB, and MB); the Centros de Investigación Biomédica en Redobn Physiopathology of Obesity and Nutrition, Instituto de Salut Carlos III, Madrid, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, RB, and MB); and the Nutrition Unit, Internal Medicine Service, Hospital Universitari Sant Joan, Reus, Spain (AR-S).
Martí
M
Juanola-Falgarona
From the Human Nutrition Unit, Faculty of Medicine and Health Sciences, Institut d'Investigació Sanitaria Pere Virgili, Universitat Rovira i Virgili, C/ Sant Llorenç, Reus, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, PH-A, RB, and MB); the Centros de Investigación Biomédica en Redobn Physiopathology of Obesity and Nutrition, Instituto de Salut Carlos III, Madrid, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, RB, and MB); and the Nutrition Unit, Internal Medicine Service, Hospital Universitari Sant Joan, Reus, Spain (AR-S).
Jordi
J
Salas-Salvadó
From the Human Nutrition Unit, Faculty of Medicine and Health Sciences, Institut d'Investigació Sanitaria Pere Virgili, Universitat Rovira i Virgili, C/ Sant Llorenç, Reus, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, PH-A, RB, and MB); the Centros de Investigación Biomédica en Redobn Physiopathology of Obesity and Nutrition, Instituto de Salut Carlos III, Madrid, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, RB, and MB); and the Nutrition Unit, Internal Medicine Service, Hospital Universitari Sant Joan, Reus, Spain (AR-S).
Núria
N
Ibarrola-Jurado
From the Human Nutrition Unit, Faculty of Medicine and Health Sciences, Institut d'Investigació Sanitaria Pere Virgili, Universitat Rovira i Virgili, C/ Sant Llorenç, Reus, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, PH-A, RB, and MB); the Centros de Investigación Biomédica en Redobn Physiopathology of Obesity and Nutrition, Instituto de Salut Carlos III, Madrid, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, RB, and MB); and the Nutrition Unit, Internal Medicine Service, Hospital Universitari Sant Joan, Reus, Spain (AR-S).
Antoni
A
Rabassa-Soler
From the Human Nutrition Unit, Faculty of Medicine and Health Sciences, Institut d'Investigació Sanitaria Pere Virgili, Universitat Rovira i Virgili, C/ Sant Llorenç, Reus, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, PH-A, RB, and MB); the Centros de Investigación Biomédica en Redobn Physiopathology of Obesity and Nutrition, Instituto de Salut Carlos III, Madrid, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, RB, and MB); and the Nutrition Unit, Internal Medicine Service, Hospital Universitari Sant Joan, Reus, Spain (AR-S).
Andrés
A
Díaz-López
From the Human Nutrition Unit, Faculty of Medicine and Health Sciences, Institut d'Investigació Sanitaria Pere Virgili, Universitat Rovira i Virgili, C/ Sant Llorenç, Reus, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, PH-A, RB, and MB); the Centros de Investigación Biomédica en Redobn Physiopathology of Obesity and Nutrition, Instituto de Salut Carlos III, Madrid, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, RB, and MB); and the Nutrition Unit, Internal Medicine Service, Hospital Universitari Sant Joan, Reus, Spain (AR-S).
Marta
M
Guasch-Ferré
From the Human Nutrition Unit, Faculty of Medicine and Health Sciences, Institut d'Investigació Sanitaria Pere Virgili, Universitat Rovira i Virgili, C/ Sant Llorenç, Reus, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, PH-A, RB, and MB); the Centros de Investigación Biomédica en Redobn Physiopathology of Obesity and Nutrition, Instituto de Salut Carlos III, Madrid, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, RB, and MB); and the Nutrition Unit, Internal Medicine Service, Hospital Universitari Sant Joan, Reus, Spain (AR-S).
Pablo
P
Hernández-Alonso
From the Human Nutrition Unit, Faculty of Medicine and Health Sciences, Institut d'Investigació Sanitaria Pere Virgili, Universitat Rovira i Virgili, C/ Sant Llorenç, Reus, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, PH-A, RB, and MB); the Centros de Investigación Biomédica en Redobn Physiopathology of Obesity and Nutrition, Instituto de Salut Carlos III, Madrid, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, RB, and MB); and the Nutrition Unit, Internal Medicine Service, Hospital Universitari Sant Joan, Reus, Spain (AR-S).
Rafael
R
Balanza
From the Human Nutrition Unit, Faculty of Medicine and Health Sciences, Institut d'Investigació Sanitaria Pere Virgili, Universitat Rovira i Virgili, C/ Sant Llorenç, Reus, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, PH-A, RB, and MB); the Centros de Investigación Biomédica en Redobn Physiopathology of Obesity and Nutrition, Instituto de Salut Carlos III, Madrid, Spain (MJ-F, JS-S, NI-J, AD-L, MG-F, RB, and MB); and the Nutrition Unit, Internal Medicine Service, Hospital Universitari Sant Joan, Reus, Spain (AR-S).
Mònica
M
Bulló
D000328:Adult; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure; D015992:Body Mass Index; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D018752:Diet, Fat-Restricted; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D002149:Energy Intake; D005260:Female; D038321:Glycemic Index; D006801:Humans; D006815:Hunger; D007249:Inflammation / Q000178:diet therapy*; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D015596:Nutrition Assessment; D009765:Obesity / Q000178:diet therapy*; D050177:Overweight / Q000178:diet therapy*; D012307:Risk Factors; D012527:Satiation / Q000502:physiology; D015431:Weight Loss
D015415:Biomarkers; D001786:Blood Glucose; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D007328:Insulin