Obesity is a cardiovascular risk factor associated with endothelial dysfunction, but the effect of different weight loss strategies on endothelial function is not known.

Study Number: 43

Year: 2009

Study Design(COUNTRY 1=RCT 2= Systematic Review 3=Non-randomized controlled 4= single arm 5= post hoc analysis 6=Non-systematic review 7. Network meta-analysis 8=other 9 follow up to study): 1

Study background and AIM: "Obesity is a cardiovascular risk factor associated with endothelial dysfunction, but the effect of different weight loss strategies on endothelial function is not known. Aim: to measure, by brachial artery ﬂow-mediated dilation (FMD), the effect of diet on endothelial function in two hypocaloric diets, a very-low-carbohydrate diet and a Mediterranean diet."

6 Months or longer: N

Number of subjects and analysis: 20

Low-carb diet arm: "Atkins (A) diet Targets E: 20kcal/kg body weight Carb: 25g/d for 2 wks, then 10g/d increase weekly for duration of study Protein: 135g/d for 2 wks, then 110g/d for rest of the study Fat: NR Intake first 2 wks / end of study E: NR Carb: 5%E / 20%E Protein: 30%E / 25%E Fat: 65%E / 55%E"

Comparison diet ARM(S): "Mediterranean (M) diet Targets: NR Intake E: 20kcal/kg body weight Carb: 55%E Protein: 20%E, 80g/d Fat: 25%E"

Outcomes Studied: "Primary: FMD and other markers of endothelial function and oxidative stress/inflammation [interleukin-6 (IL-6), tumor necrosis factor (TNF), 8-iso-Prostaglandin F2a (8-isoPGF2a), adiponectin, glyceryltrinitrate (GTN)] Secondary: HOMA-IR, SBP, DBP, lipids, fasting and 2-hr glucose and insulin."

Result Summary: "Weight: both diets resulted in SS weight loss, but Atkins was SS BG. Endothelial function: on all measures, WG NSS both diets. BG NSS. Inflammation: on all measures, WG NSS both diets. BG NSS. Waist & hip size: both diets resulted in SS reductions. BG NSS. All lipids: WG NSS both diets, and BG NSS. Glucose control (HbA1c, FBG & 2-hr post-prandial): WG NSS both diets, and BG NSS. Fasting insulin: both diets resulted in SS improvement. BG NSS. 2-hr post-prandial insulin: Atkins SS favored."

FBG, Other Glucose Measures: "FBG & 2-hr post-prandial WG: N BG: N Med diet also WG NSS. BG NSS "

FBG WG Sign: 0

FBG BG Sign: 0

HbA1c: NR

HbA1c WG Sign: *

HbA1c BG Sign: *

Total C: "WG: N BG: N Med diet also WG NSS. BG NSS"

Total C WG Sign: 0

Total C BG: 0

HDL-C: "WG: N BG: N Med diet also WG NSS. BG NSS"

HDL-C WG Sig: 0

HDL-C BG Sig: 0

LDL-C: "WG: N BG: N Med diet also WG NSS. BG NSS"

LDL-C WG Sig: 0

LDL-C BG Sig: 0

TG: "WG: N BG: N Med diet also WG NSS. BG NSS"

TG WG Sig: 0

TG BG Sig: 0

TG/HDL-C ratio WG Sig: *

TG/HDL-C ratio BG Sig: *

Weight/bmi, Body Composition: "Weight WG: Y BG: Y Med diet also WG SS. Loss at 60 days Atkins: -7.6kg WG SS p<0.001 Med: -4.9kg WG SS p<0.001 BG SS p<0.014 Waist & hip size: both diets WG SS loss. BG NSS Body fat: WG NSS loss both diets. BG NSS"

Weight/BMI WG Sig: 1

Weight/BMI BG Sig: 1

SBP: "WG: Y BG: Y BG NSS Baseline→60days Atkins 124mmHg→117 WG SS p<0.005 Med diet WG NSS BG SS p<0.042"

SBP WG Sig: 1

SBP BG Sig: 1

DBP: "WG: N BG: N Med diet also WG NSS. BG NSS "

DBP WG Sig: 0

DBP BG Sig: 0

Fasting Insulin: "Fasting insulin WG: Y BG: N Med diet also WG SS. BG NSS Baseline→60days Atkins 22mUmL→18 WG SS p<0.005 Med 19mUmL→15 WG SS p<0.005 BG NSS 2-hr post-prandial WG: Y BG: N Med diet WG NSS BG NSS Baseline→60days Atkins 65mUmL→54 WG SS p<0.001 BG NSS "

Fasting Insulin WG SS: 1

Fasting Insulin BG SS: 0

Insulin Sensitivity/Resistance: "HOMA-IR WG: Y BG: N Med diet also WG SS. BG NSS Baseline→60days Atkins 5.62→4.09 WG SS p<0.005 Med 4.50→3.64 WG SS p<0.005 BG NSS"

Insulin Receptor Improvement WG sig: 1

Insulin Receptor Improvement BG sig: 0

Inflammation: "IL-6, TNF, 8-isoPGF2a WG: N BG: N Med diet also WG NSS. BG NSS"

CRP WG sig: *

CRP BG sig: 1

Diabetes Medication Use: NA

Safety Adverse Events: NR

Other: "Endothelial function FMD & GTN WG: N BG: N Med diet also WG NSS BG NSS Adiponectin WG: N BG: N Med diet also WG NSS. BG NSS"

Study Author's Conclusions: """As endothelial dysfunction is known to be associated with acute cardiovascular events, this study suggests that the cardiovascular risk might be increased in the ﬁrst days of a very-low-carbohydrate diet."" "

Abbreviations:

AHA - American Heart Association;

ALT - alanine aminotransferase;

AMDR - acceptable macronutrient distribution range;

AST - aspartate aminotransferase;

BG - between study groups;

BHOB - beta-hydroxybutyrate;

DBP - diastolic blood pressure;

E- energy, caloric intake;

eGFR - estimated glomerular filtration rate;

FBG - fasting blood glucose;

GGT - gamma-glutamyl transferase;

HDL-C - high-density lipoprotein cholesterol;

iGFR - isotope glomerurar filtration rate;

LDL-C - low-density lipoprotein cholesterol;

NAFLD - non-alcoholic fatty liver disease;

NR - not reported (or data needed for calculation not available);

N - no;

NA - not applicable;

NS - not specified;

NSS - not statistically significant;

SBP - systolic blood pressure;

SS - statistically significant;

TG - triglyceride;

total C - total cholesterol;

V - varied, mixed;

WG - within a study group;

WMD - weighted mean difference;

Y - yes

Number of People in Studies:

3,296 Enrolled in randomized controlled trials on 25% or less carbohydrates

2,626 Completed randomized controlled trials on 25% or less carbohydrates

79.67% 82% completion of studies

Duration of Trial

<6 Months

6-9 Months

1 -2 years

>2 years

Obesity is a cardiovascular risk factor associated with endothelial dysfunction, but the effect of different weight loss strategies on endothelial function is not known.

Abbreviations:

Number of People in Studies:

Duration of Trial

# of Trials

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