Low-fat hypocaloric (LF) diets reduce insulin resistance and prevent T2D.

Study Number: 46

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: "Low-fat hypocaloric (LF) diets reduce insulin resistance and prevent T2D. Low-carbohydrate, high-fat (LC) diets are advocated as an alternative, but reciprocal increases in dietary fat may have detrimental effects on insulin resistance and offset the beneﬁts of weight reduction. Aim: to investigate the effects of a LF diet vs a LC diet."

6 Months or longer: N

Number of subjects and analysis: 24

Low-carb diet arm: "Targets E: 7.9MJ/d (`1887kcal/d) Carb: 20%E Protein: 20%E Fat: 60%E Intake: same as above"

Comparison diet ARM(S): "Targets E: 7.1MJ/d (`1696kcal/d) Carb: 60%E Protein: 20%E Fat: 20%E Intake: same as above"

Outcomes Studied: "Primary: insulin resistance (by glucose infusion rate [GIR] during euglycemic clamp) Secondary: body composition, meal tolerance–related insulin secretion, vascular compliance, plasma leptin, and retinol-binding protein 4 (RBP4)."

Result Summary: "Weight and all other measures of body composition, GIR, HbA1c, SBP, DBP, fasting insulin and TG all improved SS in both groups. TG SS improved only in the LC diet; BG SS different. HDL-c worsened in both diets but SS so only in LF diet. Total C and arterial stiffness SS better only in LF diet."

FBG, Other Glucose Measures: "FBG WG: N BG: N BG NSS GIR WG: Y BG: N SS improved only in LC diet GIR Baseline→8 wks LC diet 23.5→28.3 p=0.02 LF diet 28.3→30.2 WG NSS BG NSS"

FBG WG Sign: 0

FBG BG Sign: 0

HbA1c: "WG: Y BG: N Baseline→8 wks LC diet 5.3%→5.2 p<0.01 LF diet WG NSS"

HbA1c WG Sign: 1

HbA1c BG Sign: 0

Total C: "WG: N BG: N Improved in both; SS only in LF diet group. Baseline→8 wks LC diet 4.65mmol/L→4.05 WG NSS LF diet 5.0mmol/L→4.12 WG p<0.01 BG NSS"

Total C WG Sign: 0

Total C BG: 0

HDL-C: "WG: N BG: N Worsened in both diet groups but SS only in LF diet. Baseline→8 wks LC diet 1.47mmol/L→1.35 WG NSS LF diet 1.40mmol/L→1.15 WG p<0.01 BG NSS"

HDL-C WG Sig: 0

HDL-C BG Sig: 0

LDL-C: "WG: N BG: N Improved in both diet groups but SS only in LF diet. Baseline→8 wks LC diet 2.46mmol/L→2.1 WG NSS p=0.05 LF diet 2.85mmol/L→2.41 WG p<0.01 BG NSS"

LDL-C WG Sig: 0

LDL-C BG Sig: 0

TG: "WG: Y BG: Y Improved in both diet groups but SS only in LC diet. Baseline→8 wks LC diet 1.59mmol/L→0.91 WG NSS p<0.01 LF diet 1.55mmol/L→1.43 WG NSS BG SS p=0.01"

TG WG Sig: 1

TG BG Sig: 1

TG/HDL-C ratio WG Sig: *

TG/HDL-C ratio BG Sig: *

Weight/bmi, Body Composition: "Weight, BMI, waist size, fat and lean mass, %body fat, all WG: Y BG: N All improved SS in both diet groups. Weight Baseline→8 wks LC diet 97.7kg→90.3 WG SS p<0.01 LF diet 91.5→85.0 WG SS p<0.01 BG NSS BMI Baseline→8 wks LC diet 34.5→31.9 WG SS p<0.01 LF diet 32.8→30.5 WG SS p<0.01 BG NSS "

Weight/BMI WG Sig: 1

Weight/BMI BG Sig: 0

SBP: "WG: Y BG: N Improved SS both groups Baseline→8 wks LC diet 122mmHg→114 WG SS p<0.01 LF diet 127mmHg→119 WG SS p=0.03 BG NSS"

SBP WG Sig: 1

SBP BG Sig: 0

DBP: "WG: Y BG: N Improved SS both groups Baseline→8 wks LC diet 70mmHg→65 WG SS p=0.03 LF diet 77mmHg→71 WG SS p<0.01 BG NSS"

DBP WG Sig: 1

DBP BG Sig: 0

Fasting Insulin: "WG: Y BG: N Improved SS in both diet groups. Baseline→8 wks LC diet 12.5mU/I→7.4 WG NSS p<0.01 LF diet 11.4mU/I→9.0 WG SS p=0.02 BG NSS "

Fasting Insulin WG SS: 1

Fasting Insulin BG SS: 0

Insulin Sensitivity/Resistance: "Insulin secretion after meal tolerance test WG: Y BG: N SS improved only in LC diet"

Insulin Receptor Improvement WG sig: 1

Insulin Receptor Improvement BG sig: 0

Inflammation: NR

CRP WG sig: *

CRP BG sig: *

Diabetes Medication Use: NA

Safety Adverse Events: NR

Other: "Systemic arterial stiffness WG: N BG: N Improved in both groups but SS only in LF group. BG NSS Leptin WG: Y BG: N decreased SS both groups RBP4 WG: Y BG: N Decreased SS both groups BG NSS"

Study Author's Conclusions: "This study demonstrates comparable effects on insulin resistance of LF and LC diets independent of macronutrient content.The difference in augmentation index [arterial stiffness] may imply a negative effect of LC diets on vascular risk."

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

Low-fat hypocaloric (LF) diets reduce insulin resistance and prevent T2D.

Abbreviations:

Number of People in Studies:

Duration of Trial

# of Trials

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