To test two competing models of the role of carbohydrate in energy expenditure (EE) – carbohydrate-insulin model (that a carb-rich diet results in body storing carb as fat) vs “a calorie is a calorie” (that diet maconutrient variation does not affect EE or body fat); to investigate whether an isocaloric low-carbohydrate ketogenic diet (KD) is associated with changes in EE, respiratory quotient (RQ), and body composition
5
2016
1
To test two competing models of the role of carbohydrate in energy expenditure (EE) - carbohydrate-insulin model (that a carb-rich diet results in body storing carb as fat) vs "a calorie is a calorie" (that diet maconutrient variation does not affect EE or body fat); to investigate whether an isocaloric low-carbohydrate ketogenic diet (KD) is associated with changes in EE, respiratory quotient (RQ), and body composition
N
17
"Targets E: 2394kcal/d Carb: <31g/d; 5%E Protein: 91g/d; 15%E Fat: 212g/d; 80%E Intake E: 2738kcal/d Carb: <35.8g/d; 5.2%E Protein: 104g/d Fat: 242g/d; 79.5%E "
"Baseline run-in diet Targets E: 2398kcal/d Carb: 300g/d; 50%E Protein: 91g/d; 15%E Fat: 93g/d; 35%E Intake E: 2739kcal/d Carb: 338g/d Protein: 104g/d Fat: 108g/d"
"Primary: energy expenditure (EE), respiratory quotient (RQ), and body composition. Secondary: urinary measures including fasting and daily insulin secretion (C-peptide), urea, ketones, nitrogen, creatinine; metabolite and hormone concentrations including fatty acids, glucose, triglycerides, glucagon, leptin."
"WG: NR BG: N BG NSS"
*
0
NR
*
*
NR
*
*
NR
*
*
NR
*
*
"WG: NR BG: Y K diet: 85.4mg/dL B diet: 104 p=0.01"
*
1
*
*
"Weight WG: NR BG: Y Baseline diet period: -0.8kg of body weight during the last 15 days of the baseline diet period, which indicated a negative E balance of 373kcal/d. K diet period: -2.2kg, indicating a 243kcal/d negative E balance (BG NSS difference for E balance) p<0.0001 Body fat: 0.3 kg loss during B diet phase and 0.5kg loss during K diet. ""body fat loss slowed during the ketogenic diet phase and coincided with increased protein utilization and loss of fat-free mass."" "
*
1
NR
*
*
NR
*
*
"WG: NR BG: Y K diet: 6.27mU/mL B diet: 7.92 p=0.0039 C-peptide WG: NR BG: Y K diet: 1.15ng/mL B diet: 1.47 p<0.0001"
*
1
NR
*
*
NR
*
*
NA
NR
"EE WG: NR BG: Y K diet: 2676kcal/d B diet: 2619 p<0.0004 SEE K diet: 1658kcal/d B diet: 1569 p<0.0001"
"The isocaloric K diet was not accompanied by increased body fat loss but was associated with relatively small increases in EE that were near the limits of detection with the use of state-of-the-art technology."
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
# of Trials
36
6
9s
1