To determine the effects of diets varying in carb-to-fat ratio on total energy expenditure
"Run-in phase: E - 60% of estimated need Carb - 45%E Protein - 25%E Fat - 30%E Test diet phase: All 3 test diet groups: E - adjusted periodically to stabilize weight (~2000kcal/d) Protein - 20%E Moderate-carb diet: Carb - 40%E Fat - 40%E Low-carb diet: Carb - 20%E Fat - 60%E Intake: Moderate-carb diet: E: 2001kcal/d Carb - 39.7%E (205g/d) Fat - 40.1%E (92g/d) Low-carb diet: E: 2001kcal/d Carb - 20.3%E (105g/d) Fat - 59.6%E (137g/d) "
"High-carb diet Targets E - adjusted periodically to stabilize weight (~2000kcal/d) Carb - 60%E Protein - 20%E Fat - 20%E Intake E: 2001kcal/d Carb: 59.2%E, 305g/d Protein: 19.9%E, 102g/d Fat: 20.9%E, 48g/d "
"Primary outcome: total E expenditure (E Ex) per carb level (average during test phase - test phase baseline estimate). Secondary outcomes: Resting E EX, physical activity, skeletal muscle work efficiency, ghrelin, and leptin; insulin and glucose levels, to test for effect modification associated with carbohydrate-insulin model. Results are reported for both intention-to-treat analysis (n=162) and for completers (n=120). Some results reported here are for completers only. Trend estimates for each variable are provided. This is the estimate of change per 10% decrease in daily carb intake, "
"Change in total E Ex, per carb intake level, for completers: High carb: -102kcal/d Moderate car: +29cal/d Low carb: +176cal/d BG SS, p<0.001. (Similar results for intention-to-treat cohort. SS BG p=0.002) Trend estimate: +52kcal difference per 10% change in daily carb intake. Resting E Ex, skeletal muscle work efficiency were BG NSS for both the intention-to-treat and completer cohorts. Ghrelin - declined SS with low-carb diet, and more so as carb level declined. SS BG for both intention-to-treat and completer cohorts, p=0.02. Leptin - increased at all 3 carb levels, more so as carb level increased. NSS BG. "
40 adverse events reported for 36 subjects, two serious (one of which may have been related to intervention). After randomization, 13 subjects had an adverse event; this number did not differ by diet group.
"120 of 164 completed study. LC diet: 54/57 retained (94.7%) Moderate carb diet: 48/53 retained (90.1%) High carb diet: 46/54 retained (85.2%) Those withdrawing due to diet not reported."
"Effects on insulin and glucose on total E Ex per diet compositon group Fasting insulin - among those with highest insulin levels, the difference in E Ex between the high-carb group and the low-carb group was 308kcal/d (p=0.004) in the intention-to-treat analysis and 478kcal/d (p<0.001) for the completer cohort analysis. Similar effects though less pronounced were observed for fasting glucose, insulin concentration, and insulin resistance."
"""Consistent with the carbohydrate-insulin model, lowering dietary carbohydrate increased energy expenditure during weight loss maintenance."" This metabolic effect may improve the success of obesity treatment, especially among those with high insulin secretion. Individual levels of insulin secretion appears to affect response to carbohydrate in the diet. ""...dietary quality can affect energy expenditure independently of body weight, a phenomenon that could be key to obesity treatment..."" ""Additional research is warranted for"": - effects of glycemic load on body weight - effects of glycemic index on carb intake - effects of insulin secretion and other biological factors - efficacy of extreme carbohydrate restriction (ketogenic diet) for treating obesity or diabetes"
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
1 -2 years
# of Trials
Join the Low-Carb Action Network to stay informed of our latest news and calls to action.
Don't miss out on the chance to lend your voice for change!