Conclusions Large r and omized controlled trials of at least 6 months duration with carbohydrate restriction appear superior in improving lipid markers when compared with low-fat diets .
Context Carbohydrate-restricted diets may increase low-density lipoprotein cholesterol and thereby cardiovascular risk .
Objective A systematic review and meta-analyses were conducted to compare the effects of very low , low , and moderate carbohydrate , higher fat diets versus high-carbohydrate , low-fat diets on low-density lipoprotein cholesterol and other lipid markers in overweight/obese adults .
Very low-carbohydrate and low-fat diets affect fasting lipids and postprandial lipemia differently in overweight men.
Hypoenergetic very low-carbohydrate and low-fat diets are both commonly used for short-term weight loss ; however , few studies have directly compared their effect on blood lipids , with no studies to our knowledge comparing postpr and ial lipemia , an important independently identified cardiovascular risk factor . The primary purpose of this study was to compare the effects of a very low-carbohydrate and a low-fat diet on fasting blood lipids and postpr and ial lipemia in overweight men . In a balanced , r and omized , crossover design , overweight men ( n = 15 ; body fat > 25 % ; BMI , 34 kg/m(2 ) ) consumed 2 experimental diets for 2 consecutive 6-wk periods . One was a very low-carbohydrate ( < 10 % energy as carbohydrate ) diet and the other a low-fat ( < 30 % energy as fat ) diet . Blood was drawn from fasting subjects on separate days and an oral fat tolerance test was performed at baseline , after the very low-carbohydrate diet period , and after the low-fat diet period . Both diets had the same effect on serum total cholesterol , serum insulin , and homeostasis model analysis -insulin resistance ( HOMA-IR ) . Neither diet affected serum HDL cholesterol ( HDL-C ) or oxidized LDL ( oxLDL ) concentrations . Serum LDL cholesterol ( LDL-C ) was reduced ( P < 0.05 ) only by the low-fat diet ( -18 % ) . Fasting serum triacylglycerol ( TAG ) , the TAG/HDL-C ratio , and glucose were significantly reduced only by the very low-carbohydrate diet ( -44 , -42 , and -6 % , respectively ) . Postpr and ial lipemia was significantly reduced when the men consumed both diets compared with baseline , but the reduction was significantly greater after intake of the very low-carbohydrate diet .  Mean and peak LDL particle size increased only after the very low-carbohydrate diet . The short-term hypoenergetic low-fat diet was more effective at lowering serum LDL-C , but the very low-carbohydrate diet was more effective at improving characteristics of the metabolic syndrome as shown by a decrease in fasting serum TAG , the TAG/HDL-C ratio , postpr and ial lipemia , serum glucose , an increase in LDL particle size , and also greater weight loss ( P < 0.05 )
Conclusions Large r and omized controlled trials of at least 6 months duration with carbohydrate restriction appear superior in improving lipid markers when compared with low-fat diets .
Context Carbohydrate-restricted diets may increase low-density lipoprotein cholesterol and thereby cardiovascular risk .
Objective A systematic review and meta-analyses were conducted to compare the effects of very low , low , and moderate carbohydrate , higher fat diets versus high-carbohydrate , low-fat diets on low-density lipoprotein cholesterol and other lipid markers in overweight/obese adults .