Long-term weight maintenance and cardiovascular risk factors are not different following weight loss on carbohydrate-restricted diets high in either monounsaturated fat or protein in obese hyperinsulinaemic men and women

The aim of this study was to determine after 52 weeks whether advice to follow a lower carbohydrate diet, either high in monounsaturated fat or low fat, high in protein had differential effects in a free-living community setting. Following weight loss on either a high monounsaturated fat, standard protein (HMF; 50% fat, 20% protein (67 g/d), 30% carbohydrate) or a high protein, moderate fat (HP) (40% protein (136 g/d), 30% fat, 30% carbohydrate) energy-restricted diet (6000 kJ/d) subjects were asked to maintain the same dietary pattern without intensive dietary counselling for the following 36 weeks. Overall weight loss was 6·2 (SD 7·3) kg (P<0·01 for time with no diet effect, 7·6 (SD 8·1) kg, HMF v. 4·8 (SD 6·6) kg, HP). In a multivariate regression model predictors of weight loss at the end of the study were sex, age and reported percentage energy from protein (R² 0·22, P<0·05 for the whole model). Fasting plasma insulin decreased (P<0·01, with no difference between diets), 13·9 (SD 4·6) to 10·2 (SD 5·2) mIU/l, but fasting plasma glucose was not reduced. Neither total cholesterol nor LDL-cholesterol were different but HDL was higher, 1·19 (SD 0·26) v. 1·04 (SD 0·29) (P<0·001 for time, no diet effect), while TAG was lower, 1·87 (SD 1·23) v. 2·22 (SD 1·15) mmol/l (P<0·05 for time, no diet effect). C-reactive protein decreased (3·97 (SD 2·84) to 2·43 (SD 2·29) mg/l, P<0·01). Food records showed that compliance to the prescribed dietary patterns was poor. After 1 year there remained a clinically significant weight loss and improvement in cardiovascular risk factors with no adverse effects of a high monounsaturated fat diet.