Adverse gastrointestinal events were more common with high-protein diets .
Multivariable meta-regression analysis showed no significant dose response with higher protein intake .
Conclusions : Higher-protein diets  probably improve adiposity , blood pressure and triglyceride levels , but these effects are small and need to be weighed against the potential for harms
Background / Objectives : Numerous r and omised controlled trials ( RCTs ) published in first tier medical journals have evaluated the health effects of diets high in protein .
We conducted a rigorous systematic review of RCTs comparing higher- and lower-protein diets .
Effect of normal-fat diets, either medium or high in protein, on body weight in overweight subjects: a randomised 1-year trial
BACKGROUND : We have previously reported that a fat-reduced high-protein diet had more favourable effects on body weight loss over 6 months than a medium-protein diet . OBJECTIVE : To extend this observation by a further 6–12 months less stringent intervention and a 24 months follow-up . DESIGN : A r and omised 6 months strictly controlled dietary intervention followed by 6–12 months dietary counselling period , and a subsequent 24 months follow-up , comparing an ad libitum , fat-reduced diet ( 30 % of energy ) either high in protein ( 25 % of energy , HP ) or medium in protein ( 12 % of energy , MP).SUBJECTS : A total of 50 overweight and obese subjects ( age : 19–55 y ; BMI : 26–34 kg/m2 ) . MEASUREMENTS : Change in body weight , body composition and blood parameters . RESULTS : After 6 months , the HP group ( n=23 ) achieved a greater weight loss than the MP group ( n=23 ) ( 9.4 vs 5.9 kg ) ( P<0.01 ) . After 12 months , 8 % had dropped out in the HP vs 28 % in the MP group ( P<0.07 ) . After 12 months , the weight loss was not significantly greater among the subjects in the HP group ( 6.2 and 4.3 kg ) , but they had a 10 % greater reduction in intra-abdominal adipose tissue and more in the HP group ( 17 % ) lost > 10 kg than in the MP ( P<0.09 ) . At 24 months , both groups tended to maintain their 12 months weight loss , but more than 50 % were lost to follow-up . CONCLUSION : A fat-reduced diet high in protein seems to enhance weight loss and provide a better long-term maintenance of reduced intra-abdominal fat stores
Adverse gastrointestinal events were more common with high-protein diets .
Multivariable meta-regression analysis showed no significant dose response with higher protein intake .
Conclusions : Higher-protein diets  probably improve adiposity , blood pressure and triglyceride levels , but these effects are small and need to be weighed against the potential for harms
Background / Objectives : Numerous r and omised controlled trials ( RCTs ) published in first tier medical journals have evaluated the health effects of diets high in protein .
We conducted a rigorous systematic review of RCTs comparing higher- and lower-protein diets .