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 protein intake on bone mineralization during weight loss: a 6-month trial.
OBJECTIVE The long-term effect of dietary protein on bone mineralization is not well understood . RESEARCH METHODS AND PROCEDURES Sixty-five overweight ( body mass index , 25 to 29.9 kg/m(2 ) ) or obese ( > or = 30 kg/m(2 ) ) subjects were enrolled in a r and omized , placebo-controlled , 6-month dietary-intervention study comparing two controlled ad libitum diets with matched fat contents : high protein ( HP ) or low protein ( LP ) . Body composition was assessed by DXA . RESULTS In the HP group , dietary-protein intake increased from 91.4 g/d to a 6-month intervention mean of 107.8 g/d ( p < 0.05 ) and decreased in the LP group from 91.1 g/d to 70.4 g/d ( p < 0.05 ) . Total weight loss after 6 months was 8.9 kg in the HP group , 5.1 kg in the LP group , and none in the control group . After 6 months , bone mineral content ( BMC ) had declined by 111 + /- 13 g ( 4 % ) in the HP group and by 85 + /- 13 g ( 3 % ) in the LP group ( not significant ) . Loss of BMC was more positively correlated with loss of body fat mass ( r = 0.83 ; p < 0.0001 ) than with loss of body weight . Six-month BMC loss , adjusted for differences in fat loss , was greater in the LP group than in the HP group [ difference in LP vs. HP , 44.8 g ( 95 % confidence interval , 16 to 73.8 g ) ; p < 0.05 ] . Independent of change in body weight and composition during the intervention , highprotein intake was associated with a diminished loss of BMC ( p < 0.01 ) . DISCUSSION Body-fat loss was the major determinant of loss of BMC , and we found no adverse effects of 6 months of high-protein intake on BMC
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 .