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 .
Diets higher in dairy foods and dietary protein support bone health during diet- and exercise-induced weight loss in overweight and obese premenopausal women.
CONTEXT Consolidation and maintenance of peak bone mass in young adulthood may be compromised by inactivity , low dietary calcium , and diet-induced weight loss . OBJECTIVE We aim ed to determine whether higher intakes of dairy foods , dietary calcium , and protein during diet- and exercise-induced weight loss affected markers of bone health . PARTICIPANTS Participants included premenopausal overweight and obese women . DESIGN /INTERVENTION Ninety participants were r and omized into three groups ( n = 30 per group ) : high protein and high dairy ( HPHD ) , adequate protein and medium dairy ( APMD ) , and adequate protein and low dairy ( APLD ) , differing in dietary protein ( 30 , 15 , or 15 % of energy , respectively ) , dairy foods ( 15 , 7.5 , or < 2 % of energy from protein , respectively ) , and dietary calcium ( ∼1600 , ∼1000 , or < 500 mg/d , respectively ) . OUTCOME MEASURES Serum and urine bone turnover biomarkers , serum osteoprotegerin ( OPG ) , receptor activator of nuclear factor-κB lig and ( RANKL ) , PTH , 25-hydroxyvitamin D , leptin , and adiponectin measured at 0 and 16 wk . RESULTS All groups lost equivalent body weight ( P < 0.05 ) . N-telopeptide , C-telopeptide ( CTX ) , urinary deoxypyridinoline , and osteocalcin increased in APLD ( P < 0.01 ) , whereas in HPHD , osteocalcin and procollagen 1 amino-terminal propeptide ( P1NP ) increased ( P < 0.05 ) , and all resorption markers remained unchanged . P1NP to CTX and OPG to RANKL ratios increased in HPHD ( P < 0.005 ) , and P1NP to CTX ratio decreased in APLD ( P < 0.05 ) . PTH decreased in HPHD and APMD vs. APLD ( P < 0.005 ) , and 25-hydroxyvitamin D increased in HPHD ( P < 0.05 ) , remained unchanged in APMD , and decreased in APLD ( P < 0.05 ) . Leptin decreased and adiponectin increased in APMD and HPHD only ( P < 0.001 ) . CONCLUSIONS Hypoenergetic diets higher in dairy foods , dietary calcium , and protein with daily exercise , favorably affected important bone health biomarkers vs. diets with less of these bone-supporting nutrients
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 .