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 .
Protein intake, weight loss, and bone mineral density in postmenopausal women.
BACKGROUND Higher protein diets are promoted for effective weight loss . Striated tissues in omnivorous diets contain high- quality protein , but limited data exist regarding their effects on bone . METHODS To examine the effects of energy restriction-induced weight loss with higher protein omnivorous diets versus lower protein vegetarian diets on  bone mineral density  in overweight postmenopausal women , two r and omized controlled feeding studies were conducted . In Study 1 , 28 women consumed 750 kcal/day energy deficit diets with 18 % energy from protein via lacto-ovo vegetarian sources ( normal protein , n = 15 ) or 30 % energy from protein with 40 % of protein from lean pork ( higher protein , n = 13 , omnivorous ) for 12 weeks . In Study 2 , 54 women consumed their habitual diet ( control , n = 11 ) or 1,250 kcal/day diets with 16 % energy from nonmeat protein sources ( n = 14 ) or 26 % energy from protein , including chicken ( n = 15 ) or beef ( n = 14 ) for 9 weeks . RESULTS Study 1 : With weight loss ( normal protein -11.2 % , higher protein -10.1 % ) , bone mineral density was not significantly changed in normal protein ( -0.003 ± 0.003 g/cm(2 ) , -0.3 % ) but decreased in higher protein ( -0.0167 ± 0.004 g/cm(2 ) , -1 . 4 % , group-by-time p < .05 ) . Study 2 : The control , nonmeat , chicken , and beef groups lost 1.5 % , 7.7 % , 10.4 % , and 8.1 % weight and 0.0 % , 0.4 % , 1.1 % , and 1.4 % bone mineral density , respectively . The change of bone mineral density was significant for chicken and beef compared with the control ( group-by-time , p < .05 ) . Markers of calcium metabolism and bone homeostasis in blood and urine were not changed over time or differentially affected by diet . CONCLUSION Consumption of higher protein omnivorous diets promoted decreased bone mineral density after weight loss in overweight postmenopausal women
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 .