This study has limitations. The feeding periods were too brief to observe dietary effects on clinical events. Furthermore, the study did not include patients with diabetes or CKD, populations that might demonstrate greater changes in kidney function from alterations in dietary carbohydrates. Moreover, the diets were all DASH-like, healthful diets. It is possible that greater effects on kidney function would be observed if the reference diet was a typical American diet. Finally, it should be noted that by design reductions in %carb intake were coupled with increases in both fat and protein to keep overall caloric intake constant between diets. Thus, it would be inaccurate to conclude that reducing %carb alone increased kidney function. A better interpretation would be that replacing calories from carbohydrates with calories from protein and fat increased kidney function.