INTERRELATIONSHIPS OF ACTIVITY AND DIETARY INTAKES OF ISOCALORIC DIETS CONTAINING DEFICIENT AND SURFEIT AMOUNTS OF PROTEIN WERE EXAMINED AND CORRELATED WITH CONCURRENT VARIATIONS IN GROWTH AND PHYSIOLOGY. DEVIANT RATIOS OF PROTEIN TO CARBOHYDRATE RESULTED IN LOW RATES OF GROWTH IN NONACTIVE CONTROL SS. LOW PROTEIN DIETS PRODUCED HIGH LEVELS OF ACTIVITY. ACTIVITY DID NOT AFFECT GROWTH RATES. HIGH PROTEIN DIETS PRODUCED LOW OR NORMAL LEVELS OF ACTIVITY, DEPENDING UPON ENVIRONMENT, AND RESULTED IN HIGH RATES OF GROWTH IN ACTIVE ANIMALS. MEASURES OF LIVER NUCLEIC AND FREE AMINO ACIDS SHOWED NO EFFECT OF ACTIVITY ON EFFECTS OF DIET. (PsycINFO Database Record (c) 2006 APA, all rights reserved)