Body weight, BMI, and chest circumference (mean ± SEM) of control and snack-fed male subadult common marmosets. No differences were found between groups, and all marmosets showed significant (F = 12.7, P = 0.005, n = 12) increases in weight during months 2 and 3 of the treatment. BMI did not differ significantly between the 2 groups, but chest circumference was significantly (U6,6 = 4.0, P = 0.03) increased in control compared with snack-fed marmosets.