Physical exercise has been shown to improve dysmetabolism in older adults, reducing cardiovascular risk, while its role in preventing dysmetabolism is less known. Moreover, most of the trials use exercise programs that are difficult to put into daily practice. The purpose of this Randomized Controlled Trial (RCT) was to evaluate the effectiveness of a 3-month moderate exercise program in improving or preventing dysmetabolism in 120 older adults, randomly selected for the exercise program (experimental group) or cultural activities (control group). None of the subjects were following a hypocaloric diet, and all of them reported healthy eating habits. Anthropometric (Body Mass Index (BMI) and Waist Circumference (WC)) and metabolic variables (fasting plasma glucose (FPG), High-Density Lipoprotein Cholesterol (HDL-C), and triglycerides (TG)) were assessed at baseline (T0) and at the end of the trial (T1). Dysmetabolism was defined by the presence of an increased WC plus at least two metabolic alterations. At T0, the two groups did not differ by sex, age, education, BMI, WC, FPG, HDL-C levels, and prevalence of dysmetabolism. The mean BMI value indicated overweight, and WC values were higher than the cut-off. At T1, a slight reduction in the number of people with dysmetabolism was found only in the experimental group. However, none of the individuals without dysmetabolism at T0 in the experimental group developed it at T1, while 11.4% developed it in the control group (p = 0.032). This study highlights that a moderate exercise program, accessible in daily practice, can prevent dysmetabolism in older adults, even while being overweight, while if dysmetabolism is already present, more prolonged combined nutritional and exercise interventions will be needed.