The alteration of normal biological rhythms, also known as chronodisruption, may be associated with obesity development. For instance, those subject with preference for vespertinity seem to be prone to develop obesity. However, the current hypocaloric dietary treatment of obesity does not take into account these aspects. Therefore, the objective of this trial was to evaluate whether a diet adjusted to patient's chronotype is more effective that the current dietary recommendations. 209 subjects take part on a 3 month randomized, double-blind trial. 104 subjects followed a typical hypocaloric dietary treatment and the other 105 subjects undergone a diet with a daily caloric distribution adjusted to their chronotype. There were no sex or age differences between groups. Baseline characteristics were similar in both groups. Dropout rate was also similar in both interventions (p = 0.683). Although both groups improved their anthropometrical parameters, the chronotype-adjusted diet group achieved a statistically significant greater reduction in percentage of total body weight loss (%TWL), BMI and waist circumference than the control group (p < 0.010 in all contrasts). The effect on clinical parameters was less pronounced. This randomized trial has demonstrated for the first time that in overweight/obese subjects, a chronotype-adjusted diet is more effective than the traditional hypocaloric dietary treatment, at least regarding the anthropometrical parameters. Further research will confirm if this intervention is also more effective in the long term. NCT-ID: #NCT03755674, (available at: http://www.clinicaltrials.gov).