To understand the psychological antecedents or personal factors that lead to weight control behaviours that can help to develop more effective prevention strategies.

The present correlational study has a non-experimental, quantitative, cross-sectional design. A model was tested considering types of motivation (autonomous motivation, controlled motivation and amotivation) as mediators in the relationship between the Grit personality and healthy and unhealthy weight control behaviours, with self-control as a moderator in the aforementioned indirect effects.

Monterrey (Nuevo León, México).

A representative sample of 1219 adults (men = 599; women = 620) aged 18–65 years (M = 29·37, sd = 11·83).

Findings supported the mediator role of the types of motivation. Specifically, Grit showed a positive indirect effect on healthy weight control behaviours through autonomous motivation. Conversely, Grit showed a negative indirect effect on unhealthy weight control behaviours through autonomous motivation. Furthermore, findings supported the moderator role of self-control in the relationship between amotivation and healthy and unhealthy weight control behaviours.

This study provides evidence for the key role of Grit in the adoption of healthy or unhealthy control behaviours, as well as the role of autonomous motivation in the development of healthy behaviours.