Background: Few reports on the association of population-derived dietary patterns with excess body weight, using the approach of a systematic review currently exist.

Aim: The aim of the present systematic review was to identify dietary patterns associated with body mass index (BMI), body weight (BW)/BMI change, weight status and weight loss maintenance status.

Methods: Using MEDLINE (via PubMed) and EBSCO Host databases, we systematically reviewed studies from 1980 to 2020, which included men and women, aged ≥18 years. Primary outcome was BMI or the longitudinal change of individuals' BW or BMI, or weight status (normal weight/overweight/obesity) or weight loss maintenance status. We included observational studies, with or without a prospective design. Studies which met the inclusion criteria were evaluated based on the Newcastle-Ottawa Scale; only a posteriori dietary patterns were evaluated.

Results: Twenty-six studies were eligible for inclusion in the current analysis. The results indicate a relationship between adherence to a lacto-vegetarian dietary pattern, characterized by high intake of fruits, vegetables, whole grains, unprocessed cereals, dairy and low intake of high-fat foods and sweets, and longitudinal change of individuals' BW or BMI, or the risk of overweight/obesity.

Conclusions: Promotion of this healthy dietary pattern, as an alternative to focusing on specific nutrients or foods, may be a promising approach to be included in future long-term weight maintenance interventions.