Background Overweight/obesity are known risk factors for non-communicable diseases. Poor dietary quality is a major driver of overweight/obesity. Nigeria has limited evidence on the association of dietary quality with overweight/obesity using nationally representative data.

Methods We conducted a secondary analysis of the 2018 Nigeria Demographic and Health Survey, a cross-sectional survey monitoring the health of women (15-49 years) and under 5 children in Nigeria. Our study included 11,082 non-pregnant women aged ≥18 years who had data on body mass index (BMI) and a measure of dietary intake using a yes-or-no questionnaire of food groups for one day. Predictor variables comprised 7 indicators of diet quality: Minimum Dietary Diversity Score for Women (MDDW), representing micronutrient adequacy, and ALL-5, representing food group adequacy. Additionally, we considered the consumption of zero vegetable/fruit, animal-source foods (ASF), sugar-sweetened beverages (SSB), savoury/fried foods, and sweet foods. The dependent variable was overweight/obesity defined as BMI ≥25 kg/m². We examined the relationship between overweight/obesity and diet quality indicators using multivariable logistic regression, accounting for confounders: age, education, wealth, and smoking.

Results The prevalence of overweight/obesity was 31%, with a mean age of 31.5 (8.9 SD) years. 56% achieved the MDDW of five or more food groups, 77% did not meet ALL-5, indicating they were not eating the recommended food groups. 6% consumed zero-fruits/vegetables, and 21% did not consume at least one recommended animal-source food. 22% consumed SSB, 19% savoury/fried foods, and 15% sweet foods. In the fully adjusted regression models, women who consumed animal-source foods (OR 1.38, 95%-CI 1.20, 1.58) and SSB (OR 1.30; 95%-CI 1.14, 1.40) were at higher risk of having overweight/obesity compared to those who did not consume these foods. MDDW was not associated with overweight/obesity. ALL-5 showed a borderline inverse association (OR 1.05; 95% CI 1.00, 1.23). Additionally, zero fruit/vegetable consumption was associated with an increased risk of overweight/obesity among women with no formal education (OR 1.47; 95% CI 1.12, 2.04). In contrast, women who consumed sweet foods had a reduced risk of overweight/obesity if they were from the urban areas (OR 0.82; 95% CI 0.61, 0.99), the richest households (OR 0.78; 95% CI 0.64, 0.95), or southwest-Nigeria (OR 0.78; 95% CI 0.62, 0.98).

Conclusion Consumption of specific food groups (animal-source, SSB, zero-fruit/vegetable) is associated with overweight/obesity in Nigeria. However, the composite diet quality scores were not strongly associated with overweight/obesity. A more robust dietary assessment may give better insight into the specific dietary patterns linked to overweight/obesity.