Improving diet quality over nine-years is associated with less weight gain in mid-age Australian women: a cohort study

Background and aims: Most studies measure baseline diet quality exclusively and hence the impact of longitudinal changes in dietary intake in relation to weight change is not considered. Therefore, this study aimed to examine whether change in diet quality over nine-years was associated with weight change over the same period in mid-age Australian women. Methods and results: Healthy mid-age (45-49 years) women from the Australian Longitudinal study on Women's Health (ALSWH) were eligible a valid total energy intake (TEI) was reported at baseline (n = 2381), determined using Goldberg cut-offs. Diet quality was measured by the Australian Recommended Food Score (ARFS) using data derived from a validated food frequency questionnaire. Multiple linear regressions were used to evaluate relationships between change in diet quality and weight in mid-age women (n = 1999). Women in the highest tertile of ARFS change improved diet quality [mean ± SD] [7 ± 4 points], while those in the lowest [-9 ±5 points] and middle [-1±2 points] tertiles had worse diet quality at follow-up. Overall, mean weight gain was 2.3 ± 7.2 kg over nine years. Those in the highest tertile of ARFS change gained significantly less weight, compared to the lowest tertile; ß = -1.2 kg [95% CI: -2.31, -0.11; p = 0.03] after adjustment for changes in confounders and baseline weight, baseline ARFS, and total energy intake. Conclusions: Improving diet quality could be an important strategy for promoting modest weight loss and potentially contribute to preventing weight gain in mid-age women, which is important for metabolic health.