Seconda L, Egnell M, Julia C, Touvier M, Hercberg S, Pointereau P, et al. Association between sustainable dietary patterns and body weight, overweight, and obesity risk in the NutriNet-Santé prospective cohort. The American Journal of Clinical Nutrition. 2019;112(1):138-49
Dietitians-nutritionists working in community, clinical or food service settings.
This study investigated the associations between sustainable dietary patterns and overweight and obesity in French adults. It first calculated a Sustainable Diet Index (SDI) from information collected from 15,626 participants of the NutriNet-Santé study. It then compared weight gain over time and the risk of overweight and obesity using longitudinal data collected between 2014-2018 to this baseline information.
Bottom line for nutrition practice:
The results suggest that people who adopt highly sustainable dietary patterns sustainable diets may have a lower risk of weight gain, overweight, and obesity than those who do not adopt these behaviours. The results held true after multiple adjustments were made for demographic and lifestyle characteristics.
Improving the sustainability of current food systems may prevent future public health, environmental, and social concerns.
Our objective was to investigate the associations between sustainable dietary patterns, assessed using the Sustainable Diet Index (SDI), and the risk of obesity, overweight, and weight gain in French adults, with a prospective design.
In 2014, the SDI was computed among 15,626 participants of the NutriNet-Santé study (of whom 76% were women) using data collected within the BioNutriNet project. The SDI ranges from 4 (lowest sustainability) to 20 points and includes 4 subindexes representing the 4 pillars of a sustainable diet. Longitudinal data of weight and height were collected yearly from 2014 to 2018. We used mixed models to estimate the associations between sex-specific quintiles (Qs) of the SDI and weight change and Cox proportional hazard models with different levels of adjustments to assess the association between sex-specific Qs of the SDI and risk of obesity and overweight (mean follow-up time: 2.8 y).
At baseline, a higher percentage of participants with overweight was observed in the first SDI Q, reflecting the lowest sustainable dietary patterns (Q1), than in Q5 (29.83% compared with 12.71%). Compared with Q5, a slight increase (at the population level) of almost 160 g/y was observed in Q1, whereas weight remained relatively stable among participants in other Qs. In total, 281 incident cases of obesity and 777 cases of overweight were identified during the follow-up. Participants in Q1 had a higher risk of obesity and overweight than participants in Q5 (HR comparing Q1 with Q5: 4.03; 95% CI: 2.42, 6.10; P-trend < 0.001; and HR comparing Q1 with Q5: 1.49; 95% CI: 1.13, 1.95; P-trend < 0.001, respectively).
The findings support a potential protective role for more sustainable diets to prevent the risk of weight gain, overweight, and obesity. This trial was registered at clinicaltrials.gov as NCT03335644.
Details of results:
A Sustainable Diet Index (SDI) was developed for the study and used 7 indicators categorized into 4 sub-indexes: i) environmental (land occupation, greenhouse gas emissions, primary energy consumption);
ii) nutritional difference between energy need and intake in absolute terms, probability of adequate nutrient intake, contribution of organic food to diet), ii) economic (proportion of income devoted to diet), and iv) sociocultural (food practices such as place of food purchase, and ready-made products – the latter acting as a proxy of cooking practices). Sociodemographic and lifestyle data were also collected.
Participant results were divided into 5 equal categories (quintiles). Overall, participants having the lowest SDI had a higher risk of obesity and overweight than participants having the highest SDI. At the baseline (beginning of the study), participants with the lowest SDI score had 29.83% overweight compared with 12.71% of participants in the quintile with the highest SDI. At the end of the study, the quintile with the lowest SDI had a small but statistically significant weight gain (160g per year) compared to the quintile with the highest SDI. Weight stayed relatively stable among the participants in the other quintiles. As expected, sociodemographic and lifestyle characteristics differed across the categories (e.g., higher education, income and activity were associated with the quintile having the highest SDI). However, the researchers reported that even after multiple adjustments were made for demographic and lifestyle characteristics, the associations still remained significant. Therefore, the researchers suggest that the results support a potential protective role for sustainable diets in preventing the risk of weight gain, overweight, and obesity.
The authors list possible reasons for these associations, including: a higher energy intake in the lowest SDI quintile and a higher consumption of fruit and vegetables in the high SDI quintile. They also refer to the larger body of literature showing that that higher quality of diets are associated with lower potential weight gain and obesity; higher energy density of meat products or increased concentrations of some nutrients such as saturated fatty acids or cholesterol may be involved in weight outcomes; and, food production methods or processes such as cooking practices or consumption of organic foods may be a factor in weight maintenance (regarding the latter, literature discusses the exposure to synthetic pesticides and in particular endocrine disruptors may be a risk for obesity).
Of additional interest:
While these results might be expected in any dietary pattern which focuses on improving dietary quality, the researchers note that – to their knowledge – this is the first study to quantitatively estimate these associations using a validated, multidisciplinary index.
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