Sustainable diets and risk of overweight and obesity: A systematic review and meta-analysis (2024)

Citation: Reger C, Leitzmann MF, Rohrmann S, Kühn T, Sedlmeier AM, Jochem C. Sustainable diets and risk of overweight and obesity: A systematic review and meta-analysis. Obesity Reviews. 2024;1‐11. doi:10.1111/obr.13707


Sustainable diets are gaining interest as a possible approach to tackle climate change and the global extent of obesity. Yet, the association between sustainable diets and adiposity remains unclear.

We performed a systematic review and meta-analysis, calculating summary relative risks and 95% confidence intervals (CI). We pooled maximally adjusted risk estimates, assessed heterogeneity and publication bias, calculated the E-value, and evaluated the risk of bias across the included studies.

A total of eight studies were eligible for analysis. Comparing the highest versus the lowest levels of adherence to sustainable diets, the pooled effect estimate was 0.69 (95% CI = 0.62–0.76) for overweight and 0.61 (95% CI = 0.47–0.78) for obesity.

These results suggest that sustainable diets may decrease the risk of overweight/ obesity and therefore could serve as enablers for improving both public and planetary health. An agreed-upon clear definition of sustainable diets would enhance the comparability of future studies in this area.

Key Notes extracted from the paper:

  • Of the 798 potential studies, after exclusion, 8 studies were eligible (four cohort and four cross-sectional studies) and were included in the systematic review and meta-analysis. Those studies yielded a total of 438,020 participants at baseline and ultimately 170,923 participants in the analytic sample. Six studies originated from Europe, one from North America, and one from South America.
  • Studies were considered eligible for inclusion if they (1) were observational studies, including cohort, case–control, or cross-sectional studies; (2) were carried out in generally healthy participants; (3) defined sustainable diets as exposure in a reasonable and reproducible way using a sustainability measure and considered BMI-defined overweight/obesity as the primary outcome; (4) provided a relative risk (RR) or odds ratio (OR) and 95% confidence intervals (CI) for the highest versus the lowest levels of sustainable diet/organic food consumption; (5) were published before November 23, 2023; and (6) were written in English language.
  • They use the definition by Willett et al. of sustainable diets being diets that promote health and well-being while reducing the environmental impact of food production and consumption. Besides mostly plant-based diets such as the Planetary Health Diet (PHD), organic food consumption meets several of the dimensions that characterize sustainable diets. Sustainable diets aim to ensure adequate nutrition of people worldwide while maintaining planetary boundaries and are thereby positively contributing to planetary health.
  • Sustainability itself lacks a universally agreed-upon definition. Therefore, every study included utilized a different method to classify sustainable diet, and organic agriculture was assumed to be sustainable, potentially resulting in high between-study heterogeneity. Although organic food consumption seems to be associated with more sustainable diets, the higher monetary costs of organic food is not in line with the Food and Agriculture Organization definition of sustainable diets. Furthermore, the sustainability of organic food can vary depending on factors such as location, crop type, and farming methods. Water and arable land requirements might even be higher than conventional farming methods.
  • To evaluate sustainability, studies used various indices or scores. The PHD Index assesses adherence to a reference diet proposed by the EAT-Lancet Commission. The Sustainability Diet Index is a score with a maximum of 20 points summed up using four subindices encompassing environmental, nutritional, economic, and sociocultural aspects. Kesse-Guyot et al. utilized an Organic Score ranging between 0 and 32 points across 18 food groups, and Andersen et al. used an overall organic food score ranging from 6 to 24 points.

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