Processed Meat Intake and Changes in Weight, Waist, Body Mass Index, and Fat Mass: Systematic Literature Review, Meta-Analysis, and GRADE Assessment of Cohort Studies of Adults.

Abstract

Context: Previous reviews have indicated that abstaining from processed meat may play a part in weight management; however, the certainty of these results has not been assessed systematically.

Objective: We sought to estimate the association between processed meat intake (including studies specifically mentioning "processed meat" and/or listing processed meat items and subsequent change in weight, waist circumference, body mass index (BMI), and fat mass among adults by summarizing evidence of cohort studies.

Data sources: A systematic literature search was performed in Embase and Medline via Ovid (including the Cochrane Database of Systematic Reviews) from inception to June 2024.

Data extraction: The data were extracted by 2 reviewers independently. The certainty in the estimates was assessed with the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) tool, and the risk of bias was assessed using the Cochrane's Risk of Bias in Nonrandomized Studies of Interventions (ROBINS-I) assessment tool.

Data analyses: The search resulted in a total of 2974 potential articles, of which 11 cohort studies (6 unique studies) were eligible for inclusion. Three studies (n = 381 291) were included in the random-effects model of measured body weight, resulting in a summary increase of 0.26 kg/y per 1 daily serving of processed meat (95% confidence interval [CI], 0.03-0.48; τ2: 0.03; I2: 92.95%). Four studies (n = 51 310) were included in the random-effects model of measured waist circumference, resulting in a summary increase of 0.14 cm/y per 1 daily serving of processed meat (95% CI, 0.02-0.26; τ2: 0.01; I2: 81.12%). The certainties of these estimates were low, due to serious risk of bias.

Conclusion: The analyses suggested a very weak association between increased processed meat intake and subsequent increase in measured weight, larger measured waist circumference, increase in self-reported BMI, and an increase in fat mass. However, due to methodological limitations the certainty of these results was low, and cautious interpretation of the results is warranted.

Systematic review registration: PROSPERO registration No. CRD42022335022.