Description of Weight-Related Content and Recommended Dietary Behaviors for Weight Loss Frequently Reposted on X (Twitter) in English and Japanese: Content Analysis.

Background: Both obesity and underweight are matters of global concern. Weight-related content frequently shared on social media can reflect public recognition and affect users' behaviors and perceptions. Although X (Twitter) is a popular social media platform, few studies have revealed the content of weight-related posts or details of dietary behaviors for weight loss shared on X.

Objective: This study aims to describe body weight-related content frequently reposted on X, with a particular focus on dietary behaviors for weight loss, in English and Japanese.

Methods: We collected English and Japanese X posts related to human body weight having over 100 reposts in July 2023 using an application programming interface tool. Two independent researchers categorized the contents of the posts into 7 main categories and then summarized recommended weight loss strategies.

Results: We analyzed 815 English and 1213 Japanese posts. The most popular main category of the content was "how to change weight" in both languages. The Japanese posts were more likely to mention "how to change weight" (n=571, 47.1%) and "recipes to change weight" (n=114, 9.4%) than the English posts (n=195, 23.9% and n=10, 1.2%, respectively), whereas the English posts were more likely to mention "will or experience to change weight" (n=167, 20.5%), "attitudes toward weight status" (n=78, 9.6%), and "public health situation" (n=44, 5.4%) than Japanese posts. Among 146 English and 541 Japanese posts about weight loss strategies, the predominant strategies were diet (n=76, 52.1% in English and n=170, 31.4% in Japanese) and physical activities (n=56, 38.4% and n=295, 54.5%, respectively). The proportion of posts mentioning both diet and physical activity was smaller in Japanese (n=62, 11.5%) than in English (n=31, 21.2%). Among 76 English and 170 Japanese posts about dietary behaviors for weight loss, more than 60% of posts recommended increasing intakes of specific nutrients or food groups in both languages. The most popular dietary component recommended to increase was vegetables in both English (n=31, 40.8%) and Japanese (n=48, 28.2%), followed by protein and fruits in English and grains or potatoes and legumes in Japanese. Japanese posts were less likely to mention reducing energy intake; meal timing or eating frequency; or reducing intakes of specific nutrients or food groups than the English posts. The most popular dietary component recommended to decrease was alcohol in English and confectioneries in Japanese.

Conclusions: This study characterized user interest in weight management and suggested the potential of X as an information source for weight management. Although weight loss strategies related to diet and physical activity were popular in both English and Japanese, some differences in the details of the strategies were present, indicating that X users are exposed to different information in English and Japanese.