Abstract Background: Diet is a modifiable risk factor for breast cancer risk and mortality. Current guidelines recommend a diet that provides a diverse array of nutrients, comprised predominantly of fruits/vegetables and whole grains, with limited added sugar. The Healthy Living Program (HLP) is a clinical program at Memorial Sloan Kettering Cancer Center for patients with early-stage breast cancer that offers longitudinal, personalized lifestyle management starting at the time of diagnosis. Here, we report dietary patterns among the HLP cohort and association with baseline body mass index (BMI). Methods: We included all patients enrolled in the HLP from September 2020-February 2022. At the time of enrollment, participants complete a survey containing the National Cancer Institute (NCI) Dietary Screener Questionnaire (DSQ), which consists of consumption frequency questions for 26 food items over the past month. Total daily intake equivalents are calculated for foods from every diet factor group according to standard NCI DSQ scoring as follows: 1) Total daily cup equivalents of fruits/vegetables, which includes fruit, fruit juice, salad, potatoes, beans, other vegetables, tomato sauce, salsa, and pizza; 2) Total daily ounce equivalents of whole grains, which includes cereal, whole grain bread, whole grain rice, and popcorn; 3) Total teaspoon (tsp) equivalents of added sugars from candy, doughnuts, cookies/cake/pie, cereal, ice cream, and sugar-sweetened beverages including soda, fruit drinks, and sugar/honey in coffee/tea. Adherence to recommended daily intake of fruits/vegetables, whole grains, and added sugars was assessed as per the 2020-2025 Dietary Guidelines, the American Institute for Cancer Research, and the World Health Organization guidelines. Patient and tumor characteristics were abstracted from medical records. Results: Among the 399 patients included, the median age at diagnosis was 58 and median baseline BMI was 26.1 kg/m2. 45 patients had carcinoma in situ (11.3%), 296 had stage I disease (74.2%), 51 had stage II disease (12.8%), and 7 had stage III disease (1.8%). 316 had hormone-receptor positive disease (89.3%), 24 had HER2-positive disease (6.8%), and 26 had triple-negative disease (7.3%). 106 participants (27%) met the guideline recommendation of ≥4-5 cup equivalents of fruits/vegetables daily and 3 participants (0.8%) met the guideline recommendation of ≥3 ounces equivalents of whole grains daily. All patients in the cohort met the guideline recommendation of < 6 tsp equivalents of added sugars daily. Only 2 patients (0.5%) met guidelines for all three diet factors. Baseline BMI was significantly higher among patients who did not meet the recommended fruit/vegetable intake than among those who did (26.9 kg/m2 vs. 24.5 kg/m2, p=0.016). There were no significant differences in BMI between those who did and did not adhere to the other diet factor guidelines and no significant association between tumor stage or histology and dietary guideline adherence. Conclusion: Most patients with early-stage breast cancer did not meet the recommended daily intake of fruits/vegetables or whole grains. Participants who did not meet the fruit and vegetable intake guideline had significantly higher BMI at diagnosis. These findings indicate that lifestyle assessment near the time of breast cancer diagnosis identifies patients that could benefit from personalized dietary interventions to optimize prognostic factors such as BMI. Citation Format: Bethina Liu, Sherry Shen, Erica Salehi, Yuan Chen, Nicolas Toumbacaris, Johnny Allsop, Cara Anselmo, Stacie Corcoran, Bridget Kelly, Rocco Magnoli, Andrea Smith, Melissa Emerzian, Julia Brockway-Marchello, Doreen Bacotti, Mark E. Robson, Neil M. Iyengar. Dietary patterns among women with early-stage breast cancer from the Healthy Living Program [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-08-07.