Obesity-focused dietary interventions in breast cancer care: A comprehensive review of medical nutrition therapy approaches and efficacy in prevention and treatment

Obesity is associated with an increased risk of developing breast cancer, particularly in postmenopausal women, through mechanisms such as excessive estrogen production, insulin resistance, and chronic low-grade inflammation, all of which promote tumor initiation and progression. Alterations in the gut microbiota, frequently observed in obesity, further exacerbate this risk by influencing estrogen metabolism, modulating immune responses, and promoting systemic inflammation, thereby creating a microenvironment conducive to breast cancer growth. Medical nutrition therapy plays a crucial role in managing these interrelated conditions, with dietary interventions such as the Mediterranean diet, ketogenic diet, and intermittent fasting showing potential to reduce weight, improve metabolic health, modulate the gut microbiome, and positively influence inflammatory and hormonal signaling. While short-term outcomes are promising, long-term studies are required to confirm their effects on breast cancer survival and recurrence. Personalized nutrition—accounting for genetic, epigenetic, and microbiome profiles—is emerging as a highly effective approach to enhance therapeutic outcomes. Integrating targeted nutritional strategies into breast cancer treatment protocols is essential to improve prognosis, optimize therapy responses, and enhance patients’ quality of life. This narrative review examines the role of nutritional therapies in the prevention and management of obesity and breast cancer, emphasizing their impact on tumor biology, treatment efficacy, and patient health. © 2026 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license. http://creativecommons.org/licenses/by-nc-nd/4.0/