Age

18–any

Sex

ALL

Healthy volunteers

Not accepted

Age ≥18 years
Histologically confirmed metastatic breast cancer
Menopausal or medically ovarian suppressed
Currently receiving capivasertib therapy (2 tablets twice daily, 4 days per week)
Stable on current capivasertib regimen for at least 2 weeks
an ECOG performance status of 0-1
BMI ≥25kg/m2
Able to provide informed consent
Willing to comply with study procedures including CGM wear, food tracking by mCC app and dietary modifications
Access to smartphone or tablet for mobile application use

Type 1 diabetes mellitus
Uncontrolled type 2 diabetes (HbA1c \>9.0%)
History of severe hypoglycemia
Eating disorders or contraindications to fasting
Pregnancy or breastfeeding
Significant gastrointestinal disorders affecting food absorption
Unable to fast for medical reasons
Concurrent participation in other dietary intervention studies
A history of significantly abnormal lab results within 4 weeks of consent date, such as hematologic (Hgb \< 10.0, platelets \< 100), hepatic (LFTs \> 2X nl), renal (Cr \> 1.5)

Fast-Her: Fasting Effects on Breast Cancer Treatment