Rashi on Deuteronomy 28:53/רש"י על דברים כ״ח:נ״ג

1ואכלת … בשר בניך … במצור AND THOU SHALT EAT … THE FLESH OF THY SONS … IN THE SIEGE, [AND IN THE DISTRESS] — Because they (the enemies) will besiege the city and there will consequently be distress— i.e. the stress of famine.