Pregnancy creates significant alterations in energy metabolism which itself is a physiological adaptation to provide continuous flow of energy metabolites to the foetus. The state of insulin resistance created by hormonal changes in pregnancy enables free flow of glucose to the foetus and allows its absorption through facilitated diffusion. As glucose is preferentially available for the foetus, maternal fasting glucose level would be less than that of a non-pregnant state and in contrast plasma ketones and free fatty acids levels are elevated, resulting in a state of accelerated starvation. These metabolic alterations place a pregnant woman at a higher risk of developing euglycaemic ketoacidosis when allowed to fast for prolonged periods due to medical, surgical and psychological reasons. We report a rare case of euglycaemic ketoacidosis causing severe increased anion gap metabolic acidosis in a non-diabetic mother following surgery for appendicitis at a gestation of 27 weeks.