Fasting in obesity. Thiamine depletion as measured by erythrocyte transketolase changes

Abstract

In 3 subjects studied without previous thiamine therapy, transketolase activity fell and thiamine pyrophosphate increased by the 4th day of the fast. When 50 mg thiamine was given, these values returned to normal within 2 hr. In 2 of 3 subjects who fasted after receiving 50 mg of thiamine normal values were maintained for only 10 days with subsequent marginal biochemical thiamine deficiency then recurring. In 2 patients given a single dose of 2 mg of thiamine after abnormal transketolase values were obtained, there was a prompt restoration of normal activity. A marginal biochemical defect, however, was again apparent in 48 hr. Daily doses of as little as 0.5 mg thiamine were sufficient to maintain normal transketolase activity. Thiamine depletion thus occurred rapidly in the fasting obese patient.