With long-term administration (> 7 weeks), two factors lead to sudden cessation of weight loss (after weeks of steady, rapid weight loss):
1. Factor 1: rapidly acquired tolerance to the drug. EX:
- One patient, on a daily dose of 320 mg, resulting in a RMR ↑26%, lost weight at an average rate of 1.4 kg (3 lb) weekly x 7 weeks. Then, for 6 weeks, she lost no weight even though the dose was raised to 400 mg daily. A RMR determination at this time showed that RMR ↑ by a mere 6% (relatively rare)
- The acquired tolerance is rapidly lost if the drug is discontinued for as short a period as two weeks. The dinitrophenol may then be resumed at a lower dosage level with its original effect on the patient.
2. Factor 2: Edema (profound); DNP promotes water storage in the tissues of the body. EX:
- Another patient, on a daily dose of 300 mg, resulting in a RMR ↑46%, lost an average of 0.9 kg (2 lb) weekly x 8 weeks. Then, she suddenly stopped losing weight. The dosage was increased to 400 mg daily x 4 weeks with no resultant weight loss. A RMR determination at this time showed that RMR ↑ by a considerable 62% (common)
- Naturally, cessation from DNP at such a time results in dramatic water, and therefore weight, loss.
[12] Simkins, S. (1937). Dinitrophenol and dessicated thyroid in the treatment of obesity. Journal of the American Medical Association, 108(25), 2110. doi:10.1001/jama.1937.02780250024006