Metabolic Insufficiency as a Limiting Factor in the Dietetic Treatment of Obesity

Summary

Previous observations that acute total fasting decreases serum T₃ and increase rT₃ has prompted the following study. 17 obese women were placed on a 1000 kcal/day weight-reducing diet, and body weight (BW), serum T₄, RT₃U, T₃, rT₃, TSH and the Achilles tendon reflex (ATR) were estimated before and after each month for 3 consecutive months of the diet. The results showed a consistent decrease in serum T₃, an inconsistent increase in rT₃, a consistent prolongation of the ATR and a levelling-off of the BW loss after the second month of the diet. At 3 months there was a negative correlation between the decrease in BW and the increase in ATR, i.e. the more abnormal the ATR became, the less weight the patient lost. It is concluded: 1) Even a moderate hypocaloric diet in ambulatory patients induces a disturbance in the peripheral conversion of T₄ to T₃ and a secondary state of metabolic insufficiency. 2) This insufficiency is probably related to the observed tendency of the BW loss to level off after two months. 3) A controlled trial of physiologic doses of T₃, such as 40 μg/day, seems indicated, as opposed to pharmacologic doses of T₃ used by previous investigators.

Key-Words:

Achilles Tendon Reflex - Free Thyroxine Index - Hypocaloric Diet - Hypometabolism - Obesity - Photomotograph - Reverse Triiodothyronine - Skinfold Thickness - Thyrotropin - Thyroxine - Triiodothyronine