Serum thyroid hormone concentrations and weight loss relationships in eight obese women during semistarvation

Abstract

Eight obese female patients were studied over a period of 15 days whilst on 300 kcal diet. Serum levels of thyroxine and free throxine index were not altered significantly by semistarvation. A TRH test performed before and after the diet showed no appreciable change. Weight loss was intially rapid but later slowed despite good patients compliance. Serum concentrations of T 3 and reverse T 3 (rT3) early decreased (p less than 0.01) and increased (p less than 0.05) respectively, but returned towards control levels even before discontinuation of semistarvation. There was a positive correlation between the percentage decrease in body weight and the percentage increase in serum rT 3 (p less than 0.001), and a negative correlation between decrease in body weight and decrease in serum T 3 (p less than 0.001). Our results do not suggest that the variations in serum triiodothyronines limit the weight loss; it is probable, on the contrary, that the weight loss promotes the observed variations in thyroid hormones by as yet unknown adaptive metabolic forces.

Relationship Between the Changes in Serum Thyroid Hormone Levels and Protein Status During Prolonged Protein Supplemented Caloric Deprivation

“…Thus, our subjects developed a progressive decline in the serum T3 levels despite the protein supplementation. The magnitude of the decrease in the serum T3 concentrations correlated directly with the weight loss, as previously reported (Visser et al, 1978;Adami et al, 1979;Moore et al, 1980) and negatively with the return of the nitrogen balance towards zero ( Table 3). The heaviest individuals had the greatest weight loss and the largest percent decrease in serum T3 levels during the study.…”

“…The only other comparable study (O'Brian et al, 1980) showed that caloric deprivation induced by 200, 400 or 600 kcal per day as protein resulted in an insignificant transient rise in the total T4 levels. Others have reported that total T4 values increased (Rabast et a[., 1981; Osburne er ul., 1983), decreased (Carlson et al, 1977) or remain unchanged (Portnay et al, 1974;Vagenakis et al, 1975;Spaulding et al, 1976;Grant et ul., 1978;Visser et al, 1978;Adami et al, 1979;Scriba et al, 1979;Jung et al, 1980;Moore et al, 1980;Moreira-Andres et a/., 1980;Serog et a/., 1982), while the free T4 index and free T4 levels estimated by equilibrium dialysis were increased (Portnay et a/., 1974;Scriba et a/., 1979;Moreira-Andres et al, 1980;Rabast et a/., 1981) or remained unaltered (Carlson et a/., 1977;Adami et al, 1979) during total fasting or with reduced caloric intake. These differences may be the result of different dietary regimens and reflect a spectrum of alterations related to the severity of the catabolic state, as has been observed in patients with nonthyroidal illnesses (Kaptein, 1985).…”

Starvation induced hypothyroidism involves perturbations in thyroid superoxide‐sod system in pigeons

“…In fact, reports are available, indicating fasting-induced suppression of TSH, causing release of T 4 and T 3 from the thyroid gland [6][7][8]. There are reports indicating that with short-term fasting or dieting, T4 concentrations change very little [45,46]. With prolonged fasting, however, T4…”

Resting and exercise energy use in Antarctica: effect of 50% restriction in temperate climate energy requirements

“…Measurements of reverse T3 (rT3) and its kinetic parameters may be helpful in future studies of energy deprivation in this environment to help understand the role of the different deiodinase (D) activities of D1, D2 and D3 in the generation of the Polar T3 Syndrome. Normally, rT3 increases with energy restriction as a function of decreased activity of D1 and tissue‐specific increased D3 activity 44–48 . We would speculate that rT3 might not increase in this setting because of increased deiodinase activity of either D1 or D2, which could contribute to the observed increased T3 plasma appearance and clearance rate 5 …”

“…Normally, rT3 increases with energy restriction as a function of decreased activity of D1 and tissue-specific increased D3 activity. [44][45][46][47][48] We would speculate that rT3 might not increase in this setting because of increased deiodinase activity of either D1 or D2, which could contribute to the observed increased T3 plasma appearance and clearance rate. 5 The fall in Tty seen as possibly part of the human hypothermic cold adaptation process was present when compared with the RG (predeployment) measured in a temperate climate.…”