Effect of long-term calorie restriction with adequate protein and micronutrients on thyroid hormones.
J Clin Endocrinol Metab. 2006 Aug;91(8):3232-5. Epub 2006 May 23. PMID: 16720655
Washington University School of Medicine, 4566 Scott Avenue, Campus Box 8113, St. Louis, MO 63110, USA. email@example.com
CONTEXT: Caloric restriction (CR) retards aging in mammals. It has been hypothesized that a reduction in T(3) hormone may increase life span by conserving energy and reducing free-radical production. OBJECTIVE: The objective of the study was to assess the relationship between long-term CR with adequate protein and micronutrient intake on thyroid function in healthy lean weight-stable adult men and women. DESIGN, SETTING, AND PARTICIPANTS: In this study, serum thyroid hormones were evaluated in 28 men and women (mean age, 52 +/- 12 yr) consuming a CR diet for 3-15 yr (6 +/- 3 yr), 28 age- and sex-matched sedentary (WD), and 28 body fat-matched exercising (EX) subjects who were eating Western diets. MAIN OUTCOME MEASURES: Serum total and free T(4), total and free T(3), reverse T(3), and TSH concentrations were the main outcome measures. RESULTS: Energy intake was lower in the CR group (1779 +/- 355 kcal/d) than the WD (2433 +/- 502 kcal/d) and EX (2811 +/- 711 kcal/d) groups (P<0.001). Serum T(3) concentration was lower in the CR group than the WD and EX groups (73.6 +/- 22 vs. 91.0 +/- 13 vs. 94.3 +/- 17 ng/dl, respectively) (P