[Thyroid hormones during a hypocaloric diet in obese patients]

Area of Science:

• Endocrinology
• Nutritional Science
• Metabolic Research

Context:

• Thyroid hormones play a crucial role in regulating metabolism.
• Dietary carbohydrate restriction is a common weight-loss strategy.
• Understanding the impact of diet on thyroid function is essential for metabolic health.

Purpose:

• To investigate the effects of a very low-carbohydrate diet (800-1000 kcal, 60-80g carbohydrates) on thyroid hormone levels.
• To analyze changes in triiodothyronine (T3), reverse triiodothyronine (RT3), thyroxine (T4), and thyroid-stimulating hormone (TSH) over 15 days.
• To correlate observed hormonal shifts with body weight changes.

Summary:

• Forty-five subjects were monitored for thyroid hormone levels (T3, RT3, T4, TSH) and weight during a 15-day low-carbohydrate diet.
• No significant changes were observed in T4, FT4 index, or TSH levels between genders or over time.
• A significant decrease in T3 and a significant increase in RT3 were observed from day 1 to day 15, particularly from day 4 to 15, leading to a decreased T3/RT3 ratio, which correlated with weight loss.

Impact:

• Demonstrates that significant alterations in thyroid hormone profiles, specifically T3 and RT3, occur during short-term carbohydrate restriction.
• Highlights the T3/RT3 ratio as a sensitive indicator of metabolic adaptation to low-carbohydrate diets.
• Provides insights into the physiological responses to dietary interventions, relevant for weight management and metabolic health research.