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Effect of Weight Loss after Bariatric Surgery on Thyroid-Stimulating Hormone Levels in Euthyroid Patients with Morbid Obesity.
Juiz-Valiña, P, Outeiriño-Blanco, E, Pértega, S, Varela-Rodriguez, BM, García-Brao, MJ, Mena, E, Pena-Bello, L, Cordido, M, Sangiao-Alvarellos, S, Cordido, F
Nutrients. 2019;11(5)
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Obesity is associated with many health issues, including thyroid problems. The aim of this observational study was to investigate the effect of weight loss surgery on thyroid hormones. 129 morbidly obese people with normal thyroid function were included in the study. 12 months after weight loss surgery, the levels of thyroid stimulating hormone (TSH) had significantly decreased from 3.3 to 2.1 µU/mL. Levels of the thyroid hormone free thyroxine (T4) also significantly decreased from 1.47 to 1.12 ng/dL. Those that lost more weight following surgery tended to have a greater reduction in TSH. Fasting blood glucose also significantly improved after surgery. The authors concluded that obesity is associated with raised TSH levels, and this makes diagnosing thyroid problems in people with morbid obesity more complicated.
Abstract
Obesity is associated with several endocrine abnormalities, including thyroid dysfunction. The objective of this study was to investigate the effect of weight loss after bariatric surgery on thyroid-stimulating hormone (TSH) levels in euthyroid patients with morbid obesity. We performed an observational study, evaluating patients with morbid obesity submitted to bariatric surgery. We included 129 patients (92 women) and 31 controls (21 women). Clinical, anthropometric, biochemical, and hormonal parameters were evaluated. The primary endpoint was circulating TSH (µU/mL). Fasting TSH levels were higher in the obese group (3.3 ± 0.2) than in the control group (2.1 ± 0.2). The mean excessive body mass index (BMI) loss (EBMIL) 12 months after bariatric surgery was 72.7 ± 2.1%. TSH levels significantly decreased in the obese patients after surgery; 3.3 ± 0.2 vs. 2.1 ± 0.2 before and 12 months after surgery, respectively. Free thyroxine (T4) (ng/dL) levels significantly decreased in the obese patients after surgery; 1.47 ± 0.02 vs. 1.12 ± 0.02 before and 12 months after surgery, respectively. TSH decreased significantly over time, and the decrement was associated with the EBMIL. In euthyroid patients with morbid obesity, weight loss induced by bariatric surgery promotes a significant decline of the increased TSH levels. This decrement of TSH is progressive over time after surgery and significantly associated with excess BMI loss.
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Thyroid hormones and changes in body weight and metabolic parameters in response to weight loss diets: the POUNDS LOST trial.
Liu, G, Liang, L, Bray, GA, Qi, L, Hu, FB, Rood, J, Sacks, FM, Sun, Q
International journal of obesity (2005). 2017;41(6):878-886
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The role of thyroid hormones in diet-induced weight loss and subsequent weight regain is largely unknown. The aim of this study was to examine the associations between thyroid hormones and changes in body weight and resting metabolic rate (RMR) in adults on a calorie-restricted diet. Data analysis was conducted among 569 overweight and obese adults with normal thyroid function participating in the 2-year Prevention of Obesity Using Novel Dietary Strategies (POUNDS) LOST clinical trial. Participants were assigned to diets that represented a reduced caloric intake of 750 kcal/day from estimated energy needs. Changes in body weight and RMR were assessed during the 2-year intervention. Thyroid hormones (free triiodothyronine (T3), free thyroxine (T4), total T3, total T4 and thyroid-stimulating hormone (TSH)), anthropometric measurements and biochemical parameters were assessed at baseline, 6 months and 24 months. Participants lost an average of 6.6 kg of body weight during the first 6 months and subsequently regained an average of 2.7 kg of body weight over the remaining period from 6 to 24 months. Baseline free T3, total T3 and free T4 were associated with baseline body weight, body mass index and RMR. Total T4 and TSH were not associated with these parameters. Higher baseline free T3 and free T4 levels were significantly associated with a greater weight loss during the first 6 months. Thyroid hormones did not predict weight regain in 6-24 months. In addition, changes in free T3 and total T3 levels were positively associated with changes in body weight, RMR, body fat mass, blood pressure, glucose, insulin, triglycerides and leptin at 6 months and 24 months. The authors concluded that on a reduced-calorie diet, higher baseline free T3 and free T4 predicted more weight loss, but not weight regain among overweight and obese adults with normal thyroid function. These findings reveal a role of thyroid hormones in body weight regulation and may help identify individuals more responsive to weight loss diets.
Abstract
BACKGROUND The role of thyroid hormones in diet-induced weight loss and subsequent weight regain is largely unknown. OBJECTIVES To examine the associations between thyroid hormones and changes in body weight and resting metabolic rate (RMR) in a diet-induced weight loss setting. SUBJECTS/METHODS Data analysis was conducted among 569 overweight and obese participants aged 30-70 years with normal thyroid function participating in the 2-year Prevention of Obesity Using Novel Dietary Strategies (POUNDS) LOST randomized clinical trial. Changes in body weight and RMR were assessed during the 2-year intervention. Thyroid hormones (free triiodothyronine (T3), free thyroxine (T4), total T3, total T4 and thyroid-stimulating hormone (TSH)), anthropometric measurements and biochemical parameters were assessed at baseline, 6 months and 24 months. RESULTS Participants lost an average of 6.6 kg of body weight during the first 6 months and subsequently regained an average of 2.7 kg of body weight over the remaining period from 6 to 24 months. Baseline free T3 and total T3 were positively associated, whereas free T4 was inversely associated, with baseline body weight, body mass index and RMR. Total T4 and TSH were not associated with these parameters. Higher baseline free T3 and free T4 levels were significantly associated with a greater weight loss during the first 6 months (P<0.05) after multivariate adjustments including dietary intervention groups and baseline body weight. Comparing extreme tertiles, the multivariate-adjusted weight loss±s.e. was -3.87±0.9 vs -5.39±0.9 kg for free T3 (Ptrend=0.02) and -4.09±0.9 vs -5.88±0.9 kg for free T4 (Ptrend=0.004). The thyroid hormones did not predict weight regain in 6-24 months. A similar pattern of associations was also observed between baseline thyroid hormones and changes in RMR. In addition, changes in free T3 and total T3 levels were positively associated with changes in body weight, RMR, body fat mass, blood pressure, glucose, insulin, triglycerides and leptin at 6 months and 24 months (all P<0.05). CONCLUSIONS In this diet-induced weight loss setting, higher baseline free T3 and free T4 predicted more weight loss, but not weight regain among overweight and obese adults with normal thyroid function. These findings reveal a novel role of thyroid hormones in body weight regulation and may help identify individuals more responsive to weight loss diets.