Thyroid hormones and changes in body weight and metabolic parameters in response to weight loss diets: the POUNDS LOST trial

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 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 6–24 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 ± standard error was −3.87±0.9 vs −5.39±0.9 kg for free T3 (P trend=0.02) and −4.09±0.9 vs −5.88±0.9 kg for free T4 (P trend=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.

Central Resistance to Thyroid Hormones in Morbidly Obese Subjects Is Reversed after Bariatric Surgery-Induced Weight Loss

“…Increased FT4 in obesity has been found in some studies [14]. Several studies have reported different results regarding the variation of TSH after BS and the relation of TSH decrease with weight loss [15][16][17][18]. Most [15,17], but not all [18] studies have found a decrease in circulating TSH after the operation.…”

“…The alteration of thyroid function and the effect of BS on thyroid function is not fully understood. There are previous studies showing different results regarding the variation of thyroid stimulating hormone (TSH) after weight loss surgery [15][16][17][18][19]. The free thyroxine (FT4) values in obesity and the variation after surgery are even more conflicting [15].…”

Hormony tarczycy i otyłość: znana, lecz słabo rozpoznana relacja

“…These connections establish a new hypothalamic-pituitary-adipose tissue axis [55,56]. Under this scenario, TH deficiency (hypothyroidism) with the consequent increase in TSH could promote weight gain [57,58].…”

“…In animal models it has been observed that TSH stimulates the secretion of leptin through a direct effect on the adipocytes, probably through the TSH receptors expressed in this tissue [38,57,64]. Figure 3 shows a hypothetical model based in the previously discussed information.…”

Impact of the Co-Administration of N-3 Fatty Acids and Olive Oil Components in Preclinical Nonalcoholic Fatty Liver Disease Models: A Mechanistic View

“…For example, (i) preservation of liver tissue regeneration post-hepatectomy can be obtained by a L-3,3 ,5-triiodothyronine (T 3 ) plus methylprednisolone treatment [8]; (ii) high-fat diet (HFD)-induced liver steatosis can be diminished by n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) and extra virgin olive oil (EVOO) [9]; (iii) combined T 3 and fish oil supplementation suppresses ischemia-reperfusion inflammatory liver injury [10]; whereas (iv) resveratrol and enalapril improved glucose and lipid profiles by decreasing lipogenic gene expression [11]. Interestingly, an inverse correlation between serum free thyroxine (T 4 ) levels and hepatic steatosis was established in overweight and obese patients [12] or with elevated serum thyroid-stimulating hormone concentrations in overweight/obese children [13], while higher baseline levels of T 3 and T 4 predict more weight loss, but not weigh regain, in overweight/obese patients with normal thyroid function subjected to weight loss diets [14]. Collectively, these evidences point to the concept that natural products, drugs, and thyroid hormones constitute hormetic agents or hormetins, which favor beneficial effects by acting at low dosages through one or more pathways of maintenance and repair, thus conferring resistance to subsequent, otherwise harmful, conditions of increased stress [15], including metabolic stress [16].…”