Thyroid hormone therapy and weight loss
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Thyroid Hormone Therapy and Weight Loss: Clinical Evidence and Mechanisms
Effects of Thyroid Hormone Therapy on Weight Loss in Obesity
Research shows that thyroid hormones, especially triiodothyronine (T3) and thyroxine (T4), play a key role in regulating metabolism and energy expenditure. However, the use of thyroid hormone therapy for weight loss in people without thyroid disease remains controversial and largely unsupported by strong evidence. Systematic reviews and clinical studies have found that while T3 therapy can lower thyroid-stimulating hormone (TSH) and T4 levels during caloric restriction in obese individuals, there is no consistent evidence that T3 or T4 therapy leads to significant weight loss, increased metabolic rate, or changes in heart rate in these populations 125.
Weight Loss in Hypothyroid vs. Euthyroid Individuals
For people with hypothyroidism, treating with levothyroxine (T4) can result in modest weight loss, but this is mostly due to loss of water weight rather than fat. In contrast, in euthyroid (normal thyroid function) individuals, there is no consistent evidence that thyroid hormone therapy induces weight loss . Large population studies have shown that TSH and T3 levels are often higher in obese individuals, but this does not mean that giving thyroid hormones will help with weight loss in those with normal thyroid function 29.
Thyroid Hormones and Weight Loss Diets
In weight loss interventions among overweight and obese adults with normal thyroid function, higher baseline levels of free T3 and free T4 are associated with greater weight loss during the initial phase of dieting. However, thyroid hormone levels do not predict weight regain after the initial weight loss period. Changes in T3 levels are also linked to changes in body weight, resting metabolic rate, and body fat mass during weight loss . Similar findings have been observed in children and adolescents, where changes in T3 and TSH levels often correlate with changes in body composition during weight loss interventions, but T4 levels usually remain unchanged and are not associated with weight loss 78.
Risks and Limitations of Thyroid Hormone Therapy for Weight Loss
The use of thyroid hormone therapy in people without thyroid disease can induce a state of subclinical hyperthyroidism, which carries risks such as heart problems and bone loss 12510. Studies have also shown increased mortality in certain patient groups treated with thyroid hormones, and the overall quality of evidence supporting thyroid hormone therapy for weight loss is low due to small study sizes and inconsistent results .
Novel Approaches: Targeted Thyroid Hormone Delivery
Recent experimental approaches, such as delivering T3 using glucagon-modified liposomes targeted to the liver and fat tissue, have shown promise in animal models. This method reduced body weight and improved metabolic parameters in obese mice without causing the harmful side effects typically seen with systemic thyroid hormone therapy . Additionally, thyroid hormone analogues that separate beneficial metabolic effects from harmful side effects are being developed and may offer future therapeutic options for obesity .
Conclusion
Thyroid hormones are important regulators of metabolism and body weight, but current evidence does not support the routine use of thyroid hormone therapy for weight loss in people with normal thyroid function. While some individuals with hypothyroidism may experience modest weight loss with treatment, the risks of thyroid hormone therapy in euthyroid individuals outweigh the potential benefits. New targeted therapies and analogues may offer safer options in the future, but more research is needed to confirm their effectiveness and safety 1245+2 MORE.
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Most relevant research papers on this topic
Thyroid hormone therapy for obesity and nonthyroidal illnesses: a systematic review.
Thyroid hormone therapy's effectiveness in treating obesity and nonthyroidal illnesses remains inconclusive, while causing subclinical hyperthyroidism.
Glucagon-modified Liposomes Delivering Thyroid Hormone for Anti-obesity Therapy.
Glucagon-modified liposomes effectively deliver thyroid hormone to the liver and adipose tissues, minimizing side effects and providing an effective anti-obesity therapy strategy.
Triiodothyronine and leptin repletion in humans similarly reverse weight-loss-induced changes in skeletal muscle.
Thyroid hormone repletion can reverse weight-loss-induced changes in skeletal muscle, suggesting potential as an adjunctive therapy to help sustain weight loss.
Thyroid hormone axis and anthropometric recovery of children/adolescents with overweight/obesity: a scoping review
Thyroid hormone levels positively correlate with body composition changes in children and adolescents with overweight/obesity, but have no significant association with weight loss.
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