Exploring the Link Between Thyroid Disorders and Obesity: Mechanisms, Impacts, and Clinical Implications

Obesity and thyroid dysfunction are among the most significant challenges in endocrinology, frequently overlapping to create complexities in weight management. Even after achieving euthyroidism, weight variations persist, significantly affecting patients' quality of life. This review explores the mechanisms linking hypothyroidism and hyperthyroidism to weight fluctuations, emphasizing their impact on basal metabolic rate, appetite regulation, glucose and lipid metabolism, and thermogenesis.

We conducted a comprehensive review using PubMed and Google Scholar, applying the search criteria: (obesity OR overweight) AND (Hashimoto's thyroiditis OR hyperthyroidism OR hypothyroidism OR Thyroid Cancer). From this search, we reviewed 500 publications and finally included 71 publications, focusing on broad clinical questions regarding the role of thyroid hormones in weight regulation and metabolism, the impact of thyroid disorders and their treatments on obesity, and approaches for managing obesity in the context of thyroid dysfunction.

In hypothyroidism, the impact of levothyroxine therapy on weight changes is discussed, along with the potential role of T3 supplementation. For hyperthyroid patients, the effects of antithyroid medications, radioactive iodine therapy, and thyroidectomy on weight regulation are explored. Pharmacological and nonpharmacological strategies for managing obesity in thyroid disorders are reviewed. Lifestyle interventions and pharmacotherapies are evaluated for their efficacy and potential effects on thyroid function. Lastly, the implications of bariatric surgery are explored, including its effects on thyroid function, medication absorption, and postsurgical management of thyroid disorders.

This review underscores the importance of an integrated, multidisciplinary approach to managing obesity in the context of thyroid dysfunction to optimize patient outcomes.