Weight Loss in Hyperthyroidism
Jun
4
Written by:
6/4/2011
Thyroid hormones stimulate metabolism, including energy expenditure and the metabolism of lipids, carbohydrates, proteins, and minerals. The effects of this stimulation include: weight loss, increased food intake, and an increase in heat production. The extent of these changes varies substantially among different patients.
In one large study of hyperthyroidism, 52% of patients in their 20's lost weight; 67% of people in their forties lost weight; and 82% of people in their seventies lost weight. Weight loss occurred despite an increase in appetitel in older patients, appetite increases less and sometimes decreases, explaining their higher frequency of weight loss.
In animal studies, administration of thyroid hormone causes an increased metabolic rate in all tissues except the spleen, testes, and brain. Increased metabolism of cell mitochondria and the increased metabolism of lipids, protein and carbohydrates leads to nutrient deficiencies, increased glucose absorption, increased gastric emptying and a loss of lean body mass due to loss of muscle protein (to a greater extent than loss of body fat).
Source: Metabolic Changes in Thyrotoxicosis, Werner & Ingbar's The Thyroid, 8th Edition.