It is unclear in medicine if a malfunctioning thyroid leads to weight gain or if an obese patient develops high thyroid stimulating hormone levels (TSH) because excessive fat interferes with the hypothalamic-pituitary pathway that releases thyroid hormone. But the one thing that is clear is that there will be more patients diagnosed with underactive thyroid as the population becomes more and more obese. 
What Type of Work-out is Right for Hypothyroidism
The kind of exercise is essential when patients begin to manage their under-performing thyroids. One study was conducted to determine what kind of training was the most efficient at altering the levels of thyroid hormones in the body. The hormones analyzed of relevance were TSH, triiodothyronine (luckily referred to as T3 almost exclusively) and thyroxine (T4). When a patient is diagnosed with hypothyroidism, TSH levels will be elevated because the body is trying to "call" for more thyroid hormones to be released into the body while T3 and T4 are responsible for altering the metabolism and are often both reduced in patients with hypothyroidism.  Researchers asked participants to partake in a specific exercise routine that was carried out at low intensity, medium intensity and high intensity and the effects on the thyroid hormones were noted before and after the exercises concluded. The study found that if participants exceeded medium intensity, their TSH and T4 levels continued to rise while their T3 levels began to fall. Although this may suggest that your thyroid function may actually get worse as you exercise intensely, your thyroid hormones are used up faster to generate energy due to the metabolic demand.
Exercises to Consider to Combat Hypothyroidism
Studies confirm that hypoxic conditions are beneficial to increase thyroid function and as stated above, this is best achieved with an extended aerobic type of workout . Thankfully, the list of options are extensive for patients and they can pick activities that are most attractive subjectively as they manage their underactive thyroid.
Not only is this exercise appropriate for all ages due to the low level of stress placed on joints but it is also is one of the most effective aerobic exercises .The important thing to remember is that just going to the pool a few times a month will not make a difference. In one study testing the effectiveness of swimming on an obese population, 9 participants were enrolled in a swimming program where they were forced to swim with a low-intensity effort, three times a week in 45-minute sessions with the study lasting ten weeks. At the end of the study, compared to the control group that had no particular exercise routine, there was no difference at all between the two populations when it came to parameters like cholesterol levels, body mass, serum glucose and thyroid levels.  As can be seen from the study, participants must strive to make their exercises meaningful with exertion.
Walking is something that can be done regularly and has a little impact on joints as well to make routines more likely. In one study, participants were asked to walk through hilly terrain for a total of 12 kilometers, and their metabolic demand was analyzed during the routine. At the conclusion of the study, there was significantly more energy metabolized from fatty tissue compared to walks from a flat level. 
The focus of this article is to cover topics that are possible for the majority of the population considering that patients with hypothyroidism have reduced output thresholds, increased heart rates and increased respiratory efforts compared to healthy individuals so more demanding aerobic exercises like hiking and running may be too strenuous for the average hypothyroid patient.