This suggests that hormones are actually playing a huge role in weight gain, regardless of the diet of the person. An underactive thyroid, or hypothyroidism, only affects women. It develops in around three percent of females aged 20 to 40. It creeps along over the years with gradual weight gain that appears natural but is actually due to this issue.
The condition occurs when the thyroid gland in the neck does not produce enough thyroxine, a hormone that regulates the amount of energy the body produces, among other functions. Other symptoms can include dry skin and hair. Conversely, an overactive thyroid produces too much thyroxine, causing metabolism to speed up. The sufferer often loses weight even while experiencing a greater appetite.
Also, it has been suggested that any fluctuations in weight may not necessarily be because of dieting or breakdowns in personal discipline. People suffering from infections of the thyroid, known as viral thyroiditis, may move through overactive and underactive phases before they finally return to normal.
In men, an unfortunate cycle can begin as body fat converts testosterone to estrogen, shuttering also production of chemicals that help the testes produce testosterone. Elevated levels of estrogen can even produce “man boobs,” with male breast tissue growing.