I think just about everyone is aware that an under-active thyroid can result in weight gain and difficulty in losing weight. The fact is that there are many other organs of the endocrine system that play a role in body fat metabolism. It is now known that bone is an endocrine organ. The endocrine system is the collection of glands that secrete hormones into the blood that regulate the function of distant tissues in the body. The thyroid, for example, secretes thyroxine (T4) and triiodothyronine (T3), hormones that activate genes in cells throughout the body and result in increased metabolic rate and heat production. This translates into weight loss. Bone also secretes hormones. Bone is not simply like a piece of chalk. Bone contains not only calcium and other minerals but structural protein and cells. Bone cells produce a number of important messaging substances. Osteocalcin is a bone-derived protein that is released into the blood stream and has diverse important effects on several tissues and physiological functions. Osteocalcin, which is produced by bone-building cells called osteoblasts, has a positive effect on the beta cells of the pancreas. It increases proliferation of the beta cells. Beta cells produce the hormone insulin, which plays a critical role in blood sugar regulation, nutrient uptake by the cells, mitosis or cell division, and other important functions. Osteocalcin also has a positive effect on another insulin-related hormone: adiponectin. Adiponectin is a hormone produced by fat cells. People who are obese don't make adequate amounts of adiponectin. Adiponectin plays an important role in insulin sensitivity - it improves how muscle and other cells respond to insulin's signal. It inhibits sugar production by the liver. Adiponectin stimulates fatty acid oxidation or the burning of fat. Adiponectin is also anti-inflammatory.  The net effect of osteocalcin in regard to body fat is reduced appetite, improved blood sugar and insulin metabolism, reduced inflammation, and weight loss.
In a study of 2493 people, higher blood levels of osteocalcin were associated with higher adiponectin levels. Osteocalcin was negatively associated with blood glucose, insulin, triglycerides, leptin, insulin resistance, body mass index, and the metabolic syndrome. In a favorable feed-forward cycle, adiponectin increases proliferation of the osteobalsts or bone-building cells. Higher adiponectin levels would be expected to strengthen bone and lead to even more adiponectin production. Bone produces another hormone that helps with weight loss: bone morphogenetic protein 7. This hormone stimulates the production of brown adipose tissue. Why is that good? Brown adipose tissue is a "good" type of fat. It is found in small amounts in the body compared to the major storage form of fat, which is white adipose tissue. Brown adipose tissue is very metabolically active. It induces thermogenesis or the production of heat from burning calories. So, if you want to be more successful at losing fat, don't forget your bones. Healthy bones will aid fat loss while unhealthy bones will slow fat burning. Some of the important influences on bone health include exercise, vitamins D & K, calcium, magnesium, strontium, berberine, and creatine. Proper hormone balance is important. A whole-foods, unrefined, phytochemical-rich diet, which is alkaline-forming and anti-inflammatory is critical for healthy bones. The Mediterranean -style diet, which I use with my patients, fits this description. Saleem U, Mosley TH Jr, Kullo IJ. Serum osteocalcin is associated with measures of insulin resistance, adipokine levels, and the presence of metabolic syndrome. Arterioscler Thromb Vasc Biol. 2010 Jul;30(7):1474-8. Epub 2010 Apr 15. | 
