N2 nicotinic receptors are found in the brain, plus the autonomic and parasympathetic nervous systems [1]. Different subunits make up these two types of nicotinic receptor, which is why we consider them separately. Muscarinic receptors have a different mechanism of action.
Your body weight can regularly fluctuate, but the persistent, unintentional loss of more than 5% of your weight over 6 to 12 months is usually a cause for concern. You should pay particular attention if you experience other symptoms, such as tiredness, loss of appetite and a change in your toilet habits.
Factors you can change: 1  Sex hormones. Low estrogen levels can cause bone thinning in women as can low testosterone levels in men. 2  Anorexia nervosa. This eating disorder can lead to bone loss. 3  Calcium and vitamin D intake. A diet low in calcium and vitamin D makes you more prone to bone loss. 4  Medication use.