Muscle loss
This can lead to unexplained weight loss and the major symptom is muscle weakness. Also, one of your limbs may even look smaller than the other. Muscle loss is common in people who don’t exercise or are bedridden. Fortunately, proper nutrition and exercise will reserve muscle loss.
Overactive thyroid
Hyperthyroidism, or overactive thyroid, develops when your thyroid gland makes too much thyroid hormone. These hormones control many functions in the body, including metabolism. If your thyroid is overactive, you’ll quickly burn calories even if you have a good appetite. The result can be unintentional weight loss.