Brief periods of generalized weakness are common,
especially after a strenuous workout or a stressful emotional situation, and
usually they just mean that you have overexerted yourself. Generalized weakness
is not a cause for concern as long as you are able to move all parts of your
body and complete your normal daily activities, even if you have to work a
little harder to get things done.
Weakness that does not have an
obvious cause, such as overexertion or a viral or bacterial illness, or that
does not get better or go away is more of a concern.
Problems with the thyroid gland,
which regulates the way the body uses energy.
A low thyroid level (hypothyroidism) can cause fatigue, weakness, lethargy,
weight gain, depression, memory problems, constipation, dry skin, intolerance
to cold, coarse and thinning hair, brittle nails, or a yellowish tint to the
A high thyroid level (hyperthyroidism) can cause fatigue, weight loss,
increased heart rate, intolerance to heat, sweating, irritability, anxiety,
muscle weakness, and thyroid enlargement.