Hyperthyroidism increases your metabolism, and many individuals initially have a lot of energy, according to the American Association of Clinical Endocrinologists. However, as the hyperthyroidism continues, the body tends to break down, so being tired is very common. It’s hard to resist snacks when you’re tired. Your body has no energy and thinks it’s hungry. Research has also shown that tired people tend to reach for foods that are high on bad carbs.