A gastric sleeve won’t directly "cure" your underactive thyroid (hypothyroidism), but it can help improve how your body responds to it. Since weight loss can enhance overall metabolic function, many people with hypothyroidism find that their symptoms improve after surgery. However, you’ll likely still need thyroid medication, but the dosage may need to be adjusted as you lose weight. Since hypothyroidism can slow metabolism and make weight loss more difficult, working closely with your doctor to monitor thyroid levels after surgery is important. Some people also experience better energy levels and fewer symptoms like fatigue once excess weight is lost.