Other symptoms include nervousness or irritability, fatigue or muscle weakness, feeling too hot, problems sleeping, shaky hands, a rapid and irregular heartbeat, diarrhea, and mood swings, the NIDDK says.
2. Persistent depressive disorder
Just as this condition can cause weight gain due to overeating, it can also cause weight loss due to undereating. If you’re grappling with this and other symptoms of persistent depressive disorder or depression, that’s definitely worth noticing.
3. Peptic ulcer disease
Like the condition above, this is on both lists because it can influence your eating habits in a number of ways. Some people find that eating actually makes the pain of peptic ulcers worse, Dr. Lowden says, so they might try to eat as little as possible and lose weight as a result.
You might already know that type 1 and type 2 diabetes happen when your blood sugar (glucose) levels are persistently too high, and that diabetes is often associated with obesity.
But diabetes can also cause weight loss, according to the Mayo Clinic, along with issues like increased thirst, peeing often, fatigue, blurry vision, and more. The weight loss comes into play if diabetes makes you pee frequently to get rid of excess sugar in your blood, which can also make you pee out calories, the Mayo Clinic explains.
5. Celiac disease
When you have celiac disease, eating gluten (a protein that’s found in wheat, barley, and rye) triggers a pretty gnarly immune response in your small intestine, according to the Mayo Clinic. Over time, this harms your small intestine’s lining and prevents absorption of nutrients, which can lead to weight loss.
This intestinal damage can also cause diarrhea, fatigue, bloating, anemia, and more, the Mayo Clinic says.
This actually isn’t a condition, it’s a collection of symptoms. If someone has dementia, neurological changes compromise their ability to think, remember, and reason as well as they used to, the National Institute on Aging explains. So, if someone has a form of dementia such as Alzheimer’s disease, they’ll go through behavioral and personality changes, along with other potential issues like unintended weight loss.
“They may simply forget to eat,” Dr. LePort says. “It may not even register sometimes that they’re hungry, or they don’t know what to do to resolve the issue.” They may also experience reduced smell and taste, trouble swallowing, and distraction while eating, according to the Mayo Clinic—all of which can contribute to weight loss.
7. Inflammatory bowel disease
Inflammatory bowel disease is a catch-all term for disorders that cause persistent inflammation in your GI system, the Mayo Clinic explains.
One of those disorders is Crohn’s disease. It causes hellish inflammation, typically in the last part of the small intestine and the colon, though it can affect any part of the GI tract, the Mayo Clinic explains. The inflammation frequently spreads deep into the layers of the bowel tissue. Then there’s ulcerative colitis, which is when you have inflammation and ulcers in the lining of your large intestine and rectum, the Mayo Clinic says.
Either type of inflammatory bowel disease can lead to symptoms like abdominal pain, severe and bloody diarrhea, fatigue, mouth sores, and a reduced appetite. Unsurprisingly, if you’re dealing with these symptoms, you’re probably going to lose weight, Dr. LePort explains.
8. Addison’s disease
This lesser-known disorder happens when your adrenal glands don’t produce enough of the hormones cortisol and aldosterone, the Cleveland Clinic says. These hormones influence almost every organ and tissue in your body, according to the Mayo Clinic, and signs that something’s up with them include abdominal pain, abnormal periods, cravings for salty foods, dehydration, depression, diarrhea, loss of appetite, nausea, sensitivity to cold, vomiting, and unexplained weight loss.
The weight loss occurs due to a portion of your adrenal glands called your cortex, the Mayo Clinic explains. The cortex is the outer layer of these glands, and it produces a group of hormones called corticosteroids. Corticosteroids include glucocorticoids, which influence your body’s ability to convert fuel from the food you eat into energy. Without sufficient glucocorticoids, your body has trouble properly utilizing the nutrients you eat, which can lead to weight loss. (As can the nausea, vomiting, and loss of appetite.)
So, when do you see a doctor about unexpected weight gain or loss?
It’s normal for your weight to fluctuate a bit from day to day, or even from morning to night. But a fluctuation that keeps you in a general weight range is different from persistent weight gain or loss over time. If that’s what you’re noticing, it’s time to head to a doctor. That’s especially true if you’re dealing with significant weight changes along with any of the above additional symptoms indicating that something’s wrong.