Hint: It could indicate a breadth of health issues, but don’t panic yet.
Losing unintentional weight can feel pretty jarring—especially if it’s a significant amount all at once. And while it’s completely normal to fluctuate between a few pounds day to day, when you experience a bout of sudden weight loss, it can be a bit worrisome. Know that there are a lot of reasons for losing weight even when you’re not trying to, many of which are not serious.
Specifically, rapid weight loss can indicate a wide range of internal problems, such as mental health issues like anxiety or stress, autoimmune issues, thyroid imbalances, and more. It’s especially important for people with vulvas to take note of any rapid or unexpected weight loss, too, since it can cause hormone fluctuations in the body as well as changes in the menstrual cycle, explains
Erica Zellner, MS, LDN, a health coach at Parsley Health in California. Losing weight too quickly can also lead to a bunch of nutritional deficiencies, Zellner notes, and even correlates with drops in metabolism over time.
In short, there are a lot of factors that can be attributed to rapid weight loss.
Know that it’s completely normal to fluctuate anywhere from two to five pounds during any given week, Zellner says. Rapid weight loss, however, is generally considered losing more than 5 percent of your body weight over the course of six to 12 months, Zellner says.
Even if you are actually trying to lose weight, for whatever reason, one to two pounds per week is considered a safe rate of weight loss. “Losing more than that is considered too fast and could put you at risk of many health problems, including muscle loss, gallstones, nutritional deficiencies and a drop in metabolism,” Zellner says. Noted.
Unintentional weight loss can be related to a whole host of factors, not just what you’re eating every day.
“There are a lot of different reasons for unintentional weight loss, especially if you’re eating the same amount of food or exercising the same amount,” explains Linda Zhang, MD, a bariatric surgeon and associate professor of surgery at Mount Sinai Hospital in New York City. Those common issues include hormonal ones such as hyperthyroidism, autoimmune diseases, malabsorption intestinal issues, or even infectious diseases, explains Zhang.
If you’re concerned that you’re losing too much weight and you’ve already tried methods like increasing caloric intake or decreasing workouts to no avail, it’s time to see the doctor, Zellner says.
Also, unexplained weight loss tends to come with other symptoms such as irregular heart rate, excessive fatigue or thirst, increased anxiety or nervousness, tremors, menstrual changes, difficulty sleeping, and more, Zellner says. If you experience any of these issues alongside your unexplained weight loss, try to book an appointment with your physician to discuss.
Now, it’s time to get a little more specific about rapid weight loss and the causes behind it.
Yes, unexpected weight loss can in fact be a result of diabetes—both types. “The body is not able to gain energy from food because glucose is not able to get to the cells, and usually urinated out by the patient instead of absorbed,” explains Holly F. Lofton, MD, director of medical weight management at NYU Langone hospital. When high levels of glucose remain in the bloodstream instead of being absorbed, this leads to malnutrition, Dr. Lofton says.
Instead, your body is forced to obtain nutrients from the fat and muscles in your body, Zellner says, causing you to unexpectedly lose weight. Other symptoms of diabetes include extreme thirst and chronic fatigue, Zellner says, so if you’re experiencing these issues along with rapid weight loss, it’s time to head to the doctor.
At times, sudden weight loss can also be caused by hyperthyroidism (or Grave’s Disease) , a hormonal condition that can trigger metabolism issues such as overproduction of the thyroid hormone, Dr. Lofton says. “There’s a process in your body where your metabolism has changed so that you’re burning energy off more quickly,” says Dr. Lofton.
“This causes your body to burn more calories than it needs to and can result in weight loss,” Zellner says, making it so that your body burns its muscle and fat instead to obtain more calories. If you’re experiencing symptoms like excessive hunger or menstrual changes in addition to unexpected weight loss, head to the doctor for a check up.
Many cancers can cause weight loss because “cancer increases inflammation,” Zellner says. “This promotes muscle wasting and disrupts appetite-regulating hormones, and a growing tumor may also increase your resting energy expenditure,” she says. These factors can, in turn, result in unexpected weight loss, which is why it’s important to get checked if you feel that you’re not retaining weight.
Dr. Lofton recommends taking preventative measures by getting your regular cancer screenings such as cervical and breast exams, as well as lung scans and other risk assessments—especially if you’re over the age of 50.
“If you’ve traveled, especially internationally recently, you may be harboring a parasite,” says Zellner. (Two common ones are giardia and cryptosporidium.) "The parasite will cause malnutrition in the host which causes weight loss," Zellner says.
While this potential cause is uncommon, it’s always better to be cautious. If you’re also experiencing things like abdominal pain, bowel issues such as diarrhea, nausea, and vomiting, and the like, get your situation checked out by a doctor.
Depression, for some people, can actually cause a reduction in appetite, Zellner says. “And it can impact hormones like ghrelin, which is our hunger and satiation hormone.” If you’ve been feeling particularly down as of late, your unintentional weight loss could be a side effect of some ongoing and unaddressed mental health issues.
Other symptoms to look out for include feeling really down on a constant basis, feeling sad, having a loss of interest in your usual hobbies, fatigue, difficulty concentrating, irritability, and more, Zellner says.
While depression is one mental health issue that can result in unexpected weight loss, so is anxiety. An increase in anxiousness can cause an onslaught of health issues, Dr. Lofton says, including refraining from eating, appetite reduction, vomiting, and more—all of which can result in a loss of unexpected weight.
If you’ve experienced an increase in nervousness, anxiety, panic, and more, as well as unexpected weight loss, you might want to consider reaching out to a mental health professional to address your psychological and physiological predicament.
Sometimes losing unexpected weight is a result of muscle reduction as opposed to a loss of fat, which is something that can cause a bunch of problems for your health. “We want to avoid encouraging muscle loss in the body, which can happen when we’re losing weight too rapidly,” Zellner says. Losing your muscle mass can result in a breadth of issues like gallstones, nutritional deficiencies, and a slowed metabolism, Zellner notes.
Plus, unintentional muscle loss can be a sign of more serious issues like HIV, AIDS, or even congestive heart failure. If you’re feeling more fatigued, weakness, or you notice a disproportionate amount of muscle loss as of late, you’re going to want to get checked out by your doctor, Zellner says.
An issue related to your adrenal glands, Addison’s disease, also called hypocortisolism, is another issue that can bring about unexpected weight loss, Dr. Zhang says. This is when the adrenal glands do not produce enough cortisol, resulting in a slew of symptoms like skin tone changes, fatigue, dizziness, and unexpected weight loss.
Addison’s disease typically indicates an issue with the adrenal cortex, which is attached to your kidneys and helps regulate a great deal of your body’s functioning—including appetite. A decrease in appetite can, in turn, make you eat less, causing weight loss.
If you experience unexpected weight loss, it’s also important for you to double check the side effects of your various medications. “For example, Bupropion and other antidepressants are known to have weight loss as a side effect. Patients can start taking these for their mood disorders and have weight loss as a result,” says Dr. Lofton.
In short, if you experience sudden weight loss, you might want to double check the listed side effects of your various medications, even if you’re not taking any for mental health, specifically. If you want more specifics about the possible impacts of your medication, you can call your local pharmacist for more information.
The early aughts of celiac disease are often associated with a rapid decrease in weight, Dr. Lofton says. One aspect of celiac disease is that your body has a more difficult time absorbing nutrients which, in turn, can lead to malnutrition.
When your body experiences malnutrition, it’s forced to retrieve nutrients from other parts of your body such as your muscles and fat. This results in unexpected weight loss. If you’re experiencing other symptoms for celiac disease such as extreme bloating, gas, diarrhea, and constipation, Dr. Lofton says, it might be time to head to your doctor for a check-in.
Like celiac disease, stomach ulcers indicate a gastrointestinal issue where your body is unable to absorb proper nutrients, Dr. Lofton says.
“These usually come with signs such as diarrhea, problems swallowing, vomiting, and even bleeding,” Dr. Lofton says. Experiencing any of these additional warning signs? It might be time to chat with a doctor about checking for ulcers or other GI tract issues.
Otherwise known as chronic obstructive pulmonary disease, emphysema is the lungs have so much obstruction in the tissues that the body has to work very hard to take every breath, Dr. Lofton explains. The lungs become the primary organ and as a result, use up all the energy that could be going to other parts of your body, Dr. Lofton says.
“With COPD, the rest of the body just suffers and cells die because the lungs are using so much of the energy that’s produced,” Dr. Lofton says. Weight loss can indicate that you’re in the stages of severe COPD, and you might feel symptoms like discomfort eating, fatigue from cooking or preparing food, loss of appetite, and more.
“I think it’s important to mention substance abuse when it comes to unexpected weight loss,” Dr. Lofton notes. “When people drink alcohol or smoke tobacco, they’re sometimes not eating as much food, which can cause weight loss."
Amphetamines such as cocaine can also cause unexpected weight loss, since they largely suppresses appetite. Withdrawal from chronic cannabis use at times results in weight loss, too, since you might experience a decrease in appetite, Dr. Lofton says.
If you think recreational substance use might be the cause of your unexpected weight loss, try having an honest discussion with your doctor about your needs and whether regaining that weight is plausible for you.
Usually occurring after patients are prescribed steroids, an adrenal insufficiency can also lead to weight loss. “This usually occurs when a patient is prescribed steroids for a condition and then the patient stops taking the steroids, for whatever reason,” Dr. Lofton explains. So, the steroids interfered with your adrenal glands ability to function.
“The adrenal glands are present to help deal with stress, adjusting our blood pressure when needed if we stand up or sit down, and just kind of giving us energy to get through the day,” Dr. Lofton says. If the adrenal glands are not working properly, it can lead to primal adrenal insufficiency, which leads to weight loss as a result of malnutrition.
When it comes to congestive heart failure, the heart is having to work very hard in order to pump the blood throughout your entire body, even with medication use. “This is a tricky one, because the person can lose fat, but gain water, because a side effect is water retention,” Dr. Lofton says. “So your weight might not technically change,” Dr. Lofton notes.
Signs to look out for, however, are a thin face, sunken temples, bloated legs, and bloated stomach. If you experience any of these signs along with some unexpected weight loss, it might be a sign of congestive heart failure and you should go see a doctor.
Madeline Howard is a writer, editor, and creative based in Brooklyn. Her work has been published in Esquire, Nylon, Cosmopolitan, and more. Among other things, she was formerly an editor at Women’s Health. Subscribe to her newsletter ‘hey howie’ at madelinehoward.substack.com.
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