Weight loss is a complex process, and many factors can contribute to a drop in weight. If you aren't actively trying to lose weight, or if you're losing weight too quickly, it could be indicative of a health condition and it's best to speak to a doctor.

Calorie Deficit

If you have recently lost weight unexpectedly, you might not be eating enough. If the calories you take in do not match the calories you are burning in your day-to-day activities, your body will respond by burning fat for fuel, which will cause weight loss.

Generally speaking, women should eat around 2000 calories daily, and men should consume about 2500. If you feel that calorie deficit may be the reason for your weight loss and you are already at a weight you and your physician consider safe, increase how much nutritionally dense, energy-rich foods you're eating. Nuts and seeds, avocado, and oily fish are excellent examples of calorie-dense, nutritionally rich foods.

woman checking the number of calories in her lunch


Poor Nutrition

Although eating unhealthy foods is often a cause of weight gain, poor nutrition can sometimes lead to weight loss instead. We need good quality fats and protein to build muscle and stay healthy, so a lack of these macronutrients in the diet can result in fat loss and muscle loss.

The likelihood of adverse effects from malnutrition increases with age but can be prevented with a whole-food diet full of healthy fats, protein, and carbohydrates.

dictionary definition of malnutrition



Stress is a common reason for weight loss, and it can take a while to recognize that our stress levels have increased. The main reason stress causes weight loss is a lack of appetite or loss of interest in food. However, a recent study also shows a brain chemistry link between stress and anxiety and weight loss, so even if you are eating well, chronic stress could lead to unexpected weight loss.

depressed or anxious woman lying in bed covering her face



Diabetes is a serious condition that affects the way your body uses food. The body can't use insulin effectively, meaning glucose cannot be used for energy. This results in fat and muscle being burned for energy instead, leading to weight loss.

Diabetes can cause serious health problems if left untreated, so if you think diabetes could be to blame for your unexplained weight loss, see your doctor for a glucose test.

doctor checking patient's blood sugar levels



Thyroid problems may cause weight gain or loss depending on whether they overstimulate (hyperthyroidism) or understimulate (hypothyroidism). Hyperthyroidism tends to cause anxiety and nervousness, irritability and anger issues, insomnia, and a rapid heartbeat.

There are several forms of hyperthyroidism, including auto-immune, but all forms can be life-threatening if untreated. Check with your doctor if you have other symptoms accompanying your weight loss.

doctor checking patient's thyroid



Depression is a possible cause of unexplained weight loss. People suffering from depression often have a reduced appetite or lose interest in their food. Unfortunately, this can lead to a vicious cycle where poor nutrition incites low mood, causing worsening symptoms of depression and further weight loss.

If you are suffering from low mood and weight loss, you should speak to a doctor. Effective treatments for depression include medication and therapy.

woman curled up sleeping depression concept


Gastrointestinal Disorders

Unexplained weight loss could indicate that your body is not digesting food properly. Weight loss can be a symptom of various gastrointestinal (GI) disorders, including celiac disease, Crohn's disease, and inflammatory bowel syndrome.

When GI disorders cause weight loss, it is usually accompanied by other symptoms such as diarrhea, vomiting, and bloating. If you have more than one of these symptoms, you may wish to see a gastroenterologist to rule out any GI disorders.

woman on couch experiencing extreme pain


Kidney Disease

Chronic kidney disease can be a cause of unexpected weight loss. Early-stage kidney disease often has very few symptoms, but lack of appetite and weight loss can be early indicators of decreasing kidney function.

If your weight loss is accompanied by a general feeling of ill health or fatigue, it is important to see a doctor, as other symptoms of kidney failure rarely appear until kidney function is extremely low, and early intervention is crucial to avoid the need for dialysis or transplant.

man undergoing dialysis for kidney disease



Weight loss is a common early symptom of human immunodeficiency syndrome (HIV). HIV can prevent the body from absorbing nutrients properly, which leads to weight and muscle loss. Other symptoms of HIV include swollen lymph nodes, fever, and night sweats.

HIV treatments have advanced enormously in recent years, so early detection can mean a fairly normal life. You should see your doctor for a blood test if you have other HIV symptoms alongside weight loss.

HIV/AIDS written on a paper with pills



People who have unexplained weight loss often worry that cancer may be the cause. Although there are many less serious, more likely causes, weight loss is often one of the first symptoms of cancer. There are several ways in which cancer could cause weight loss, including a tumor pressing on the digestive system and inflammation disrupting the hormones that regulate appetite.

Other early cancer symptoms include an unusual lump or swelling, general fatigue, and persistent bloating. Detecting cancer early is crucial for increasing the chances of survival, so if you are at all worried about your unexplained weight loss, it is best to see a doctor.

doctor giving patient news about medical health


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This site offers information designed for educational purposes only. You should not rely on any information on this site as a substitute for professional medical advice, diagnosis, treatment, or as a substitute for, professional counseling care, advice, diagnosis, or treatment. If you have any concerns or questions about your health, you should always consult with a physician or other healthcare professional.