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If your doctor says your iron levels are “normal” but you still feel tired or run down, your blood test results might reveal more complex information about your health. Blood tests can check for different types of anemia and provide clues about how your body uses important nutrients like iron, vitamin B12, and folate.
Living with obesity can affect blood test results. Obesity may lead to chronic inflammation or nutrient deficiencies, which can make your lab values look different compared to those of people without obesity.
Understanding what certain blood test results mean can help you and your healthcare team get a clearer picture of your overall health. In turn, you can work together to improve your energy and well-being.
Blood Test | What It Measures | What Low Results Might Mean | What High Results Might Mean |
Mean corpuscular hemoglobin concentration (MCHC) | The amount of hemoglobin in each red blood cell (RBC) | RBCs may have less hemoglobin, which can suggest iron-deficiency anemia. | RBCs may have more hemoglobin than usual, which can happen in conditions like macrocytic anemia, long-term alcohol use, or thyroid issues. |
Mean corpuscular volume (MCV) | The average size of your RBCs | RBCs may be smaller than normal, which is common with iron-deficiency anemia or thalassemia. | RBCs may be larger than normal, often due to vitamin B12 or folate deficiency, or conditions like liver disease. |
Everyone should get regular blood work as part of their routine healthcare. One of the most common lab tests used to check your overall health is called a complete blood count (CBC).
A CBC measures:
These measurements, called red blood cell indices, include several different tests. One is the mean corpuscular hemoglobin concentration (MCHC) test, which measures the average concentration of hemoglobin inside your RBCs. Hemoglobin is the protein that carries oxygen throughout your body.
Another important test, the mean corpuscular volume (MCV), shows the average size of your red blood cells. The normal MCV range is usually between 80 and 100 femtoliters.
Together, MCHC and MCV results help doctors diagnose different types of anemia and understand what might be causing them.
Anemia happens when your body doesn’t have enough healthy red blood cells to carry oxygen efficiently. This can leave you feeling tired, weak, or short of breath, especially after physical activity.
An MCHC blood test helps your doctor understand the average concentration of hemoglobin in each red blood cell. The typical MCHC range is about 32 to 36 grams per deciliter.
A low or high MCHC result isn’t always a cause for concern. Your healthcare provider will look at it alongside your other CBC results to understand what it might mean for your health.
A low MCHC means your red blood cells have less color than usual, which may be caused by iron-deficiency anemia, the most common type of anemia. A high MCHC is less common and may be linked to macrocytic anemia, a condition where red blood cells are larger than normal.
Elevated MCHC levels can be caused by long-term alcohol use, thyroid conditions, or side effects from certain medications or treatments, such as chemotherapy.
If your MCV is low, it means your red blood cells are smaller than normal. This can be a sign of iron-deficiency anemia. It occurs when your body doesn’t have enough iron to make healthy red blood cells.
Another possible cause is thalassemia, an inherited blood disorder that reduces the body’s ability to produce healthy red blood cells and hemoglobin. This can lead to more severe forms of anemia.
If your RBCs are larger than normal, it may point to pernicious anemia — an autoimmune condition that prevents the absorption of vitamin B12 — or to other causes, such as celiac disease or Crohn’s disease. Large red blood cells can also be caused by folic acid deficiency anemia or liver disease.
Sometimes, anemia can occur even when your RBC size (MCV) is in the normal range. This is called normocytic anemia, and it can happen:
Understanding your MCHC and MCV levels can help explain how obesity-related inflammation may affect your red blood cells — and even mask signs of anemia.
When someone is living with obesity, their body often experiences chronic inflammation — a kind of ongoing internal stress that doesn’t fully go away. This inflammation prompts fat cells to release chemicals that tell the body to store iron instead of using it to make healthy RBCs.
When iron isn’t used properly, your RBCs may:
Inflammation can also cause your ferritin levels (a marker of stored iron) to appear normal or even high, even if your body doesn’t have enough available iron. This can hide true iron-deficiency anemia or make it look like a different kind of anemia on blood tests.
Obesity can sometimes lead to low nutrient levels because the body may not absorb or use certain vitamins and minerals efficiently. Some of these nutrients — especially iron, vitamin B12, and folate — are essential for making healthy red blood cells.
When levels of these nutrients are low, MCHC or MCV results may fall outside the normal range, increasing the risk of anemia.
Different nutrient deficiencies affect red blood cells in different ways:
Tracking your MCHC and MCV levels can help detect potential health issues early, even before symptoms appear.
Obesity and related factors, such as metabolic syndrome or bariatric (weight-loss) surgery, can change how your red blood cells look and function. These changes may hide or mimic signs of anemia, making it harder to detect with routine blood tests.
Metabolic syndrome is a group of health conditions — including high blood sugar, high blood pressure, excess abdominal fat, low “good” cholesterol (HDL), and high triglycerides — that together raise your risk of heart disease, type 2 diabetes, and stroke.
A diagnosis of metabolic syndrome is made when someone has at least three of these risk factors.
In metabolic syndrome, the body often experiences chronic inflammation, which can affect how red blood cells are made and how well they carry oxygen.
Research shows that in people with type 2 diabetes, MCHC levels tend to be higher, and MCV levels tend to be lower. This means their red blood cells may be smaller but more densely packed with hemoglobin.
These changes can make it harder for doctors to recognize iron-related anemia. Blood test results may look normal, even when the body isn’t getting or using enough iron effectively.
Bariatric surgery offers a powerful option for long-term weight loss, and it can also help improve or even reverse health conditions linked to obesity, such as type 2 diabetes, high blood pressure, sleep apnea, and joint pain.
These procedures change the stomach and/or intestines to reduce how much food you can eat or how well your body absorbs it. While this supports weight loss and can lead to improved energy and mobility, it also means the body may absorb fewer nutrients from food.
Over time, people who’ve had this surgery may not get enough:
These nutrients are essential for making healthy RBCs. A lack of them can lead to different types of anemia:
Sometimes, chronic inflammation and nutrient deficiencies happen at the same time. This can make blood test results harder to interpret, showing a mix of patterns that resemble different types of anemia.
Because more than one nutrient may be low at once, blood test results can look confusing or even “normal.” For example, a person with both iron and vitamin B12 deficiency might have red blood cells that appear average in size, even though both deficiencies are present.
Several factors can make it difficult to detect nutrient problems through blood tests:
That’s why doctors usually look at several blood test results together, instead of relying on just one number, to figure out what’s really going on.
For people living with obesity, tracking MCHC and MCV blood test results can give you and your healthcare provider valuable insight into your energy levels, nutritional status, and how your body is responding to treatment.
Regular testing can help identify potential problems early, before they start affecting your daily life.
If you’ve had bariatric surgery or are managing metabolic syndrome, these tests are especially important. They help ensure your body is getting the nutrients it needs to make healthy red blood cells and support overall well-being.
On MyObesityTeam, people share their experiences with obesity, get advice, and find support from others who understand.
Have you ever wondered if having obesity can change the size or color of your red blood cells? Let others know in the comments below.
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