22: The Importance of Lab Tests for Weight Management

Jul 17, 2023

Weight management is more than just calories in vs. calories out. Lab tests provide you with valuable insights into the intricate workings of your physiology, and ensure you get the strategies and interventions to best address your unique metabolic needs.

While I don't know what your medical history is or what your symptoms are, if weight is a challenge for you, today I want to discuss some things that should still be checked at the most basic level. This will also help to inform your future conversations with your own medical team.

CBC (Complete Blood Count) Test

This lets you know things like your hemoglobin count, which is what carries the oxygen around your body. It will also let you know things like platelet counts, and white blood cell counts. 

If your hemoglobin is low, that's a diagnosis called anemia. This is important because if you are starting out as anemic, you can be fatigued and have problems from that. And so knowing that your blood counts are where they should be is extremely helpful. A lot of women are really affected by their periods, and in the perimenopausal years, you might be bleeding more than normal. And so it becomes even more important that we know what the blood counts are doing. 

CMP (Complete Metabolic Panel) Test 

There is a difference between a basic metabolic panel, a BMP, and a CMP, which is a complete metabolic panel. I want you to get the one that's complete because this will include not only electrolytes (like sodium and potassium), but it will also include kidney function. What makes it the complete part, is that it has liver function as well, which is really important.

 Liver function really matters because one of the things that's extremely prevalent when weight is elevated even just a little bit.  Whenever liver numbers are up, that is always not a good sign and we really want to take action when we see that.

For most people, when the liver numbers start to increase, if it's weight related, there will not be any permanent damage in the liver. And so you might be told that if you can lose some weight, it will reverse the fatty liver, which is true. That is always easier said than done, but knowledge is power, so even knowing that this lab is up is extremely helpful.

Just like with blood sugar, this number is an indication to take action in your life. Especially in primary care, I would often see people who had five or six years of their liver numbers being up, and no action was ever really taken. They didn't really understand how significant it was.

With non-alcoholic fatty liver disease, where there's extra fat in the liver, it starts to scar with time, and that creates cirrhosis, which is a really serious liver condition that we can't reverse. That has been a reason that some people are needing liver transplants, just like someone that might have a history of alcoholism. Alcohol plays no part here, it’s just that weight has been up long enough where the liver can't handle all those fat stores in the liver.

Hemoglobin A1c Test

This is a three month average blood sugar number and a normal hemoglobin A1c is 5.6 or less. Pre-diabetic range is 5.7 - 6.4, and diabetes is at or above 6.5. This is important because by the time that this is showing up, you've likely not been in a great place metabolically for a long time.

Once the A1c starts to be in the pre-diabetic range, it’s time to take action. This is because if you can act when your blood sugar is in the pre-diabetic range, you are most metabolically flexible and you can turn it around to reversing it for life. 

You don't even need to lose weight to do this, you could just make nutrition changes to move more toward an unprocessed diet, work on blood sugar management, and start to incorporate some movement after meals to help bring down blood sugar. About one out of every three Americans is pre-diabetic, and if we can act when it's in this range, you can bring it down easier.

Fasting Insulin Levels

Fasting blood sugar levels under 100 milligrams/deciliter (mg/dL) are considered normal.

I would call 100 - 126 mg/dL impaired fasting glucose in the morning.

This is not something I checked as a primary care doctor, and I also don't really check it as a weight management doctor. Why? Because it doesn't change the management that I do. Personally, I am still going to work with you on how to have a balanced diet and approach to nutrition, and how to incorporate movement. It doesn't change anything I'm doing. 

For about 7% of people, even if their weight is up, that number is not going to be affected. That just means you are resilient at that moment. But for most people, when the weight is up, insulin levels have to be up to keep the blood sugar normal, even if you're not pre-diabetic or diabetic.

Fasting Lipid Panel

A lipid panel measures total cholesterol, LDL ("bad") cholesterol, HDL ("good") cholesterol, 

Triglycerides (another type of fat that causes hardening of the arteries).

What is fascinating with cholesterol levels in our body, is that they are usually not up in isolation. For example, a person with metabolic syndrome are likely to see triglycerides that are up, cholesterol levels that are up, high blood sugar, and high blood pressure. 

So cholesterol levels show us the patterns and the trends and prompt us to look into some of these other things too.

Basic thyroid testing

This could include a TSH level, which stands for Thyroid Stimulating Hormone, and that is the lab we check initially. Thyroid testing is important because I really consider the thyroid to be the master hormone regulator of our body, affecting all organ systems. 

This is going to affect our weight but mostly I do this test because people are going to feel poor energy-wise, they could be losing hair and if you're younger, your periods might be affected. Your heart rate can even be affected with this as well. So there are a lot of symptoms and they're usually very diffuse.

A lot of people want to know if their thyroid is the reason that their weight's up. I completely understand this but even if your thyroid function is found to be low, we see that there's actually not a lot of weight loss even on the medication for it. This is discouraging for people because they think they finally have the answer but usually it's not going to be the thing that leads to a lot of weight loss. 

Basic Vitamin Levels

When weight is elevated, people tend to be more deficient in vitamin D, and this also depends on where you’re living. The primary source of vitamin D in humans is sun exposure, which triggers synthesis of vitamin D in the skin. As many Americans avoid unprotected sun exposure due to concerns about skin cancer from UV radiation, many are not producing adequate levels of vitamin D.

Vitamin B-12 is another essential nutrient that many Americans may lack, since absorption problems are quite common–especially in older adults. B-12 deficiency can have very serious consequences, including anemia and neurological damage. 

Dietary wise, even if you don't have the problem right now, sometimes I see deficiencies develop further down the road, and so I'd like to know a baseline that these things were normal to begin with.

Get Dr. Rentea's newest free resource "What Labs to Consider Ordering in Weight Management" here.