nutrition and health markers

A Nutritional Guide to Medical Checkups

In this article, I hope to explore common lab tests and health markers that might be part of a routine medical checkup. As I discuss each marker, I will briefly touch on the dietary “levers” one can pull to affect their health in positive ways.

An RD’s Guide to Medical Checkups

By: Jeremy Partl, Registered Dietitian

“How does a registered dietitian think about the concept of health?” That is a question that I could go on about for days and days.

What “health” means is a little bit of an open question. It may mean something a little bit different to me than to you. Recently, Barbell Logic published an ebook on health and lifting that gave this definition:

“The qualities of health include not just the absence of disease, but also those qualities that allow you to live well, be productive and independent, and to fare better in case of illness or injury.”

This is a good, general definition that covers why many people train for strength, but it does not cover the “nuts and bolts” of health markers—the things your doctor is looking at when you go for a checkup. One of the most common things that I get asked is about the connection between those health markers and other common measurements of health and what we eat.

In this article, I hope to take you on an explorative journey of common lab tests and markers that might be part of your routine medical checkup. As I discuss each marker, I will briefly touch on the dietary “levers” one can pull to affect their health in positive ways.

As a note, nothing in this article should be taken as medical or dietary advice of any kind. The suggestions are general and based on existing research and my own experience. You should discuss all issues, concerns, and treatment possibilities with a medical professional.

Body Weight Measurement

Our society is fixated on weight. Whether it is waking up every morning and stepping on the scale or the first thing you do when you go to the doctor, weight measurement has become a heavy hitter when it comes to assessing health.

Obesity is a significant risk factor for and contributor to increased morbidity and mortality from numerous chronic diseases and ailments such as cardiovascular disease, cancer, osteoarthritis, liver and kidney disease, sleep apnea, and depression.[1] Obesity may also reduce one’s overall quality of life to a significant extent.

Probably the most recognized measure outside of just pure, scale weight is the Body Mass Index (BMI). It is a calculation based on weight and height that is supposed to be a quick tool to assess weight-related health risks.

However, there are clinical limitations of BMI. The BMI does not distinguish between excess fat, muscle, or bone mass, nor does it provide any indication of the distribution of fat among individuals. Factors such as age, sex, ethnicity, and muscle mass can influence the relationship between BMI and body fat.[2]

The following are some examples of how certain variables can influence the interpretation of BMI:

  • On average, older adults tend to have more body fat than younger adults for an equivalent BMI.
  • On average, women have greater amounts of total body fat than men with an equivalent BMI.
  • Most notable for our readers, muscular individuals and highly-trained athletes may have a high BMI because of increased muscle mass.

The standard weight status categories associated with BMI ranges for adults are:


Weight Status

18.4 or Below Underweight
18.5-24.9 Healthy Weight
25.0-29.9 Overweight
30 or More Obese


A more helpful indicator is the Waist Circumference and Waist to Hip Circumference Measurements. Research suggests that the physical location of fat can dramatically influence chronic disease and metabolic risk.[3] For example, excess fat around the midsection can increase your risk of developing diabetes or heart and circulation diseases. Weight around the middle usually means that there is more fat near the internal organs, which might influence the way they function.[4]




Moderate Risk

High Risk

Waist Size Men 37 in (<94 cm) 37-40 in (94-102 cm) 40 in (≥102 cm)
Women 31 ½ in (<80 cm) 31 ½ -34 in (80-88 cm) 34 in (≥88 cm)
Waist to Hip Ratio Men <0.9 0.9-0.99 ≥1.0
Women <0.8 0.8.-0.89 ≥0.9


Dietary Leverages to Normalize

  • Start food journaling to bring awareness to how much you are eating, patterns with intake, etc.
  • Potentially implement tracking your calorie and macronutrient intake to become more aware and in control of how much you are eating.
  • Emphasize protein intake, which has the largest impact on keeping hunger at bay, retaining muscle mass, and is the most thermogenic.
  • Choose higher volume, high-fiber foods like non-starchy vegetables, high-fiber fruits, beans and legumes, popcorn, etc. to fill the stomach, slow digestion, and keep you full for hours. A good strategy to start with is to fill half your plate with non-starchy vegetables at each meal.
  • Eat solid foods instead of drinking your calories, and limit/eliminate calorie-containing beverages.
  • Make sure you are drinking adequate water. A good rule of thumb is to drink enough water to make and keep your urine pale yellow to clear.
  • Use smaller utensils and eat from smaller plates to help you unconsciously eat less.
  • Eat distraction-free, slow down, and cue into hunger/fullness cues throughout the meal.

Heart and Circulatory Health

Hypertension or high blood pressure is one of the most common medical concerns impacting millions of people. High blood pressure increases the risk of heart disease and stroke, two leading causes of death for Americans.[5] Blood Pressure can reveal how well your heart and blood vessels are working, measuring the force of blood against your artery walls while your ventricles squeeze and push blood out to the rest of your body (systole) and the force of blood against your artery walls as your heart relaxes and the ventricles are allowed to refill with blood (diastole).[6]

Although there are rarely any signs of high blood pressure (which is why it is called the “silent killer”), if left untreated, the heart gradually becomes enlarged and less efficient. Over time, this can damage the blood vessels, kidneys, eyes, and other parts of the body. In addition, as blood pressure goes up, artery walls become thicker, stronger, and narrowed and can threaten to slow or stop blood flow.[7]


Blood Pressure Category

Systolic mm Hg (upper number)

Diastolic mm Hg (lower number)

Normal Less than 120 Less than 80
Elevated 120-129 Less than 80
High- Stage 1 130-139 80-89
High- Stage 2 140 or higher 90 or higher


The simplest measurement of cardiovascular health may be your heart rate, or how many times your heart beats per minute. The rate varies considerably from person to person, depending on a number of factors such as level of activity, stress, emotion, age, medications, and more, but in general, a lower heart rate implies more efficient heart function and better cardiovascular fitness.[8]


Heart Rate (beats per minute)



100 or above Above Normal May be normal for very sedentary adults, but pairs with other health problems
60-100 Normal Considered to be typical for most averagely healthy adults
40-60 Slightly Low May be normal and is very typical of fit adults
40 or below Very Low May be normal for very fit adults, but also may be an indicator of heart or circulation problems


At least once a year as part of a primary care checkup, individuals will most likely get their blood lipids tested. A Blood Lipid Panel is used to assess your risk of cardiovascular disease and to monitor the treatment of unhealthy lipid levels.

Most lipid panels will measure a minimum of cholesterol, triglycerides, High-density lipoprotein (HDL), and Low-density lipoprotein (LDL).

While often demonized, cholesterol plays a vital role in many body functions, such as making hormones, producing bile to help digestion, and keeping cell membranes flexible. Cholesterol is carried in the blood attached to lipoproteins, with the main ones being HDL and LDL. HDL helps to remove cholesterol from fatty plaques on the artery walls and carries the cholesterol to the liver for removal from the body, which is why it is known as the “good” cholesterol. LDL, on the other hand, carries cholesterol from the liver to body cells and can deposit some of that cholesterol on artery walls, forming fatty plaques that reduce blood flow, which is why it is referred to as “bad” cholesterol. Triglycerides are a type of fat in the bloodstream that are created when you eat an excess of calories, which is why high levels of triglycerides are typically associated with obesity and an increased risk of cardiovascular disease.[9]

Below are a few of the standard guidelines for lipid panels to give you an indication of cardiovascular health and the risk of cardiovascular disease.[10], [11]



Optimal or Desirable

Near/Above Optimal

Borderline High


Very High

Total Cholesterol (mg/dL) <200 200-239 >240
Fasting Triglycerides (mg/dL) <150 150-199 200-499 >500
LDL Cholesterol (mg/dL) <100 100-129 130-159 160-189 >190



HDL Cholesterol

Low Level, Increased Risk

Average Level, Average Risk

High Level, Less than Average Risk

Women <50 mg/dL 50-59 mg/dL mg/dL
Men <40 mg/dL 40-50 mg/dL 60 mg/dL





Total Cholesterol: HDL Ratio Above 4 Under 4


Dietary Leverages to Normalize

Diets high in total fat intake may still be neutral or cardio-protective, depending on the sources and composition of that dietary fat.[12]

  • Keep your diet low in saturated fat (< 10% of calories) by excluding and moderating things like whole-milk dairy products, red meat, coconut oil, butter, etc.
  • Emphasize a diet predominantly from unsaturated fats like fish oils, olive oil, nuts, etc.
  • It can still be helpful to lower overall fat and calorie intake by choosing lean sources of protein like skinless poultry, extra-lean ground beef and turkey, egg whites, etc.
  • Focus on including a higher amount of dietary fiber and reducing free sugars/refined carbohydrates by focusing on whole grains, beans, legumes, non-starchy vegetables, etc.
  • Choose foods with less sodium and prepare foods with little or no salt. Thoroughly rinse and drain canned goods that are high in sodium.
  • If you drink alcohol, drink in moderation. That means no more than one drink per day if you’re a woman and no more than two drinks per day if you’re a man.

Blood Sugar Management

As the American population has shifted into a more sedentary lifestyle, and the Westernized diet has proliferated over the last 20 years, the number of adults diagnosed with diabetes has more than doubled.[13] Diabetes, particularly Type 2 Diabetes, is a chronic disease indicative of poor blood sugar management. Maintaining the correct blood glucose level is essential for the proper functioning of the body. However, it often is compromised as we age and adopt a Westernized lifestyle.

The most typical test to monitor blood sugar management is a Fasting Blood Glucose Test. This test measures the level of sugar in the bloodstream after at least an 8-hour period of fasting.



High Risk (“Pre-Diabetes”)


Blood Sugar (mg/dL) <100 100-125 >125


Unlike a glucose test, which provides information strictly at the time of testing, the Hemoglobin A1c (HbA1c) or Glycosylated Hemoglobin Test reflects a picture of blood sugar over the last 2-3 months. In the blood, glucose joins to hemoglobin (the oxygen-carrying component of blood). This test is not impacted by recent food intake and gives an overall picture of long-term blood glucose control.



High Risk (“Pre-Diabetes”)


HbA1c <5.7% 5.7-6.4% ≥6.5%


Dietary Leverages to Normalize

  • Start to monitor how many carbohydrates you are consuming throughout the day. You don’t have to go low carbohydrate to control your blood sugars, but your diet shouldn’t be primarily carbohydrates. A simple model to start with is about 1/2 of your plate coming from non-starchy vegetables and 1/4 of your plate coming from protein and the remaining 1/4 of your plate from fruit or starchy carbohydrates.
  • Reduce and/or eliminate sugar-sweetened beverages in your diet.
  • Increase the number of high-fiber carbohydrates (vegetables, legumes, fruits, whole grains) that you are eating and reduce the amount of processed, refined carbohydrates you are eating.
  • Pair carbohydrate-rich meals and snacks with protein and fat to slow down digestion and avoid large fluctuations in blood sugar.
  • Place the majority of your carbohydrates before and/or after your training sessions and when you are most active.

Liver Function

Alanine transaminase (ALT) and Aspartate transaminase (AST) are two important enzymes that often are used to assess the health of the liver. When the levels of these enzymes are raised, it’s a signal that the liver cells may be damaged or inflamed.

Liver function tests can be transiently impacted by intense exercise, both running and resistance training, and were shown in one study to significantly increase the enzymes for at least seven days, even in trained athletes.[14]

The sad thing is that there really is not anything nutritionally that you can do to prevent elevations in these enzymes as a result of being active. While your MD may have concerns, when put into context, it’s likely not a major issue. If one or both of these transaminases tests are high and you are curious about its origin, take a week or two off from hard training and have your blood re-tested.

Kidney Function

As the key components of the urinary system, the kidneys have two main jobs: filtering waste products and regulating fluid balance. Problems with kidney function can affect vital body processes, as well as interfering with the excretion of waste.

One important marker is Blood Urea Nitrogen (BUN), which is a measure of nitrogen in your blood that comes from the by-product of protein metabolism by your body. If your kidneys are not able to remove urea from the blood normally, your BUN level rises.

While this may be of concern for the Average Joe who eats the standard Western diet and is sedentary, things change for people consuming high-protein diets because they are resistance training. Increased urinary excretion of urea nitrogen might be due to the high rates of protein metabolism that follow high-protein intake and muscle turnover (due to exercise).[15]

Another important compound, creatinine (which is a by-product of creatine phosphate), can be high and associated with urinary tract infections, reduced renal blood flow, and acute kidney damage.

But, it’s important to consider context once again.

There are multiple factors related to active populations that can lead to a rise in creatinine, including increased muscle mass (creatinine production is directly proportional to muscle mass), increased protein consumption, consumption of creatine and protein supplements, and intense exercise.[16], [17], [18]

With all of this in mind, it’s important to consider other confounding factors if your doctor is concerned and you have a relatively decent lifestyle. Just like with the liver tests, you may be wise to lower your protein intake, take off from intense exercise for a while, and/or stop supplementing with creatine if you are really concerned.

Other Important Lab Tests

When it comes to weight management and maintaining a high quality of life, our thyroid glands are very important for regulating metabolic processes and our energy levels. For example, when your levels of thyroid hormones are above normal (hyperthyroidism), it can result in an increased resting energy expenditure and weight loss. On the other hand, hypothyroidism—lower than normal—can result in reductions in resting energy expenditure and weight gain. Both of those conditions come with other notable side effects, such as energy levels, mood, temperature regulation, and other quality of life factors.[19]

While most doctors will only routinely measure Thyroid Stimulating Hormones (TSH), a full thyroid hormone panel contains other important markers such as total and free T4, total and free T3, and reverse T3.[20]


Lab Test

Normal Range

TSH 0.5 to 5.0 mIU/L
Free T4 0.7 to 1.9ng/dL
Total T4 5.0 to 12.0μg/dL
Total T3 80-220 ng/dL


While there are a lot of factors that can contribute to abnormal thyroid levels (autoimmune diseases, tumors, etc.), we also know that certain nutrient deficiencies—caused by excess stress, poor dietary choices, medication, or hormonal birth control—can be contributing factors.[21]

Dietary Leverages to Normalize

  • Avoid being in a caloric deficit for a prolonged amount of time, or too frequently.
  • Eat a nutrient-dense diet that includes a variety of sources that contain selenium, iodine, vitamin D, zinc, magnesium, essential fatty acids, iron, and vitamin A. Good sources include swiss chard, wild sardines, spinach, sweet potatoes, bone broth, any lean protein source, and strawberries.
  • Eat organic when possible. Since a lot of the chemicals used to grow our foods are disruptors to our endocrine system, it may help to eliminate some of the toxins and pollutants.
  • Go easy on soy, cassava, cabbage, cauliflower, and broccoli. These are all examples of foods that can hinder the absorption of key hormones, vitamins, and minerals.
  • Consume quality probiotics with fermented vegetables and probiotic supplements to help your gut thrive.

Another interesting factor to reference when it comes to whole-body health is Creatine Kinase. It is an enzyme that is released by the heart, kidneys, skeletal muscle, brain, and other tissues that may be indicative of heart attack, kidney injury, and muscular dystrophy if high.

However, for most lifters, it may mean they had a hard workout or a few hard workouts before the blood test. The most recent review on the topic reports an average increase of 2.5-4.5 times pre-exercise levels, ranging from 400-700 U/L.[22] It should only be of major concern if levels are over 5,000 U/L, indicating a condition called rhabdomyolysis that IS a serious condition.


While this wasn’t an exhaustive list of the tests your doctor can order and the key markers that can be screened to assess health, hopefully it gives you a look into the metrics from the perspective of nutrition and how what we eat might affect what shows up in these common tests.


[1] Pi-Sunyer, X. (2009). The medical risks of obesity. Postgraduate medicine, 121(6), 21-33.


[3] Frank, A. P., de Souza Santos, R., Palmer, B. F., & Clegg, D. J. (2019). Determinants of body fat distribution in humans may provide insight about obesity-related health risks. Journal of lipid research, 60(10), 1710-1719.

[4] DK. (2020). MEDICAL CHECK-UP BOOK. Place of publication not identified: DK Publishing.

[5] Kochanek, K. D., Murphy, S. L., Xu, J., & Arias, E. (2019). Deaths: final data for 2017.

[6] DK. (2020). MEDICAL CHECK-UP BOOK. Place of publication not identified: DK Publishing.

[7] DK. (2020). MEDICAL CHECK-UP BOOK. Place of publication not identified: DK Publishing.

[8] DK. (2020). MEDICAL CHECK-UP BOOK. Place of publication not identified: DK Publishing.

[9]DK. (2020). MEDICAL CHECK-UP BOOK. Place of publication not identified: DK Publishing.


[11] DK. (2020). MEDICAL CHECK-UP BOOK. Place of publication not identified: DK Publishing.



[14] Pettersson, J., Hindorf, U., Persson, P., Bengtsson, T., Malmqvist, U., Werkström, V., & Ekelund, M. (2008). Muscular exercise can cause highly pathological liver function tests in healthy men. British journal of clinical pharmacology, 65(2), 253-259.

[15] Kim, H., Lee, S., & Choue, R. (2011). Metabolic responses to high protein diet in Korean elite bodybuilders with high-intensity resistance exercise. Journal of the International Society of Sports Nutrition, 8(1), 10.

[16] Samra, M., & Abcar, A. C. (2012). False estimates of elevated creatinine. The Permanente Journal, 16(2), 51.






[22] Giechaskiel, B. (2020). Weight training and creatine kinase (CK) levels: a literature review. Int J Sci Res IJSR, 9(1), 303-11.




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