Biomarkers to inform a precision nutritional plan

Many diets involve calorie counting and selecting foods based on protein, fat, and carbohydrates. However, too many people find losing weight on these diets challenging because they are not tailored to their personal profiles. In this blog, we consider a few markers and measures that may help guide people's dietary choices.

Smoothie tapper

Too many diets, too little time

While diets for generalized populations may work in an averaging sense by simply monitoring calorie intake, many people on these plans realize that they need to personalize a mix of nutritious food types to suit their tastes (more palatable choices) as they pursue their health and weight goals. More recent work has pointed to tailoring diet type to body type or body chemistry. However, for the best nutritional health, many researchers have pointed out that the mix of protein, carbohydrates, and fats can be tailored to body types.

Not only is the proper mix of protein, carbohydrates, and fats critical to each of these, but the subcategories of these food types are also important. In general, foods rich in vitamins, minerals, and fiber, as well as those with omega-3 or omega-6 fatty acids, are healthy choices; foods with complex carbohydrates are generally better than those with simple carbohydrates (sugars); and lean meats or fish are better choices than so-called marbled cuts.

So the question is - how can you pick the best diet to have a healthy lifestyle?

Body types

One approach is to start with broad body-type diets, then become more selective for an individual’s health profile. For example, a diet for a mesomorph body type (mid-range BMI, between 17 and 25) would do best with a well-balanced meal plan of 30% protein, 40% carbs, and 30% fat. Diets could be designed for a mix of whole grains and starchy carbohydrates, healthy fats, and protein-rich foods.

For an ectomorph with a naturally fast metabolic rate (low BMI, less than 17), a good starting macronutrient ratio would be 25% protein, 55% carbohydrates, and 20% fat.

An endomorph (high BMI, greater than 25) should consume a higher proportion of protein and fewer carbohydrates. A diet with 35% protein, 35% fats, and 30% carbohydrates would be the most appropriate for individuals with this BMI. Note that an individual with a BMI greater than 30 is considered medically obese.

Markers from established clinical blood tests

Beyond these macroscopic measures, many markers have been identified as general indicators of good health. Biomarker utility is inferred through their impact on metabolic and lipid panels in standard clinical blood tests (e.g., the effect of a lower-fat diet on blood cholesterol levels). In combination, these tests provide a snapshot of an individual's state of health.

Standard metabolic and lipid clinical panels represent primary nutritional markers, and clinicians use them as the biomarkers that inform an individual’s choice of a diet plan. Markers of interest present in standard clinical laboratory blood tests include:

  • glucose and hemoglobin A1c
  • lipids (high-density and low-density lipoprotein cholesterol, triglycerides);
  • thyroid stimulating hormone (TSH) levels. 

Each marker provides a critical measure of one’s overall health and lifestyle control over metabolism and energy levels. The range of markers measured over time (i.e., longitudinally, such as annually or semi-annually) is of particular value in correcting or fine-tuning a diet plan.

Markers of metabolic regulation

One family of markers frequently measured but not often considered in this context is the thyroid hormones. These hormones function to regulate metabolism, accomplished through an interconnected feedback loop. The loop starts with the release of thyrotropin-releasing hormone (TRH) by the hypothalamus, the so-called gatekeeper between the gut and the brain. TRH stimulates the pituitary gland to secrete TSH, which, in turn, stimulates the thyroid gland to produce thyroid hormones thyroxine (T4) and triiodothyronine (T3). The interplay among these hormones ultimately regulates an individual’s metabolism - a regulation signature unique to each person.

To regulate metabolism effectively, the body monitors TRH, T3, and T4 levels and consequently releases TSH in the necessary concentration to meet the body’s energy needs. High TSH levels typically indicate that the thyroid is not producing enough T3 and T4 thyroid hormones (underactive thyroid or hypothyroidism), which can lead to a slower metabolism. Hypothyroidism correlates with hypometabolism, lower T3 and T4 levels, higher TSH levels, and hyperglycemia.  

Conversely, low TSH levels may indicate an overactive thyroid (hyperthyroidism), where the body produces too much thyroid hormone, increasing your body’s metabolism. An overactive thyroid, also known as hyperthyroidism, can indicate hypermetabolism, higher levels of T3 and T4 hormones, lower TSH levels, and hypoglycemia.

 In short, lower TSH (thyroid-stimulating hormone) levels correlate with higher metabolism (and, conversely, higher TSH with lower metabolism).

A product with the trade name SYNTHROID® (levothyroxine sodium) may be prescribed for hypothyroidism. The drug effectively replaces or supplements a hormone usually made by the thyroid gland to regulate (i.e., speed up) metabolism.


Metabolites measured in a basic metabolic panel are selected to determine general health. Doctors and clinicians use them to assess different health conditions that may be managed through medication (if needed), diet, exercise, and developing a sleep regimen. Thyroid hormone measurements are a separate set of clinical blood tests that can determine if a person is hyper- or hypo-metabolic, impacting your well-being. By monitoring and treating these conditions holistically, one can develop a treatment plan for a healthy lifestyle. Each treatment should be specific to an individual’s profile and managed through periodic prescribed blood tests and the advice of a medical professional. 


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