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How TRHR Variants Affect Lean Body Mass: What Your Genotype Means

Lean body mass includes all the weight in your body except fat, such as muscles, bones, organs, and fluid. It plays a key role in metabolic rate, strength, balance, mobility, and long term health. The TRHR gene helps regulate the thyroid hormone signaling pathway, which influences metabolism and muscle physiology. Variations in TRHR can subtly change how your body builds and maintains muscle and how it responds to diet, exercise, and thyroid-related nutrients.

How to Think About Genetic Predisposition

Your genotype gives insight into a natural tendency, not a certainty. Genetics can nudge how easily you gain or keep lean mass, but lifestyle choices are usually the dominant factor. Proper nutrition, resistance training, sleep, stress management, and addressing thyroid health when needed can greatly modify outcomes regardless of genetic background.

Practical Strategies to Support Lean Body Mass

  • Protein intake: Aim for adequate protein distributed across meals to support muscle protein synthesis. For many adults who are active or who want to build/retain muscle, 1.2 to 2.0 grams per kilogram body weight per day is a useful range. Include complete proteins such as lean meats, fish, eggs, dairy, soy, or combinations of plant proteins.
  • Resistance training: Progressive resistance exercise is the most reliable way to increase and preserve lean mass. Focus on compound movements that target large muscle groups, and aim for at least two to three sessions per week with gradual increases in load, volume, or intensity.
  • Thyroid-supporting nutrients: Iodine and selenium are important for thyroid hormone production and regulation. Ensure dietary sources such as iodized salt, seafood, dairy, and selenium-rich foods like Brazil nuts, fish, and whole grains. Avoid excessive supplementation without medical guidance.
  • Calorie balance: To build muscle, a modest calorie surplus combined with resistance training is usually needed. To preserve lean mass while losing fat, prioritize high protein intake and resistance exercise during a calorie deficit.
  • Sleep and recovery: Aim for consistent, sufficient sleep and include rest or active recovery days in your training plan. Sleep supports muscle repair, hormone balance, and metabolic health.
  • Stress management: Chronic stress and elevated cortisol can interfere with muscle maintenance and recovery. Practices such as mindfulness, breathing exercises, and regular activity can help manage stress.
  • Medical oversight: If you have symptoms of thyroid dysfunction or other health issues that affect weight or muscle, discuss them with your healthcare provider. Thyroid function tests can clarify whether intervention is needed.

Supplement Considerations

  • Consider vitamin D if levels are low, as vitamin D supports muscle function and overall health.
  • Protein supplements such as whey or plant-based powders can help reach daily protein targets when whole foods are insufficient.
  • Creatine monohydrate is a well-studied supplement that can enhance strength and lean mass gains when combined with resistance training.
  • Only use iodine or selenium supplements under the advice of a clinician, especially if you have existing thyroid conditions.

Genetic Interpretation: TRHR rs16892496

Two effect alleles (GG): Higher lean body mass tendency

If your genotype is GG for rs16892496, you carry two copies of the effect allele associated with higher lean body mass. TRHR influences thyroid hormone signaling, which affects muscle metabolism and growth. This genotype suggests a natural advantage for building and maintaining muscle tissue.

What this may mean for you

  • You may find it easier to gain or retain muscle compared with average.
  • Strength training may give relatively strong returns, so prioritize progressive overload and targeted resistance programs.
  • Recovery and adequate protein intake are important to maximize this advantage.

Actionable recommendations

  • Follow a structured resistance training plan 3 to 5 times per week, including compound lifts and progressive increases in load.
  • Aim for protein in each meal. For muscle-focused goals, consider 1.4 to 2.0 g/kg body weight per day depending on activity level.
  • Include iodine and selenium rich foods to support thyroid function; only supplement if tests or a clinician indicate a need.
  • Consider creatine supplementation if appropriate for your goals to boost strength and lean mass gains when combined with training.
One effect allele (GT): Intermediate lean body mass tendency

If your genotype is GT for rs16892496, you carry one copy of the effect allele and have an intermediate genetic predisposition for lean body mass. TRHR-related signaling likely supports moderate muscle and metabolic potential.

What this may mean for you

  • You may build or maintain muscle at an average rate compared with the general population.
  • Lifestyle factors such as diet quality, training consistency, sleep, and stress management will strongly influence outcomes.

Actionable recommendations

  • Commit to regular resistance training 2 to 4 times per week with gradual progression and adequate recovery.
  • Ensure sufficient daily protein intake. Distribute protein across meals to support muscle repair and synthesis.
  • Support thyroid health with dietary iodine and selenium sources and monitor symptoms of thyroid imbalance with your clinician.
  • Use evidence based supplements such as protein powders or creatine if training goals require them, following guidance from a healthcare professional.
Zero effect alleles (TT): Typical lean body mass tendency

If your genotype is TT for rs16892496, you carry two copies of the non-effect allele and have a typical genetic predisposition for lean body mass. TRHR function is likely within the common range for influencing thyroid signaling and muscle-related outcomes.

What this may mean for you

  • Your capacity to build or maintain muscle is consistent with average expectations.
  • Behavioral factors will largely determine your ability to change body composition.

Actionable recommendations

  • Adopt a consistent resistance training program and progressive overload to stimulate muscle growth and preservation.
  • Consume adequate protein and prioritize nutrient-dense foods to support recovery and metabolic health.
  • Maintain sleep quality, manage stress, and include thyroid supporting nutrients in your diet as part of an overall healthy lifestyle.
  • If you have concerns about thyroid function, consult your healthcare provider for appropriate testing and management.

When to Talk to Your Healthcare Provider

  • If you have unexplained changes in weight, persistent fatigue, hair loss, or other symptoms that could suggest thyroid dysfunction, arrange medical evaluation.
  • If you are considering high dose supplements, hormone therapy, or major changes to your exercise or diet because of genetic results, consult a clinician or registered dietitian first.
  • Use genetic information as one piece of the puzzle. Clinical tests and a medical history are essential to guide personalized care.

PlexusDx provides educational information on genetic predispositions only. This content is not medical advice. Always consult a qualified healthcare professional before making decisions about medical care, diagnosis, or treatment.