Bloodwork for Fitness: Ferritin, TSH, and Testosterone Explained
Most people who get bloodwork done receive a report with values flagged as normal or abnormal against population reference ranges. These ranges are constructed from large general population datasets and are calibrated to identify pathology. They are not calibrated to identify performance gaps. A ferritin of 18 ng/mL is within the standard normal range. It is also a level at which most active individuals experience measurable fatigue, reduced VO2max, and impaired recovery. The lab report says normal. The body says otherwise.
Coach Aditya's approach to bloodwork: every key marker has a disease threshold, a normal range, and a performance optimal range. These three are different numbers. Understanding which zone your markers sit in changes the intervention completely. This article covers the five markers that most directly affect training and body composition results for active Indians.
What Blood Tests Should Active People Get and What Do They Cost in India?
The most informative panel for an active individual: complete blood count (CBC) including haemoglobin and MCV, ferritin, fasting glucose, fasting insulin, HbA1c, TSH, free T3, 25-OH vitamin D, total and free testosterone for men, and a standard lipid panel. For women add LH, FSH, and estradiol if cycle irregularities are present.
This panel costs approximately Rs 2,000–3,500 at most diagnostic labs in India including Thyrocare, SRL, Dr Lal PathLabs, and their franchises. It provides a comprehensive picture of the metabolic and hormonal factors that directly affect training capacity, fat loss rate, and recovery quality. Coach Aditya's recommendation: get this panel once before starting a structured programme and again every 6 months if you are actively working on a specific goal. The Bloodwork Analyzer tool takes your lab results and gives a coaching interpretation of what each value means for your specific goal.
What Is a Good Ferritin Level for Performance and Why Does It Matter?
Ferritin is the body's iron storage protein. It is distinct from serum iron and haemoglobin. You can have normal haemoglobin and low ferritin simultaneously, a state called iron depletion without anaemia. Most standard lab panels flag ferritin as deficient below 12–15 ng/mL. For athletic performance, this threshold is far too low.
Research consistently shows that ferritin below 30 ng/mL in women and below 40 ng/mL in men is associated with reduced VO2max, increased perceived exertion at submaximal exercise intensities, impaired recovery between sessions, and chronic fatigue. These effects occur in the absence of clinical anaemia. The person feels tired, trains worse, and recovers slowly while their haemoglobin looks completely normal on the lab report. Performance-optimal ferritin is 50–100 ng/mL.
Iron deficiency is particularly common in menstruating women (18mg daily requirement rising to 25mg in heavy flow), vegetarians and vegans (non-haem iron has 15–20% lower absorption than haem iron), and endurance athletes (foot-strike haemolysis and GI losses). If you are female, vegetarian, or training significant cardio volume and your energy and performance are below expectation, ferritin is the first marker to check.
What TSH Level Is Optimal for Fat Loss and Training Performance?
TSH (thyroid stimulating hormone) is the pituitary signal that drives thyroid hormone production. Higher TSH means the pituitary is working harder to stimulate a thyroid that is not producing enough. Standard reference ranges consider 0.5–4.5 mIU/L as normal. This range was constructed from population data including many people with subclinical hypothyroidism, which inflates the upper bound.
From a performance perspective, TSH above 2.5 mIU/L is associated with measurable reductions in TDEE, slower recovery, lower training energy, and impaired fat loss even when the value sits within the normal range. This is called subclinical or functional hypothyroidism. The thyroid is not failing by disease criteria but it is not producing enough active hormone to support optimal metabolic function. Free T3, the biologically active thyroid hormone, is more functionally relevant than TSH alone. Optimal free T3 is in the upper third of the reference range for your lab.
Prolonged aggressive calorie restriction is one of the fastest ways to suppress thyroid output. The body reduces T4 to T3 conversion as a metabolic conservation response. This is one mechanism of adaptive thermogenesis. If you have been dieting for 10+ weeks and fat loss has stalled, TSH and free T3 are worth checking before cutting calories further.
What Testosterone Level Matters for Men Who Train and How Do You Improve It?
Standard reference ranges classify below 300 ng/dL as hypogonadal. For active men, this threshold is too low to be meaningful. Testosterone below 400 ng/dL is associated with reduced muscle protein synthesis rate, lower training capacity, increased visceral fat accumulation, impaired recovery, and reduced motivation. Performance-optimal total testosterone for active men is 500–900 ng/dL.
Free testosterone matters as much as total. Sex hormone binding globulin (SHBG) binds testosterone and renders it biologically inactive. High SHBG can produce normal total testosterone with meaningfully low free testosterone. If total testosterone looks adequate but symptoms of low testosterone persist, check free testosterone and SHBG.
The most effective non-pharmacological interventions for testosterone optimisation: sleep of 7–9 hours is the single most impactful variable and the most commonly underestimated. One week of 5-hour nights reduces testosterone by 10–15% in young healthy men. Resistance training with compound movements stimulates testosterone release acutely and improves baseline over months. Dietary fat above 0.7g per kg bodyweight provides the cholesterol substrate for steroid hormone synthesis. Body fat reduction below 20% removes the aromatase activity that converts testosterone to estrogen in adipose tissue.
What Does HOMA-IR Tell You and What Is a Healthy Score for Active People?
HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) is calculated from fasting glucose and fasting insulin: HOMA-IR = (fasting insulin in mIU/L × fasting glucose in mmol/L) / 22.5. It quantifies how much insulin your body needs to maintain normal blood glucose. A score below 1.0 is optimal. Between 1.0 and 2.5 is acceptable with some insulin resistance present. Above 2.5 indicates clinically significant insulin resistance.
For fat loss, HOMA-IR above 2.5 means fat cells cannot mobilise their contents efficiently even in a calorie deficit. The body prefers to burn glucose while fat remains locked in adipose tissue. This is why some people lose weight in the first few weeks of a diet and then stall completely: the calorie deficit is real but the hormonal environment prevents fat mobilisation. The fix is insulin sensitivity interventions: resistance training, Zone 2 cardio, sleep, low-GI nutrition, and body weight reduction, which in turn reduces insulin resistance. Use the Bloodwork Analyzer to input your fasting glucose and insulin and get your HOMA-IR calculated alongside a coaching interpretation.
Get a Coaching Interpretation of Your Bloodwork
The Bloodwork Analyzer takes your lab results and gives you a performance-focused interpretation of what each marker means for your training, fat loss, and recovery. Not disease ranges. Performance ranges.
Open Bloodwork Analyzer →Frequently Asked Questions
What blood tests should I get for fitness and fat loss?
CBC, ferritin, fasting glucose, fasting insulin, HbA1c, TSH, free T3, 25-OH vitamin D, testosterone (men), and lipid panel. Approximately Rs 2,000–3,500 at major Indian diagnostic labs. Get it once before starting a programme and every 6 months thereafter.
What is a good ferritin level for athletes?
Performance optimal is 50–100 ng/mL. Below 30 ng/mL in women and 40 ng/mL in men produces measurable fatigue and reduced VO2max even without clinical anaemia. Standard lab normal ranges (above 12–15 ng/mL) are not calibrated for athletic performance.
What TSH level is optimal for fitness and fat loss?
TSH above 2.5 mIU/L is associated with reduced TDEE, slower recovery, and impaired fat loss even within the standard normal range. Free T3 in the upper third of the reference range is the functional target. Prolonged dieting suppresses T3 conversion and can push TSH upward.
What testosterone level is considered low for men who train?
Below 400 ng/dL produces meaningful impacts on muscle protein synthesis and recovery for active men. Performance optimal is 500–900 ng/dL total. Always check free testosterone alongside total because high SHBG can make total testosterone look normal while free testosterone is low.
How do I improve my bloodwork markers through training and nutrition?
Ferritin: increase haem iron intake and address depletion causes. HOMA-IR: resistance training, Zone 2 cardio, low-GI diet, sleep. TSH: address calorie restriction severity, increase selenium and iodine. Testosterone: sleep, compound resistance training, dietary fat above 0.7g per kg, reduce body fat. Vitamin D: supplementation with monitored sun exposure.