Body & Exercise · 6 min
Metabolic health and male fertility
Top things to know
South Asian men have 2 to 4 times higher rates of type 2 diabetes, and it affects sperm too.
High insulin lowers SHBG, which reduces effective testosterone and sperm production.
Vitamin D deficiency is very common in South Asian men and is linked to lower sperm count and motility.
Erection difficulties can be an early sign of heart trouble, sometimes years before; it deserves a proper check.
Why does metabolic health matter especially for South Asian men?
South Asian men develop metabolic syndrome at younger ages and lower thresholds than White European men. , diabetes, high blood pressure, and abnormal cholesterol affect your hormones, your sperm, and your fertility, not just your heart.
Myth
BMI doesn't affect sperm quality, body weight is separate from fertility
Evidence
Obesity and insulin resistance lower Sex Hormone Binding Globulin (SHBG), which reduces effective testosterone and impairs sperm production. South Asian men are particularly affected because metabolic risk is higher at lower BMI thresholds in this population (Sattar & Gill, Lancet 2015).
Sattar N, Gill JMR. Type 2 diabetes in South Asians. Lancet Diabetes & Endocrinology. 2015.
Your BMI on the South Asian threshold
The standard BMI thresholds (overweight: 25, obese: 30) underestimate metabolic risk in South Asian men. The South Asian-specific thresholds are lower: overweight from 23, high risk from 27.5. This calculator shows where your numbers sit on both scales.
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South Asian men have 2 to 4 times higher rates of type 2 diabetes than White European men, and this directly affects fertility.
Sattar and Gill, Lancet Diabetes & Endocrinology, 2015
How does insulin resistance affect testosterone and sperm?
leads to higher insulin levels in the blood. High insulin reduces Sex Hormone Binding Globulin (SHBG), which in turn can lower effective levels. Low means lower sperm production.
This creates a cycle: → low → reduced fertility → often weight gain → worse . Breaking this cycle through diet, exercise, and sometimes medication can significantly improve fertility.
How does vitamin D deficiency affect male fertility?
Vitamin D deficiency is very common in UK South Asian men, with published UK cohort studies reporting rates ranging from around 55% up to 94% depending on season, ethnic subgroup, and the lab cut-off used. Higher melanin reduces vitamin D synthesis from sunlight, and UK latitude limits UV exposure October to March.
Vitamin D receptors are present in the testes. Deficiency has been associated with lower sperm count, reduced motility, and abnormal morphology. A 25-hydroxy vitamin D blood test at your doctor is the first step; your doctor can advise on whether supplementation is appropriate and at what dose.
How can you improve your diet for fertility without abandoning cultural food?
Traditional South Asian diets can be both protective and harmful for metabolic health: Protective elements: • High vegetable intake in many regional cuisines • Turmeric, ginger, anti-inflammatory properties • Lentils, beans, good protein and fibre sources Potentially harmful elements: • High refined carbohydrate intake (white rice, white flour rotis/naan) • Large portion sizes, culturally associated with hospitality • High sugar intake in chai and mithai • Ghee and oil quantities in cooking • Late-night eating patterns
This isn't about abandoning your food culture. It's about understanding which aspects support your health goals and which might be working against them. Small changes such as brown rice instead of white, less sugar in chai, and smaller portions can make a measurable difference.
Why does cardiovascular health affect male fertility?
The blood vessels that supply the reproductive organs are among the smallest in the body. Cardiovascular problems often show up as sexual and reproductive problems before they show up as heart problems.
Erectile dysfunction, for example, can be an early warning sign of cardiovascular disease, sometimes appearing 3–5 years before a cardiac event. If you're experiencing erection problems, this is worth discussing with your doctor, not just for fertility, but for your overall health.
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Frequently Asked Questions
Does diabetes affect male fertility?
Yes. Metabolic health directly affects sperm quality and testosterone. South Asian men develop type 2 diabetes at two to four times the rate of White European men, so this connection deserves more attention than it usually gets.
Why are South Asian men at higher metabolic risk?
South Asian men develop insulin resistance and type 2 diabetes earlier and at lower body weights than White European men. That pattern affects energy, testosterone and fertility, and it responds to changes in food, movement and sleep.
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Reviewed by clinicians
Authored and reviewed by clinicians from the founding team. Information only, not personalised medical advice.
From the team behind Her Holistic Health, founded by Dr Divpreet Sacha, NHS-trained GP.