What can cause low semen volume when consuming only one meal a day and drinking limited water (500 ml)?

Low Semen Volume from Severe Dehydration and Caloric Restriction

Your low semen volume is almost certainly caused by severe dehydration from drinking only 500 ml of water daily, which is far below the minimum physiological requirement and directly reduces seminal fluid production.

Immediate Physiological Problem

Your fluid intake of 500 ml/day represents critical dehydration that impairs all bodily secretions, including seminal fluid:

• Normal semen volume ranges from 1.5-5 ml per ejaculate 1, 2
• Seminal fluid production requires adequate hydration to maintain the secretory function of the seminal vesicles and prostate, which contribute 65-70% and 25-30% of ejaculate volume respectively 1
• Severe fluid restriction directly reduces the volume of all glandular secretions, including those from accessory sex glands 3

Metabolic and Nutritional Impact

Your one-meal-a-day pattern combined with severe dehydration creates multiple fertility risks:

• Caloric restriction and dehydration together can suppress testosterone production and impair overall reproductive hormone function 4, 5
• Low semen volume (<1.5 ml) is associated with decreased sperm motility, viability, and morphology even when sperm counts are adequate 6, 7
• Men with metabolic stress from inadequate nutrition show increased prevalence of oligozoospermia (low sperm count) 4

Critical Distinction: Functional vs. Structural Causes

Your situation represents functional low semen volume from reversible lifestyle factors, not structural abnormalities:

• Structural causes (ejaculatory duct obstruction, retrograde ejaculation, congenital absence of vas deferens) would persist regardless of hydration status 3, 1
• Functional causes from dehydration and nutritional deficiency are immediately reversible with adequate fluid and caloric intake 1
• Partial retrograde ejaculation should be considered only if low volume persists after correcting hydration, requiring post-ejaculatory urine analysis 2

Immediate Corrective Actions

Increase water intake to minimum 2-3 liters daily (not 500 ml), using oral rehydration solutions if plain water causes discomfort:

• Adequate hydration is essential for normal seminal fluid production from the prostate and seminal vesicles 3
• Hypotonic fluids alone may not be optimal; consider adding electrolytes to improve absorption 3
• Sip fluids throughout the day rather than consuming large volumes at once 3

Increase meal frequency and ensure adequate caloric intake (25-33 kcal/kg body weight minimum):

• Severe caloric restriction impairs reproductive hormone production and can lead to hypogonadism 4, 5
• Weight loss from inadequate nutrition negatively affects testosterone, SHBG, and free testosterone levels 4
• Multiple daily meals support stable metabolic function necessary for optimal reproductive health 3

When to Seek Medical Evaluation

If low semen volume persists after 2-3 months of adequate hydration and nutrition, formal evaluation is warranted:

• Semen analysis should be performed to assess volume, sperm concentration, motility, and morphology 3
• Hormonal evaluation including FSH and testosterone is indicated for persistent oligozoospermia or low volume 3
• Post-ejaculatory urine analysis should be done if volume remains <1.5 ml despite corrected hydration to rule out partial retrograde ejaculation 2
• Transrectal ultrasound (TRUS) is indicated only if semen volume remains <1.5 ml with acidic pH (<7.0), suggesting ejaculatory duct obstruction 3

Critical Pitfalls to Avoid

• Never assume low semen volume is "normal for you" without first correcting obvious reversible factors like severe dehydration 1, 7
• Do not delay rehydration thinking gradual increase is safer; your current intake is dangerously low and requires immediate correction 3
• Avoid exogenous testosterone supplementation if considering fertility, as it suppresses spermatogenesis and can cause azoospermia 4
• Do not rely on "dry fasting" or extreme dietary restriction as these practices directly impair reproductive function 4, 5

Expected Timeline for Recovery

Semen volume should normalize within 2-3 months of adequate hydration and nutrition, as the spermatogenic cycle takes approximately 74 days:

• Immediate improvement in seminal fluid volume should occur within days to weeks of rehydration 1
• Sperm quality parameters (motility, morphology) require 2-3 months to reflect improved nutritional status 6, 7
• Persistent abnormalities beyond 3 months warrant formal fertility evaluation 3