Age

18–60

Sex

MALE

Healthy volunteers

Accepted

Body mass index (BMI) ≥ 30 kg/m\^2 \[Part: 1, 2\& 3\]
Evidence of reduced reproductive capacity (e.g. reduced sperm concentration \[applicable for study B\]

History of undescended testes, testicular surgery or mumps infection
Hormonal therapy such as testosterone or selective oestrogen receptor modulators
History of systemic cytotoxic therapy or pelvic radiotherapy
Chronic systemic disease, such as cardiac, renal or liver failure
At least one of the following:
Alcohol intake \>30 units per week Smoking daily Recreational drug use at a frequency not less than weekly
Acute illness likely to affect the result of study
Impaired ability to provide full consent to take part in the study
An occupation requiring strenuous physical exercise that may require a high energy diet

Investigating the Physiological Effects of Weight Loss on Male Fertility