**2.4 Obesity**

Overweight and obesity cause excessive accumulation of fat in the body, which is determined by using the body mass index. Men who are overweight and obese are more likely to have low sperm quality and infertility. A systematic review of 30 studies involving 158,115 men found that paternal obesity was associated with reduced male fertility. Obese men have a higher percentage of sperm with fragmented DNA, mitochondria with low membrane potential, abnormal morphology, and infertility [14].
