A calorie surplus occurs when more calories are taken in than the body expends and it often leads to obesity. The mechanisms underlying fertility impairment induced by obesity are complex. Endocrine disorders, genetic components and physical or chemical factors are all involved in the development of subfertility caused by excess food energy intake.
Pre-conception weight is one of the major risk factors for fertility outcomes and it is well accepted that weight loss improves fertility in overweight and obese women. Women with a body mass index (BMI) >30 kg/m2 are classed as being clinically obese and have natural menstrual cycle disruptions at a rate of almost three times higher than women of a healthy weight. A positive relationship also exists between pre-conception body mass index and the time needed to fall pregnant in women who are overweight and obese.
Carrying excess weight prior to conception can be an obstacle for obese women in getting pregnant, resulting in many women looking to healthcare professionals for assistance. Many overweight women who struggle with fertility have co-morbidities such as polycystic ovarian syndrome (PCOS) which poses additional challenges to fertility in itself due to disturbances in insulin resistance, sex-steroid metabolism and menstrual cycles.
PCOS is a health problem that can affect a woman’s menstrual cycle, fertility, hormones, insulin production, weight, heart, blood vessels, and appearance. The condition is now one of the most common endocrine problems seen in women of child-bearing age, affecting 6-10% of women in this group. It has been estimated that 75% of infertile overweight or obese women have PCOS.
Women with PCOS typically have problems falling pregnant or are infertile, and this is by far the most common reason women are referred to fertility specialists. Increased levels of testosterone are also found, causing acne, excess body and facial hair and sometimes accelerated loss of scalp hair. Self-esteem and body image are often affected because of all these problems. Furthermore, issues of femininity and sexuality can contribute to depression, social isolation, decreased quality of life and other mood changes.
Autophagy helps to explain why excess calories are associated with many diseases and premature death, whereas restricting calories while maintaining adequate nutrition is associated with preventing disease and prolonging lives.
Autophagy also activates apoptosis (programmed cell death), which could lead to oligozoospermia (low concentration of sperm in semen) and infertility. Autophagy also regulates inflammation, which is closely associated with impairment in male sperm maturation process (spermatogenesis). Autophagy was also indicated to be involved in the regulation of sperm survival and motility.