According to the report “Healthy Parents and Children 21 Promotion Council: Eating Habit Guidelines for Pregnant Women, published by the Ministry of Health, Labour and Welfare, women whose body types are classified as “underweight” before becoming pregnant and women who do not properly gain weight during pregnancy are at higher risk for giving birth to low birth weight babies.
Also, according to demographic statistics, the percentage of low birth weight newborns is on an upward trend, growing from 5.1% (1975) to 9.6% (2009) of total newborns. Additionally, the average birth weight is on a downward trend, dropping from 3,200g in 1980 to 3,000g in 2010. Reports point to the possibility of underweight body types before pregnancy and the attempts of many pregnant mothers to suppress weight gain during pregnancy as some possible reasons behind these trends. There are also survey results which show that low birth weight babies are at higher risk of diabetes mellitus, hypertension, and other lifestyle diseases after becoming adults.
Furthermore, sudden loss of weight due to dieting can reduce overall body fat percentage. Body weight percentage and ovarian function are intimately related, and a reduction in body fat percentage can suppress the function of the pituitary gland in the brain, leading to menstrual irregularities, amenorrhea, and other ovarian dysfunction. As the restoration of ovarian function can be quite difficult after cases of severe amenorrhea, it is essential that women exercise caution when considering extreme diets.