Based on these figures a mean BMI of 12 as the lower limit for human survival emerges - a value first proposed by James et al (1988).
If your BMI is less than 18.5, it falls within the underweight range. If your BMI is 18.5 to 24.9, it falls within the Healthy Weight range. If your BMI is 25.0 to 29.9, it falls within the overweight range. If your BMI is 30.0 or higher, it falls within the obese range.
If your BMI is: under 18.5kg/m2 – you are considered underweight and possibly malnourished. 18.5 to 24.9kg/m2 – you are within a healthy weight range for young and middle-aged adults. 25.0 to 29.9kg/m2 – you are considered overweight.
BMI had J-shaped associations with overall mortality and most specific causes of death; for mental and behavioural, neurological, and external causes, lower BMI was associated with increased mortality risk.
Infrequent Periods
The greater your BMI (particularly in the obese range over 35), the more likely you are to miss your period. It is even possible to stop bleeding altogether, a condition known as secondary amenorrhea.
BMI <18.5: underweight. BMI 18.5–24.9: normal weight. BMI ≥25.0: overweight. BMI ≥30.0: obesity.
45 (kg) divided by 2.25 (height squared) = 20. This means a person with a height of 150cm and a weight of 45kg would have a BMI score of 20. According to the BMI, that person would be in the “healthy weight range”.
18 or lower: underweight. 18.5 to 24.9: normal, healthy weight. 25 to 29.9: overweight. 30 or higher: obese.
Muscle and bone weigh more than fat, so BMI measurements can overestimate body fat in athletes and people with a muscular build or a larger body frame. Conversely, BMI can underestimate body fat in older adults and anyone who has lost muscle, according to the Harvard T.H. Chan School of Public Health in Boston.
The lowest BMI recorded was 7.5 (she was only 21 inches tall and died of hypothermia), highest BMIs are around 188 [Guinness World Book of Records]. I am using BMI instead of weight because of course height factors into how much we can and do weigh. The average BMI for women is approximately 26.8 and for men, 26.
Can a low BMI affect my fertility? Yes. Having a BMI below 18.5 is classed as underweight, which can make it harder to get pregnant. Having a low BMI can also cause your periods to become irregular or stop.
This beauty ideal became de rigueur in the industry; the average runway model has a body mass index (BMI) of 16, which the World Health Organization classifies as severely thin.
Being small, or even underweight according to the numbers, doesn't mean you need to gain weight. A healthy weight isn't necessarily “seen” and not a sign that something is wrong or that a person has an eating disorder.
A weight under 100–110 pounds (50kg)
According to the CDC, the average weight of a 12-year-old female is 92 pounds (lb) , or around 42 kilograms (kg).
Even though a 13 year old who is 70 kg is considered to be overweight as they suggest you should be weighing more like 50 to 60 plus kg, you are a growing teenager (providing that you are still growing, I'm only saying this because when I was your age I stopped growing unfortunately for me).
Taking a Closer Look at BMI
Calculated from a person's height and weight, BMI breaks down into four categories: Underweight: BMI below 18.5. Normal: BMI of 18.5 to 24.9. Overweight: BMI of 25 to 29.9.
A high metabolism means a person burns more calories at rest and during activity. Therefore, there is no piling up of fats or weight gain. A very high metabolism rate can be unhealthy as the person is unable to maintain a healthy weight.
It may be that you have a fast metabolism (meaning your body burns energy from food at a fast rate than the people around you) or you're just naturally slender. For some people, underlying health conditions and certain medications and treatments can make it difficult to reach and/or maintain a healthy weight.
The menstrual cycle does not directly impact weight loss or gain, but there may be some secondary connections. On the list of premenstrual syndrome (PMS) symptoms are changes in appetite and food cravings, and that can affect weight.
Yes, they can. Being underweight or overweight due to disordered eating will impact your hormone balance and may cause irregular periods, frequent periods, or loss of periods.
Girls who are underweight or who have eating disorders may notice a delay in the start of their periods. Girls who are very athletic might not get their periods until they stop exercising or competing so vigorously. Severe stress or some illnesses also can delay menstruation.
Their law stipulates that women and men hired as models must be certified by a physician as having a body mass index (BMI) of no less than 18.5.