Do girls have to reach a certain weight before they begin menstruating?

When I was young, I heard somewhere that girls tended to begin menstruating when thweight periodey reached 45kg in weight. I reached 45kg in weight when I was 13 3/4 and I began menstruating at that age, so for me at least that ‘fact’ seemed to hold true.

More recently I’ve become much more skeptical about whether girls really do need to reach a certain weight before they began menstruating. R. E. Frisch first came up with this “critical weight hypothesis“. He proposed that girls needed to reach a certain weight (around 47kg) before their bodies could begin to menstruate. It is an interesting theory, but research has proven that the “critical weight hypothesis” is wrong. Girls can begin menstruating at any weight, as long as they have enough fat on their bodies.

Although the critical weight hypothesis is wrong, researchers have continued to investigate the link between weight & height and menarche. These studies have found that height is a more important indicator of menarche than weight. According to one study in Taiwan, there is no change in weight velocity at the age of menarche, but there is with height: “height velocity reaches a peak 1 year before menarche but height velocity stopped increasing within 1 year after menarche.”

This is interesting. I just had a look at my gr
owth chart & it seems to be consistent with the findings of this Taiwanese study. My growth rate really slowed down after menarche: it went from 6cm/year in the two years before menarche to 2cm/year in the two years post menarche.  My weight, however, didn’t seem to be connected to my menarche age at all.

Other physical indicators of menarche:

“Menarche usually occurs about two years after your breasts develop (thelarche) and between 4 and 6 months after the growth of your pubic and underarm hair.” I can’t remember when my pubic/underarm hair began to grow,
but that is interesting! I do remember that my breasts began developing when I was eleven, a couple of years before I got my first period.

My hips began to widen at almost the exact same time as I began menstruating. I wonder whether hip growth is a sign that menarche is coming (or can hips widen at any time)?

Psychosocial effects of early puberty:

Girls who go through puberty early tend to get lower marks at school & have lower self-esteem than their peers (perhaps because girls who develop early are quickly sexualised and more likely to be shamed ‘sluts’). In contrast, boys who are early developers do well at school & have higher self-esteem than their peers (perhaps because they are looked up to by their peers and can ‘get’ the girls more easily). Both girls and boys who develop early are exposed to more risks than late-developers (eg. early se
xual activity, alcohol & drugs).

Psychosocial and physical effects of early menarche:

At age 15-16, girls with menarche before age 11 (early) were more norm-breaking, including being delinquents. In addition, they had earlier advanced sexual experiences. Early-developed women had lower academic education. At age 43, women with early menarche were shorter and heavier, had worse physical fitness and dieted more frequently compared to other women. There was no difference in quality of life.

Early menarche is related to adult height: Research has shown that girls who go through menarche early tend to be shorter than girls who go
through menarche later: “The daughters of short women matured early and continu
ed growing heavier, but they stopped growing taller and were overtaken in height by the later-maturing daughters of tall women.” Another study found the same results: ““Our results support the general belief that women who reach their menarche at a later age will eventually grow taller compared with women who reach their menarche at an earlier age. A delay in menarche allows more growth of the long bones before the epiphyses unite and results in a taller adult height… for each year of delay in when a woman reaches menarche, she will grow approximately 0.35 cm taller in total body height.”age period

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17 Responses to Do girls have to reach a certain weight before they begin menstruating?

  1. Jo says:

    Ok I know this has nothing to so with it but I need help ok I am growing breasts and I’m getting mucus on my pants but no blood none at all my mum says its just not time but I know it is every thing else is happening but that do you have any advice any ideas of what I can do or any explanations.

    • Ally B. says:

      Hey Jo,
      It’s called discharge. It means your period is coming in 6-18 months. Mine came after 2 years (24 months) though, so it depends on the girl!
      Wear a pantiliner so you don’t stain you undies. Also go out and pick out some pads and make a period kit so you have what you need when you start.
      Hope I helped,

  2. cathy says:

    In response:
    1. I was roughly 10 when my breasts began to develop, and about the same time started to grow, but only started mensturating when I was about 4 years older.
    2. I recall a friend at school whose weight fluctuated around the 45kg mark. When she took her suppliments to aid weight gain, she would have a regular period, if she didn’t take the suppliments, and let her weight drop, her periods would stop.

    • atozinco says:

      Hi Cathy – I was 11 when my breasts began to develop, and 13 when I got my period. Although there is no set body weight that girl’s have to reach to start their periods, girls do have to have a sufficient proportion of body fat before they can begin menstruating – this must have been what your friend experienced – when her body weight dropped to around 45kg (or less) her body fat levels became inadequate for menstruation.

  3. kkim77 says:

    This ncbi stated different result, make me wonder which one is true.

    Myth: menarche means the end of growth is near

    The reality is that the average gain in height after menarche is about 7 cm (3 inches), and it is even greater for girls who menstruate on the early side of normal. Follow-up data from the Fels Longitudinal Study show that girls who start menstruating at age 10 grow, on average, 10 cm (4 inches), while those in whom menarche is delayed until age 15 grow, on average, 5 cm (2 inches).7 Additional reassurance is provided by data suggesting that earlier thelarche is associated with a increased interval before menarche: for example, an 8- or 9-year-old girl who has just started developing breasts will have an average time to menarche that is closer to 3 years than 2.8 The combination of a longer time before menarche and greater height gain after the start of menstruation may explain why girls who start puberty at about 6 to 8 years old do not end up short as adults. Conversely, the lesser gain in height after menarche and shorter interval between thelarche and menarche in girls with pubertal delay may explain why the pharmacologic delay of puberty (using depot gonadotropin-releasing hormone agonist preparations) has inconsistent and limited effects on increasing their final height.9

    • atozinco says:

      Hi kkim77, thanks for your comment. It makes sense that girls who are 10 years old have a lot more growing to do than girls that are 15 years old (regardless of when they started menstruation). However, most research that I have seen indicates that girls who start menarche at a younger age will generally become shorter adults (when compared to girls who start menarche at an older age). For example: Age at Menarche in Relation to Adult Height: The EPIC Study 2005: ( “Our results support the general belief that women who reach their menarche at a later age will eventually grow taller compared with women who reach their menarche at an earlier age… for each year of delay in when a woman reaches menarche, she will grow approximately 0.35 cm taller in total body height.”

    • Mary says:

      It is all interesting and fascinating, but how do you explain this difference. Me and my sister came from the same mother and father, we both had the exactly same diet, same health care and we both entered the puberty at the same age. For some reason she grew 2 inches taller but besides being taller than me, her own builth is rather fragile while mine is rather muscular. I think there is another factor in the story too. It is not only important at what age, but what is an amount of the hormones that a body is going to release in a certain time span. I grew up to my present height in only 5 months and my sister grew for years. She is only 2 inches taller and heavily underweight. She is 5 foot 6 and I think she has under 105lbs.

  4. melanie house says:

    i have been asking that forever thank u for telling me that. i am 140 lb and i thought u had to be that weight but i still haven’t had my period

  5. Ally B. says:

    81lbs going strong
    Got mine a month ago
    Haha science wizards

  6. Ally B. says:

    By the way I am 12, in 7th grade

  7. mb says:

    how tall at 81 lbs?

  8. Holly says:

    hey, i am 13 and i havent had my menarche yet. i have develop breasts,armpit and pubic hair. i am told that girls can grow tall faster if they have their period started. but i havent had mine and i have grow about 5 to 6cm in the past one year. my friend told me that i will not grow any taller anymore if i have my it true?

  9. Brooklyn says:

    Hey! I thought I had my period around Christmas 2013, but it never came back. So I really don’t know if I had it or not. I’m 14 and I’m 90lbs (I’m not anorexic just built small) and I’m not sure whether or not I have enough body fat to have my period, everything that your describing has happend to me just not the actual period haha. Just wondering how much body fat I need and how I can get there? What is the average weight that girls have there period at?

  10. Vanessa Cat says:

    Hi,can i get my period without ever having discharge?

  11. Vanessa Cat says:

    can i get my first peroid without ever having discharge?

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