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Sunday, 28 April 2013

Puberty and growth for boys

A lovely conversation with a mother about her concerns that her 12 year old son was "bingeing" has led me to share this.

Puberty takes an awful lot of energy.  Boys seem to lag behind girls age wise and there is a "school photo" moment when the girls tower over their class mates.

So how many pounds does it take to grow an inch?  I remember researching this a couple of years ago to answer a question on the forum.  However, it now seems that the "diet" world has taken over the internet.  When I typed exactly the same question from 2010 into Google, I was presented with stuff that I wish I didn't now know.  Apparently if you lose 35lbs (according to Dr OZ), you can gain an inch in penis length.  Really?  Really?  Well, I think that is just darn unfair and sexist - not that I want my girly bits to grow an inch, you understand.....

I also found myself on a teenage body building site.  Never again.

I did find the "How stuff works" website, which had this to say:

Most boys, though, will take growth any way they can get it. After all, they don't want to have girls their age towering over them for the rest of their lives. Once boys start really growing, it doesn't take too terribly long to catch up with the other gender. Between the ages of 12 and 16, boys grow in height as much as a full foot (.3 meters). Weight gain in this same period can vary from 15 to 65 pounds (6.8 to 29.5 kilograms) [source: University of Virginia].

I am a little concerned about those who only gain 15 lbs during this period.  Perhaps they just don't grow so much?

I also came across a chart "Proper Height and Weight for Age".  I needed to find a definition of proper


1. Characterized by appropriateness or suitability; fitting: the proper knife for cutting bread; not a proper moment for a joke.
2. Called for by rules or conventions; correct: the proper form for a business letter.
3. Strictly following rules or conventions, especially in social behavior; seemly: a proper lady; a proper gentleman.


Yikes.  In order to be seemly, correct and fitting, I need to lose 7 3/4 inches and quite a few pounds.   Should I worry?

Praise be for the Royal College of Psychiatrists for giving us an average calorie requirements for puberty:


Oral feeding requirements
The estimated average energy requirement in the UK for healthy girls aged 11– 18 years ranges from 1845 kcal to 2110 kcal (7750–8860 kJ) per day; for boys of the same age the range is 2220 kcal to 2755 kcal (9325–11 570 kJ) per day (Department of Health, 1991). 


Boys seem to require a lot more calories for puberty - (Warning: icky picture) this is where my Dr Oz penis length thing runs into difficulties.....

My research led me to, as a general rule of thumb, 30-40 lbs for puberty and between 5-8lbs for an inch in height.  Do not expect to somehow see this on the scales overnight.  That would be too easy.

"Oh son, you gained 30lbs.  By tomorrow morning your voice will have dropped, you will be shaving and then Dr Oz says you need to lose 35lbs....."

1 comment:

  1. C, you KNOW ILU, but: The 5-8lb per inch thing is a real problem, and should be shown the door, IMO. It's derived from those same effed up actuarial weights the insurance industry developed, that give us those craptastic Ideal Body Weights. BTW, it's worth noting that the original tables & formulas were developed in the 1930s - right when food insecurity was a HUGE problem in the US and Europe.

    I would still be hesitant about the UK requirements. Daily energy needs are just about THE most variable thing EVAR, and you can multiply that by at LEAST 100 for kids. Populational "ranges" are at high probability to be off by a considerable amount. Added to this problem, is that the formulas to calculate daily caloric needs have been "tweeked" over the past decade or so, and most of the publicly available ones substantially UNDERESTIMATE caloric requirements. Even on the USDA and other "official" websites.

    (The reason for this is, of course, the Obesity Epidemic BOOGA BOOGA BOOGA, and the completely UNVALIDATED assumption that people are fat because they are eating "too much". As a result, the calculators are adjusted down.)

    However, you can still get good information if you know where to dig. Which of course, I do. Protein-calorie and micronutrient malnutrition are large risk factors for worse hospital outcomes. The assumptions the literature make for hospital ICU patients are very different from those made for all of us eating too much fat fatties on the outside.

    Here is a great pediatric monograph. The topic is (sadly) children who need tube feeding. This gives the range for a 12-18yo child as 30-60kcal / kg / day. Please note that that is a HUGE range. A 100lb kid - which would be a very small 18yo or a middlin 12yo, is about 45kg, and the range would be 1350 - 2700 for that kid.

    Now, this is baseline for a healthy kid.
    - a fever increases daily needs by 10-12% per increased degree C;
    - cardiac failure increases it by 15-25%;
    - surgery by 20-30%;
    - LONG TERM GROWTH FAILURE BY 50-100%. (caplockishness mine).

    http://www.uic.edu/classes/pmpr/pmpr652/Final/krauss/pedsnutrition.html

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