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Ideal body fat for conception

(23 Posts)
radiatormesh Thu 30-Jan-14 18:05:33

I have just weighed myself and am quite shocked at how skinny I've got.

I currently have a BMI of 19 and body fat of around 18% (according to my scales, which I appreciate aren't going to be totally accurate).

I was heavier when I fell pregnant with #1 (BMI of around 22) and about half a stone heavier with #2 (BMI of around 20). No idea what my body fat was.

I work out 6 times a week (I work in fitness) and walk everywhere, so I burn a lot of calories every day, and whilst I don't deprive myself, I probably do fill up on fruit and veg etc rather than heavier stuff. I'm full of energy though and don't feel like my body's struggling in any way: I feel great to be honest.

I seem to remember a statistic that body fat should be around 22% for optimal conception: does anyone have a link to this or know anything more?

I know that the acid test is said to be whether or not I'm ovulating. I think I am (I've just cut down on BF #2 and things are starting to get back in gear so I'm not really in a regular cycle yet) but I think my lining is very thin (very light periods), and I'm now starting to think this could be linked to my activity/weight rather than just the BF...

Anyone have any proper scientific knowledge or advice?? I do quite like my figure and love working out/being active, so whilst I'm happy to put on weight if it'll get me a baby, I'd rather not if I don't have to...


Aquarius1 Thu 30-Jan-14 18:15:27

I've been wondering the same thing - ttc 2 yrs and no joy as yet - at the FC I was told to put on weight and that they like your BMI to be at least 20 . I've got it up from 18.5 to 19.5 but body fat is at 18%. I work out once or twice a week and don't feel i'm too skinny. I'm not sure how accurate body fat scales are - is that what you used to measure yourself?

Baxter2014 Thu 30-Jan-14 18:24:11

Like you said radiator the key is if you are ovulating or not. If you get too thin it could cause hypothalamic dysfunction which would mess with your FSH/LH levels and effect menstruation. If this is working ok I don't think you need worry.

As you know working in fitness, BMI is a very crude way of measuring a healthy weight (BMI 20-25 being 'normal') however this completely depends on your build - really muscly rugby players will have a BMI saying they are obese which is ridiculous. If you feel your weight is right for you and you are healthy that's the main thing. Only when your body fat falls to a very low percentage will it start to have an effect on menstruation. As for optimal values...who knows!!

Good luck smile

radiatormesh Thu 30-Jan-14 18:25:15

Sorry to hear of your troubles.

Yes - I used a set of scales.. I don't feel skinny either: I feel neat and trim, but not skinny. I have defined arms and legs and a nice flat tummy but I definitely don't look like I don't eat!!

naty1 Thu 30-Jan-14 19:20:15

How old is baby?
When did periods restart?
Could you be hyperthyroid?
I would aim for over 20.
Do you think Dr would measure your prolactin levels?

radiatormesh Thu 30-Jan-14 22:24:44

Baby is 11m.

Have had very very light periods (but I believe ovulatory cycles) since he was 6m.

Funny you mention hyperthyroid, since I've just been diagnosed with thyroid eye disease... My GP doesn't think I have a thyroid problem but she only ran the one test. I think though that anyone with my lifestyle would be this size: not sure it's related but it might be...

What would prolactin levels show? I still BF once a day: would that mess with the results?

naty1 Thu 30-Jan-14 22:40:34

I suppose it may show unusually high(because bf)
I would probably find out the actual readings for thyroid as whats normal may not be optimal for pg, also pg can mess with thyroid i think usually hyper then hypo but often clears within the year, but not always.
I think i was hyper after baby(lost all baby weight in 2 weeks , greedy baby) but am now hypo.
Is the 1 feed at night ?

radiatormesh Thu 30-Jan-14 22:47:53


I'm seeing my GP again tomorrow (the report from my eye specialist should have come through): is it the antibodies I need checking?

The feed is in the evening, yes. He was on two a day until a few days ago and he seems to have stopped asking for the morning one sad

What can be done if it is my thyroid?

naty1 Thu 30-Jan-14 23:10:45

Not sure i have hypo so take levoxythyroxine.
They may wait and see if it corrects after the year ie when baby is 1
They tested my tsh
Thyroid stimulating hormone.
But what i have would in theory make you overweight so i guess you would have opposite hyperthyoidism, or could kust be sorting self out after baby and bfp

radiatormesh Fri 31-Jan-14 21:02:54

Well I've just seen my GP and she ran all the blood tests, including thyroid antibodies back in November and everything is totally normal. She can't find a thing wrong with me.

So my thyroid isn't affecting my weight, meaning it's my lifestyle, as I suspected.

So does anyone have any information on this? All I can find is 'BMI between 18.5 and 25' - is there any info on body fat levels and/or the best BMI (not just what's acceptable)??

naty1 Fri 31-Jan-14 21:49:28

Thats great.
It would be interesting what the tsh level was, if it was on the lower normal.
Luckily i was tested a couple of years ago so i have a reference it was 2.1 and when up to 3.7 after the baby.
I know for hypo there is disagreements over the levels ie some think under 2 for ttc but on the labs i think it said 4 or 5 as the upper limit.
It may still be worth looking at hyperthyroidism to see if you have any other symptoms ie feeling anxious, palpitations diarrhoea etc as you gave 2 of them light periods and eyes.
No idea unfortunately about the body fat but good luck

Writerwannabe83 Fri 31-Jan-14 22:35:25

My BM was 19.6 when I conceived - no idea what my body fat percentage was though.

radiatormesh Sat 01-Feb-14 01:29:21


I've found this calculator:

Suggests that for every kg of fat-free mass you have, you need 45kcal/day of available energy (energy available post-exercise calories) to have a healthy menstrual cycle.

So I need 2004kcal plus whatever I exercise. That is a lot of food...

Demi123 Sat 01-Feb-14 01:34:55

Hi guys slightly off the topic but Have I done enough in ttc?
I have been ttc for years, I have now tested with the clearblue smiley face opk's I got my first smiley face 29th and second 30th I had intercourse 28th 30th and 31st my question is have I done enough although I didn't have intercourse the day of the first smiley even though I did it the night before?

OwlinaTree Sat 01-Feb-14 10:04:35

Think I had this problem. Came off pill and no periods. Was around 8 1/2 stone and exercising 4/5 days a week, eating v low calorie diet (doing weight watchers). Blood showed no problems, but not enough hormones to make me ovulate.

After 18 months and 6 rounds of clomid I started to do less exercise and went up to 9 stone and periods restarted.

Who knows if it just took that long for my body to recover from the pill or whether it was the weight and exercise? Maybe try cutting back your exercise and upping your calories a bit to see if it makes any difference.

eurochick Sat 01-Feb-14 10:11:41

I read a study ages ago that suggested that the ideal BMI for conception is 22. I can't remember how broad/well set up a study it was at this point though.

Aquarius1 Sat 01-Feb-14 10:33:07

One of the qualifying criteria for IVF in my area is BMI of 20 or more (can't remember what upper limit is).

Aquarius1 Sat 01-Feb-14 10:36:00

demi I'm not convinced opk's are that reliable - and it's not an exact science as to how soon you ovulate after a positive opk- so I'd keep going for a bit to be in with the best chance.

YippeeKiYayMakkaPakka Sat 01-Feb-14 10:38:01

I had similar BMI and body fat % to you when I conceived DD1 OP. I know that one anecdote doesn't = scientific proof, but just because there's an "ideal", doesn't mean your chances outside of that ideal are zero. Maybe slightly lower, but if you're otherwise healthy and have no other fertility problems, it might not be an issue.

radiatormesh Sat 01-Feb-14 12:58:30

Thanks for the advice/support.

euro - my friend mentioned that to me too, but I also can't find it anywhere!

Aquarius - that's interesting. I'd have to gain weight to be eligible. They clearly see that as the optimum range.

Yippee and Owlina - it's interesting to hear different experiences. I'm confused right now as to whether it's my weight/exercise or just stopping BF which is slowing things up. With #1 I stopped cold turkey at 12m and went into a few months of intense medical treatment which included hormones, so I have no idea how my body would have returned to fertility. So this is all new to me!!

Things are definitely happening, but reducing my workouts to 3/4xwk rather than 5/6 and increasing my calories can only help I think. I love to exercise and be strong, so I'll see how I feel doing this, but the end goal of completing our family will help smile

lottieandmia Sat 01-Feb-14 13:00:49

It probably depends on the individual. I got pregnant after a period of ill health when my BMI was only 18 and it was a one time opportunity to get pregnant.

Demi123 Sat 01-Feb-14 15:06:47

Thank you Aquarius , I have done something today also so I shall take ur advice and continue to keep trying is there a time period from when I got the smiley to wen It is ok to stop trying tho?

busyDays Sat 01-Feb-14 15:23:11

Sorry, no scientific help here, but having a low BMI hasn't been a problem for me. I have just worked it out at 16.5, making me underweight. I have no idea what my body fat. I don't do any exercise so I don't have much muscle. I have been the same weight for years, during which time I have conceived two children easily. So I don't think the BMI in itself is a problem, but can't comment much about the body fat issue.

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