A few months ago I did a few posts about the menstrual cycle and how it might impact on our strength, endurance and diet. In particular I was trying to get to the bottom of how I might flex my diet and training to work with my hormone cycles rather than against them. After I’d finished the post I realised that I’d forgotten one crucial point – I use a hormone based contraceptive pill. It was time to look at how the hormone balance changes when on the contraceptive pill to see if a different diet and training cycle is needed to get the best out of those altered hormone cycles.
Revision of the menstrual cycle
Before I get started, here’s some quick revision of the menstrual cycle. A standard cycle, lasting approximately 28 days, is divided into two parts. During the first half, the follicular phase which starts on the first day that menses occurs, progesterone levels remain very low and level while oestrogen gradually rises. Oestrogen reaches a peak near the end of the follicular phase, triggering a spike in the follicle stimulating hormone (FSH) and the lutenizing hormone (LH). 24-36 hours after the surge in LH the dominant follicle will release an egg.
The second half, known as the luteal phase, is when the egg passes along the fallopian tube towards the womb, hoping for fertilisation. At the same time, with oestrogen levels low, the body experiences a surge in progesterone. If the egg is fertilised then progesterone levels remain elevated, creating the perfect hormonal soup for pregnancy, however if the egg isn’t fertilised then progesterone levels drop off again signalling the body to shed the womb lining and have another go.
How does the contraceptive pill work?
The contraceptive pill essentially works by tricking the body into believing it is already pregnant. If the body thinks it is pregnant then it won’t ovulate and there is no release of an egg. After all, if you were already pregnant and then another egg was released and got fertilised a couple of months later it could get a bit messy…
Thinking about that on a hormone basis, what we need to do is get the hormone balance to a state where there is no trigger for that spike in FSH and LH. Progesterone decreases the release of FSH and LH (though not directly – more can be learned from Wikipedia) and for this reason it is possible to create a progesterone-only pill, increasing levels of progesterone at times when it would usually be low. It has also been found that, by another mechanism, additional oestrogen can also decrease the release of FSH and inhibit follicular development. The combination pill contains both oestrogen and progesterone. As an aside, it’s worth noting the fact that progesterone also reduces the cervical mucus while also making it more viscous (which makes it harder for the sperm to penetrate the cervix).
These changes to our hormone patterns aren’t just relevant to those on the contraceptive pill. It’s the same principle used by any of the hormone-based contraceptives.
An amended view of the hormone cycle
I’ve been trying hard to find a graph of how this additional input of hormones changes the hormone balance and the best I could find was the following:
In this graph the LH is green, FSH is yellow, oestrogen is blue and progesterone is red. The top half shows a normal cycle and the bottom half shows the cycle when on a progesterone-only contraceptive pill. This suggests that oestrogen is entirely suppressed while progesterone is high at all times. Clearly with a combination pill (containing both hormones) there would be some oestrogen, but the crucial element is there – one of keeping the ratio skewed towards progesterone so that the LH and FSH are suppressed.
With the combination pill there is a seven day period when you don’t take the pills and the body adjusts to withdrawal from the additional hormones. This causes break-through bleeding (an apparent menstrual flow but not a true period since there was no ovulation first) and a drop-off in progesterone levels for a brief time. However, I haven’t been able to find an accurate graph to know exactly what happens in this “off” week. Goodness knows what is actually happening – is this withdrawal a really bad thing for us or is it a good thing for the body to have a week’s break from the hormones?
Presumably, if you are using some other hormone-based contraceptive, such as a hormone IUD or patch, you would not see this withdrawal week as the hormones are constant every week with no “off” week when you stop dosing with the artificial hormones.
How might this affect our view of diet and training?
This emphasis towards progesterone is very different to the normal hormone cycle and, as you may recall from my previous set of posts on the menstrual cycle, different hormone balances affect how our body responds to the different macronutrients and to different training stimuli. The question is how to best leverage that knowledge to work with our bodies.
However, I’ve written so much now that I think it is probably time to stop for this week. Next week I’m going to write about how I see hormone-based contraceptives impacting on our diet and training and also take a look at the information given to me by some of my readers about their cycles to see if my theories are substantiated by what is really happening to other women.
Interesting topic that one never sees addressed! I look forward to reading more.
In the past year I have recently swapped to a progesterone only pill and I have noticed a HUGE change in my menstrual cycle.
Not only does it last twice as long, but it is very heavy (for me). I’ve always had very light periods; so light in fact I’m able to use panty liners the majority of my period to maintain hygiene. Now, I’m estimating it is about 3-4x heavier and going for twice as long as it used to be on the combined pill or without contraception at all. I do think that it is affecting my energy levels too, which is frustrating as in the past my period has never affected me.
That’s fascinating. I’ve heard stories about progesterone-only pills but you’re only the second person I’ve come across who uses/used them. The other woman found another solution eventually (I think she went with a copper IUD). There was some reason why she had to be careful with intakes of additional oestrogen which prevented her using the combination pill or other hormone contraception. Do you think you’ll stick with progesterone-only given the side effects?
Thanks Ruby. I’ve been fascinated with it all for a while and frustrated by the lack of material about it. After all, our menstrual cycle and the widespread use of hormone contraceptices are things that we can’t exactly ignore.
Well, I don’t have a choice when it comes to the pill. I have high blood pressure, so the combined pill is contraindicated for me. I’ll just have to deal with it. My doctor isn’t concerned because the flow is still normal…. which is true, my cycle has always been very light in the past and now it’s probably closer to what most women experience monthly.
Training and diet on the contraceptive pill // Jun 23, 2011 at 21:01
[…] Last week I spent some time writing about what the contraceptive pill and other hormone-based contraceptives do to our hormone cycles, when compared to the natural cycle that our bodies would follow without contraceptives. […]
Real experiences compared to hypotheses about the menstrual cycle // Jun 30, 2011 at 21:04
[…] through some technical material on what is going on with the female sex hormones when taking hormone-based contraceptives. Last week I put some consideration into what training and diet might work well with […]