Leptin and Fertility
Claire Aslangul - Thursday, August 08, 2013
Currently in Australia infertility effects 1 in 6 couples trying to conceive and unfortunately this number is increasing. The common scapegoats for this trend are older mothers and the rise in levels of obesity among both potential mothers and fathers. But this is really just a way of over simplifying something that is quite a complex problem and stating a causal link where there is only a casual link. If obesity caused infertility, then obese people would not conceive babies. If being over 40 caused infertility, no women over 40 would conceive. The reality is that obesity and infertility are separate symptoms of leptin resistance and with our current lifestyle, leptin sensitivity is reduced as we age. One the flip side, there are plenty of young, normal weight people adding to this 1 in 6 statistic.
Let's have a quick look at how leptin is linked in with fertility. If you have been reading the blog and watching the YouTube videos you will know that leptin has the role of letting our brain know that we are "full" and also giving the brain an update on how much energy the body has, not just from the meal you ate, but also the percentage of fat stores in the body. Now if the brain is beginning to lose sensitivity to leptin, the messages that come though from the body to the brain are inaccurate. The brain will always register the energy stores as being lower than what they are. It is at this point, the brain prioritises how that energy is going to be spent and either stimulates functions in the organs or switches them to low or off. The brain has a simple way of setting its priorities and that is; if I stop this will I die now, soon, later or will it stop the creation of the next generation. So if your brain is hearing "we only have a tiny amount of energy" the energy will be conserved for critical functions like keeping your heart beating and your lungs breathing. A bit of energy will be spent on keeping your liver and kidneys functioning, less will be spent on digestion, even less on skeletal muscles and way down the bottom of the list are your reproductive organs. If you body is not spending energy on your fertility, you are looking at issues like low sperm count, reduced motility, poly cystic ovaries, amenorrhea and recurrent miscarriages.
Young, skinny and subfertile.
Something we have know for a very long time is that female athletes with severe training regimes tend to stop getting their periods. Now these women are often viewed as some of the healthiest people on the planet, but that is far from the truth. The combination of intense training, low body fat percentage, high stress, reduced sleep and high carbohydrate diet have a huge and sometimes irreparable impact on their health and hormonal system. It is a two-pronged attack and is also seen now in the general population. As we know, leptin is produced by our white fat cells when we eat. If your body fat percentage is low, it will tell the brain or energy stores are low. This is exactly how it is designed to work. But when calories are being restricted, we consciously ignore the messages of we need more food. This reduces leptin sensitivity, the conscious brain over rides the instincts of the body. This instantly puts our body into a stressed state by increasing cortisol. Now, add some training into the mix. The body has allocated its energy stores and again you are overriding it with increased energy being required by the heart, lungs and skeletal muscles. There is no such thing as a free lunch, the is paid for by the digestive system, the skin and the reproductive organs. Brain is not liking this at all, up comes cortisol even further.
Ok, so high cortisol is a problem, because it sends blood flow away from the internal organs (including the sex organs) and sends it to the heart, lungs and muscles. Brain is thinking that you must have to run away from one hell of a lion if you want to run while energy levels are so low. The next huge problem with the constant production of cortisol is "pregnenolone stealing". Pregnenolone is a building block for making a whole heap of hormones. This includes cortisol (fight or flight), progesterone (used for maintaining pregnancy) and DHEA (which is then made into sex hormones like testosterone and estrogen) the more pregnenolone used to make cortisol, the less is available to make the hormones required to have sex, conceive a baby and maintain a pregnancy. This whole process seen in athletes is replicated with stressful jobs, calorie restriction particularly cholesterol and saturated fats, intense early morning workouts and other aspects of modern life.
A bit more on miscarriages.
It used to be thought that humans gave birth to their babies relatively prematurely compared to other animals due to having a small pelvis which is needed for being upright. It has recently been discovered that it is in fact that a baby is born when the mothers metabolism can no longer produce enough energy to continue to grow the babies brain. Leptin is the indicator for energy stores. The more leptin resistant you are, the less chance of carrying a baby to term, not just because of the high cortisol reducing progesterone production but because the brain believes the body hasn't the energy to continue to grow the babies brain.