If done appropriately, intermittent fasting can work to help you achieve your goals, but if done wrong, it could be counterproductive. We suggest a Paleo Eating Pattern℠ or PEP℠ that we sometimes use that keeps the fasting parameters on the conservative side (check out our blog on Paleo Eating Pattern℠). While some women who try intermittent fasting say it’s the best thing that’s happened to them since low fat yogurt, others report serious problems, including binge eating, metabolic disruption, lost menstrual periods, and early-onset menopause. This has happened in women as young as their mid-20s. Intermittent fasting can be totally different for women than for men.
Not Fair! Why are women’s hormones affected more than men’s?
It may seem unfair that men get to walk around looking ripped, and women are struggling to get lean? Low-energy diets can reduce fertility in women. Being too lean is a reproductive disadvantage and female physiology is exquisitely tuned to any threats that affects fertility; and a decreased food supply is a big one. This makes good evolutionary sense as human females are totally unique in the mammalian world. Nearly all other mammals can terminate or pause a pregnancy whenever needed. Female humans can’t. In humans, the placenta breaches the maternal blood vessels, and the fetus is in complete control. The baby can block the action of insulin in order to hoard more glucose for itself. The fetus can even make the mother’s blood vessels dilate, adjusting the blood pressure to get more nutrients. The fetus is determined to survive no matter what the cost to the mother. This phenomenon, which scientists actually compare to the host-virus relationship, is what’s known as “maternal-fetal conflict.” Once a woman becomes pregnant, nothing the mother does can cause the fetus to stop growing. The result: Fertility at the wrong time, such as during a famine, could be fatal to both of them. This is why the reproductive pathway in women is sensitive to metabolic energy cues at multiple levels.
How does the body “know”?
A women’s hormonal balance is particularly sensitive to how much, how often, and what she eats. If there isn’t much to eat, you’ll lose weight and as much as 25% of the lost weight is muscle. That is why our Soma Science℠ approach requires appropriate strength training to preserve lean muscle during weight loss. But the situation is actually more complicated than that. Even women who aren’t especially lean can also stop ovulating and lose their periods with food scarcity. That’s why scientists have come to suspect that overall energy balance may be more important to the hormonal process than body fat percentage.
Stresses and energy balance
Severe negative energy balance in women may be to blame for the hormonal domino effect that occurs. And it’s not just about how much food you eat. A negative energy balance (taking in less fuel than you actually need causing your body to dip into stored energy; fat and muscle) in your body can result from:
- too little food
- poor nutrition
- too much exercise
- too much stress
- illness, infection, chronic inflammation
- too little rest and recovery
Even the stress of trying to keep warm can use up energy reserves.
Any combination of these stresses could be enough to put you into severe negative energy balance and stop ovulation. Examples include, training for a marathon and nursing a flu; too many days in a row at the gym and not enough protein and vegetables; intermittent fasting and being stressed out over paying your bills. Psychological stress can absolutely play a role in damaging our hormonal equilibrium. Our bodies can’t tell the difference between a real threat and something imaginary generated by our thoughts and feelings. The stress hormone cortisol inhibits the hormone GnRH and suppresses the ovaries’ production of estrogen and progesterone. Meanwhile, progesterone is converted to cortisol during stress, so more cortisol means less progesterone. This leads to estrogen dominance in the body. You could be hovering at an “obese” 30 percent body fat, but if your energy balance is negative for a long enough time, especially if you’re stressed, reproduction stops. That’s the concern for women.
Estrogens and other hormones
In general, women tend to eat less protein than men. Fasting women will consume even less protein. Consuming less protein means taking in fewer amino acids. Amino acids are needed to activate estrogen receptors and synthesize insulin-like growth factor (IGF-1) in the liver. IGF-1 triggers the uterine wall lining to thicken and the progression of the reproductive cycle. So low protein-diets can reduce fertility. It’s important to note that estrogen isn’t just for reproduction. We have estrogen receptors throughout our bodies, including in our brains, GI tract, and bones. Change estrogen balance and you change metabolic function all over: cognition, moods, digestion, recovery, protein turnover, bone formation, etc.
When it comes to appetite and energy balance, estrogen works in a few ways. First, in the brainstem, estrogens modify the peptides that signal you to feel full (cholecystokinin) or hungry (gherelin). In the hypothalamus, estrogens also stimulate neurons that halt production of appetite-regulating peptides. Do something that causes your estrogen to drop, and you could find yourself feeling a lot hungrier and eating a lot more than you would under normal circumstances. Estrogens are key metabolic regulators.
Estrogens in plural. This is because the ratios of the estrogenic metabolites (estriol, estradiol, and estrone) change over time. Before menopause, estradiol is the big player. After menopause, it drops, while estrone stays about the same. The exact roles of each of these estrogens remain unclear. Some theorize that a drop in estradiol may trigger an increase in fat storage. Because fat is used to make estradiol. This may partly explain why some women find it harder to lose fat after menopause. And it might serve as a reason to care about your reproductive health even if you’re not focused on making babies.
Pregnant women have obvious extra energy needs. So if you’re starting a family or pregnant, fasting is not a good idea. Similarly, if you’re under chronic stress or if you aren’t sleeping well, a fast would just add more stress. Your body needs nurturing, not additional stress. If you’re struggling or have struggled with disordered eating, you probably recognize that a PEP℠ protocol could lead you down a path that might create further problems for you. Don’t risk your health if you fall into one of these categories. You can achieve similar benefits in other ways. If you’re new to diet and exercise, PEP℠ might look like a great approach for weight loss. Address any nutritional deficiencies before you start experimenting with PEP℠. Ensure you’re starting from a solid nutritional foundation first.
What to do now
Based on what we know, intermittent fasting probably affects reproductive health if the body perceives this as a significant stressor. Therefore, anything that affects your reproductive health, affects your overall health and fitness. Intermittent fasting protocols vary, with some being much more extreme than others. Our PEP℠ approach is on the conservative end. Factors such as your age, your nutritional status, the length of time you fast, and other stresses in your life, including exercise, are also likely relevant.
What to do if fasting isn’t for you and on the other days?
How can you get in shape and lose weight if PEP℠ isn’t a good option for you? Learn the essentials of good nutrition. It’s by far the best thing you can do for your health and fitness.
- Cook and eat whole foods.
- Exercise regularly.
- Stay consistent.
- Work with us as your guide.
A PEP℠ approach may be a good option to help you learn to work through your hunger. Listen closely to your body, avoid fads or extremes, and follow good advice.