A few weeks ago, I tweeted my concern about a low carb diet for young women.
Apparently, my tweet was offensive to some people (men). They explained to me that it’s purely “anecdotal.” There is no known mechanism, they said, so it must not really be happening.
Except it is really happening. Ask anyone who works with young menstruating women. Or not menstruating, as the case may be.
True, we don’t know the exact mechanism. That’s because no researcher has yet asked the question:
What does a very low carb diet do to periods?
Until we have the answer, we can only surmise. I surmise that for some women inadequate starch signals the hypothalamus that there’s not enough food to reproduce. It may be via the hormone leptin. It may be via the microbiome. It is an adaptive starvation response, and may also be why a low carb diet can cause hair loss. [For an update and a possible mechanism of why it happens, please see my 2016 post Are You Eating Enough to Get a Period?]
In contrast, some women do well on a low-carb diet. They may even regain the periods they’d lost on a high-carb diet (see insulin-resistant PCOS discussion below).
It comes down to this: There are different individuals in the world, with different glycemic responses.
There are also different carbohydrates. For example, there is sugar and there is wheat, and they are two worst carbohydrates.
Sugar is the worst carb
Sugar is bad for health and for period health. High-dose fructose causes insulin resistance and inflammation and is more inflammatory than the long glucose chains of starch. That’s why some researchers have called for a ‘fructose index‘. I discuss fructose in my insulin resistance post, my PCOS post, and Chapter 6 of my book.
Whole fruit is okay, but none of us should be eating desserts, sweet drinks, fruit juice, honey, or dried fruit (including dates) on a regular basis. Type 1 (insulin-resistant) PCOS-sufferers are the most at risk and should quit sugar entirely.
Quitting sugar is a kind of low-carb diet, and I fully support it. Please see my post Why I Ask Some Patients To Quit Sugar (and What I Mean by Sugar).
Wheat is a bad carb
After sugar, wheat is the next most problematic carb. It’s mostly because of the protein gluten. Wheat and gluten are a little bit inflammatory for everyone. They’re highly inflammatory for some. If you want more information about the current state of research for wheat and gluten, please watch this video: Gluten, A Gut Feeling.
Giving up wheat is another kind of low-carb diet, and I fully support it.
Beyond sugar and wheat
You’ll probably feel better coming off sugar and wheat. Almost everyone does. Does that mean you should go on to avoid all carbs? What will that do to your periods?
It depends on these three things:
- Do you have insulin resistance?
- Do you have digestive problems?
- Do you suffer stress or HPA (hypothalamic-pituitary-adrenal) dysfunction?
Insulin resistance may require a low carb diet
If you have insulin resistance, then you may have insulin resistant (Type 1) PCOS. You’ve essentially lost your periods to a high-carb diet. To reverse PCOS and get your periods back, you first want to quit sugar and wheat (don’t miss this step!). You may then progress to temporarily reduce (not eliminate) other carbohydrates. According to a new review paper, a low carb diet is the best way to improve sensitivity.
You shouldn’t need to go below 75 – 100 grams of carbohydrate per day. You’ll want a low-carb higher-protein breakfast and lunch, and then a small portion of starch with dinner (along with protein, fat, and veggies, of course). Starch with dinner creates satiety and prevents night-time snacking. It can also promote sleep.
Once you no longer have insulin resistance, you can go back to eating some starch.
Tip: Do you know if you have insulin resistance? Ask your doctor to test fasting insulin (not just fasting glucose). Your insulin should be less than 60 pmol/L (10 mu/L). You can also use a blood test called HOMA-IR index, which is a ratio between fasting insulin and fasting glucose. Higher insulin means insulin resistance.
Tip: To be successful with a low carb diet, you’ll need more fat. Fat maintains satiety and energy and promotes healthy periods. Good fat sources include avocado, butter, coconut oil, and olive oil.
If you have Type 2 or 3 (non-insulin-resistant) PCOS, please do NOT cut all carbs. To do so may banish any hope of restoring your period. You can still cut sugar and wheat.
Digestive problems may temporarily require a low FODMAP diet
If you have digestive problems, your periods may benefit from temporarily reducing certain types of carbohydrates, such as hard-to-digest FODMAPs in fruit and wheat.
FODMAPs cause digestive bloating and inflammation in some people. That inflammation can cause period problems such as pain and irregularity.
FODMAPs are more likely to be a problem if you suffer a digestive problem called SIBO (small intestinal bacterial overgrowth). Fortunately, you can treat SIBO with a short course of a herbal antimicrobial such as berberine. Berberine and other herbs were trialed for SIBO in this recent John Hopkins study. Once your digestion has improved, you should be able to reintroduce fruit.
Tip: I have seen a long-term low carb diet cause constipation in some people. I don’t know why it happens, but it always reverses with the reintroduction of some starch.
Starch to reduce your stress response
As I describe in my Gentle Carb post, starch is calming and boosts the valium-type neurotransmitter GABA. It also helps to regulate you HPA (hypothalamic-pituitary-adrenal) axis.
If you have a robust HPA axis, you might be able to get away without a lot of starch.
If on the other hand, you suffer stress or anxiety or sleep problems, you may feel worse on a starch-free diet. And stress is not good for periods. Try reintroducing some starch and see how you feel.
Have you tried a low carb diet? What happened with your periods?