• Allison Fahrenbach

The Keto Diet & Women

I thought I'd take the time to address the VLCD diet trend particularly as it applies to women and female health.

A lot of women, including athletes, are embracing or experimenting with very low carbohydrate diets, and in particular, keto.

This isn't new.

Keto has been around since the 1920s, and while yes, keto can be effective, it's NOT for everyone.

And it DOES impact women differently then men- often, negatively.

Evidence suggests that women’s hormones are more sensitive than mens to energy availability, meaning that too few calories or carbs can cause imbalances.

But first - what IS a keto diet?

A ketogenic diet is a very low carbohydrate, moderate protein and high fat based nutrition plan that trains the individual’s metabolism to run off of fatty acids or ketone bodies. This state of ketosis, or being fat adapted has been shown to improve insulin sensitivity and reduce inflammation. It also improves cellular healing and mitochondrial biogenesis which supports stronger and healthier cells- all of which helps lead to a reduced risk of chronic disease, improved muscle development and more efficient fat metabolism.

But as I said, it's not for everyone.

For example men and women, in my experience don't respond the same to very low carb diets. The stress of very low carb dieting is much better handled by men, whereas in women, particularly female athletes performing at high levels of activity or intensity I notice some pretty negative effects.

One has to do with adrenal function. VLCD approaches impact the HPA axis, which is comprised of three major glands, the hypothalamus, the pituitary, and the adrenals.

These glands are responsible for hormonal regulation and impact mood, emotions, digestion, immune system, sex drive, energy levels, metabolism and more. These glands also happen to be sensitive to things like stress, exercise AND calorie intake.

The body can't differentiate between the type of stress it's encountering. So it doesn't matter if it's exercise, diet, or a fight with your spouse, it all impacts these glands the same.

Long-term stress, like the kind endured during a VLCD can cause you to overproduce the hormones cortisol and norepinephrine, creating an imbalance that increases pressure on the hypothalamus, pituitary and adrenal glands.

This ongoing pressure may eventually lead to HPA axis dysfunction, also sometimes controversially referred to as “adrenal fatigue” or can cause the onset of symptoms that mimic adrenal fatigue, like a weakened immune system, depressed thyroid function or greater risk of long-term health problems such as hypothyroidism, diabetes, heightened anxiety, erratic mood, or sleeplessness.

Some evidence has suggested that VLC diets (under 100g a day) can cause increased production of cortisol (stress hormone) which makes matters worse since cortisol increases body fat.

A 2007 study found that, regardless of weight loss a VLC diet increased cortisol levels compared to a moderate-fat, moderate-carb diet.

So basically, if I have a female client who works a high stress job or has a lot of responsibilities via her family, etc, I definitely would think twice before implementing a low carb diet or keto approach.

Being really lean is also something to watch for, as the leaner you are the more intolerant your body becomes to stress. This is because, as a woman, carrying super low levels of bodyfat is a stress in and of itself.

Lean women who are under stress, do high intensity training and are on a ketogenic diet are, IMO, creating a state of chronic stress that the body is just not able to handle. If you're hell bent on going VLC I would suggest cycling out of ketosis, using a carb up day, reducing training load and improving rest, along with using things like adaptogenic herbs and B vitamins to help you to recover more effectively.

Another thing to consider is the impact carbs have on the thyroid. I never suggest a VLCD to someone with hypothyroidism. Never.

I have done cyclic keto with some hypothyroid clients- but honestly a moderate carb approach always works better. The reason being that the thyroid gland produces two hormones: thyroxine (T4) and triiodothyronine (T3) which are both necessary for a wide range of bodily functions (breathing, heart rate, nervous system, body weight, temperature control, cholesterol levels and menstruation.)

T3 is very sensitive to calorie and carb intake. If calories or carbs drop too low, two things happen: 1)T3 levels drop and 2) reverse T3 (rT3) levels increase (rT3 is a hormone that blocks the action of T3).

Some studies have shown that ketogenic diets can reduce T3 levels, as much as 47% in just two weeks of a sub 50g carb a day diet. By contrast, people consuming the same calories but at least 50g carb a day saw no drop in T3. This matters a lot because low T3 and high rT3 can slow your metabolism, resulting in weight gain, fatigue, lack of concentration, depression and so on.

Being VLC can also cause the loss of a woman's cycle. Amenorrhea is what's known as a woman’s menstrual cycle being absent for 3 months or more and the most common causes are low calories, low carbs, stress, or too much exercise. Women need a certain amount of leptin to maintain menstrual function. If your carb or calorie consumption is too low, it can suppress leptin levels and interfere with leptin’s ability to regulate the reproductive hormones. This is particularly true for underweight or lean women who are also on a VLCD.

Now some women could care less about losing their period, particularly if they aren't trying to conceive, but keep in mind that the loss of your period causes OTHER issues. Amenorrhea results in a domino effect, causing a drop in the levels of other hormones such as luteinizing hormone (LH), follicle-stimulating hormone (FSH), estrogen, progesterone and testosterone. And NONE of this comes without ramification in the body.

Granted everyone is different- I firmly believe that, and optimal carb intake varies greatly between one person and the next. There is no one-size-fits-all solution in nutrition and how much carbohydrate you do or don't consume a day is ultimately going to be (or should be) based on individual factors.

But in general I think VLCD or keto diets should only be used for very overweight or obese individuals, those who are more sedentary, have insulin resistance, have PCOS or fibroids, or have diabetes.

I prefer a more moderate carb approach for:

  • high level athletes

  • women who are very active and struggle to recover after training

  • women who are very lean

  • women who have an underactive thyroid

  • women who struggle to lose weight or start gaining weight, even on a low-carb diet

  • those who have lost their period or have irregular periods

  • women who are pregnant or want to be

  • women who are breastfeeding.



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