Keto And Cramps: Why Periods Hurt More

The keto diet is a popular, high-fat, very low-carb approach to weight loss that has been linked to a host of health benefits. However, it can also have a strange effect on a person's period. Some women who follow the keto diet report irregular periods, while others say their monthly cycle vanished altogether—a phenomenon called amenorrhea. In fact, in some research, 45% of female participants reported menstrual dysfunction. So, why is this happening?

Weight loss and hormonal changes

The keto diet is known to aid weight loss, but rapid weight loss can also lead to hormonal changes that affect the menstrual cycle. Estrogen, for example, is stored and produced by fat cells, so when the body rapidly burns fat, it can cause a dip in estrogen levels. This, in turn, can cause menstrual irregularities and even amenorrhea (the loss of menstruation).

A sharp drop in carbohydrates can also affect thyroid hormone production, which is linked to reproductive health. A 2007 study found that a low-carb diet increased cortisol levels compared to a moderate-fat, moderate-carb diet, though this was only tested on obese men.

The keto diet can also lead to calorie restriction, which can interfere with the female reproductive cycle. This is partly because the body needs a certain level of leptin, a hormone produced by fat cells, to maintain normal menstrual function.

In addition, rapid weight loss can cause the release of stored hormones and toxins, which can also affect the menstrual cycle.

Calorie restriction

However, it is important to not restrict your calories too much. This can trigger a stress response in your body. If you are not eating enough, your body will see this as a stressor, and elevated cortisol will throttle your progesterone levels, which may lead to a missed period. This is a red flag to evaluate and adjust your calorie intake.

On a ketogenic diet, you will likely end up eating fewer calories each day. While this can be great for fat loss, when calories are reduced significantly, it can impact the hormone leptin. Leptin is responsible for signalling to your brain that you have enough energy coming in from food. When leptin is in range, it tells your body that it is safe to reproduce. However, when energy intake is low, leptin signalling dials down, and as a result, your brain gets the message that it is not a safe time for reproduction. The result is something called hypothalamic amenorrhea.

Weight loss on a ketogenic diet is determined by calories, just like any other diet. If you are not losing weight, you may be consuming too many calories. To get an idea of how many calories you should be eating, you can use a keto calculator.

Thyroid function

Research suggests that a ketogenic diet may lead to a decrease in T3 levels compared to a high-carbohydrate, low-fat (HCLF) diet. This reduction in active thyroid hormone has raised concerns about potential impairments in thyroid function. However, it is important to note that the body's response to thyroid hormones is primarily dependent on intracellular concentrations rather than circulating levels.

One hypothesis suggests that the decrease in T3 levels during a ketogenic diet may be due to improved thyroid hormone sensitivity. In other words, the body can function effectively with lower T3 levels because it has become more responsive to these hormones due to beneficial changes in cell structure and function when in nutritional ketosis. This improved sensitivity means that the thyroid gland and liver don't have to work as hard to maintain normal thyroid function.

Additionally, studies have shown that a well-formulated ketogenic diet can improve insulin sensitivity and increase the brain's sensitivity to the satiety hormone leptin. These improvements in hormone sensitivity support the hypothesis that a ketogenic diet may lead to enhanced thyroid hormone sensitivity rather than impaired thyroid function.

Furthermore, there is limited evidence to suggest that a ketogenic diet directly causes impaired thyroid function (hypothyroidism). Large randomized controlled trials have not reported any new cases of hypothyroidism among participants following a low-carbohydrate or ketogenic diet. While some individuals may be more susceptible to thyroid issues when adopting a low-carbohydrate diet, the available data does not indicate a strong link between the keto diet and significant thyroid dysfunction.

It is worth noting that a dramatic drop in carbohydrate intake can potentially affect thyroid hormone production. For individuals susceptible to thyroid-related issues, this could indirectly impact the menstrual cycle. Therefore, it is recommended to gradually reduce carbohydrate intake and monitor any changes in thyroid function. Maintaining a minimum of 50 grams of carbohydrates per day should be sufficient to support thyroid health while still allowing most people to remain in a state of ketosis.

In summary, while a ketogenic diet may lead to a decrease in T3 levels, it is primarily due to improved thyroid hormone sensitivity rather than impaired thyroid function. The available research does not provide strong evidence of a direct link between the keto diet and hypothyroidism. However, for individuals with existing thyroid issues or those who are susceptible, a gradual approach to carbohydrate restriction and regular monitoring of thyroid function are recommended.

Stress

Chronic stress can disrupt the natural rhythm of cortisol, resulting in either high or low levels of the hormone. Both conditions can negatively impact blood sugar, blood pressure, immune function, sleep, and other vital aspects of health, including mental health. High chronic stress levels have been linked to an increased risk of type 2 diabetes, depression, and high blood pressure.

The transition to a ketogenic diet can be stressful for many people. Physically, the body undergoes a shift in metabolic functions and sources of fuel, which requires a lot of energy. Psychologically, following a strict diet can be challenging and may significantly impact family and social life. This stress can further contribute to menstrual irregularities such as painful periods, irregular bleeding, and missed periods.

Additionally, when the body is under stress, it may not be in the optimal condition for reproduction. As a result, the reproductive system may slow down, leading to menstrual irregularities.

While the transition to keto may initially cause stress and menstrual irregularities, most women find that their cycles return to normal within a few months. As the body adjusts to its new way of operating, the menstrual cycle usually regulates itself.

Nutritional deficiencies

Firstly, the keto diet is a very low-carb approach, and a drop in carbohydrates has the potential to affect thyroid hormone production. For those susceptible to impaired thyroid function, this could impact the menstrual cycle.

Secondly, the keto diet can lead to rapid weight loss, which can cause a decrease in estrogen levels. Estrogen is responsible for regulating the menstrual cycle, so a drop in estrogen can lead to irregular periods or amenorrhea (loss of menstruation).

Thirdly, the keto diet can affect the release of stored hormones and toxins in the body. Adipose tissue stores various substances, including hormones, pollutants, and toxins. During weight loss, these substances are rapidly released into the bloodstream, which can affect the hormonal balance and, consequently, the menstrual cycle.

Finally, the keto diet may not provide sufficient calories, which can trigger a stress response in the body. Elevated cortisol levels can affect progesterone levels, leading to missed periods.

It is important to note that nutritional deficiencies are not the only factor contributing to menstrual irregularities on the keto diet. Other factors include hormonal changes, individual differences, and stress. However, ensuring adequate nutrition and a gradual transition to the keto diet can help mitigate the impact on the menstrual cycle.

Frequently asked questions