NUTRITION 28th February 2018

Is intermittent fasting
bad for women?

By

3 min

Intermittent Fasting (IF): the practice of going without food for prolonged periods of time, is known to do some amazing things for your body: improved weight loss, decelerated aging and better heart health – if you’re a man that is. Women haven’t been so lucky.

Background

Every time you eat, your body releases insulin (see here). In today’s world, we eat more frequently than we should, driving insulin levels up. When this happens, you store more fat and risk disorders such as type two diabetes and cancer. By contrast, when you practice intermittent fasting (IF), your body is in a fasted state for anywhere between sixteen to forty-eight hours, therefore releasing less insulin.

There are several ways to practice intermittent fasting, some of the most popular include:

  1. The 16/8 Method: Fast for 16 hours each day
  2. The 5:2 Diet: Fast for 2 days per week
  3. Eat-Stop-Eat: Do a 24-hour fast, once or twice a week

(For more information see: healthline.com)

In a fasted state, your body also has the time and space to perform a key biological process known as autophagy: the repair and recycling of damaged cells. Autophagy improves your memory and focus, reduces your risk of cardiovascular disease, restores your skin cells (thus slows down the rate of aging), and puts you in an all-around better mood.  Amazing stuff.

The female case against IF

Unfortunately, IF for women doesn’t bode so well when compared to men. Reported side effects include:

  • Irregular periods
  • Early menopause
  • Metabolic disorders
  • Sleeplessness
  • Anxiety
  • Brain fog

(Source: https://www.precisionnutrition.com/intermittent-fasting-women)

Why is this?  Because female hormones do not respond well to calorie restriction. For instance, it is well established that the menstrual cycle and fertility hormones are impacted by malnutrition. Women who are underweight are at greater risk of infertility. That said, it’s not entirely clear why female hormones reject calorie restriction more than male hormones. The most plausible explanation relates to kisspeptin: a protein produced by the hypothalamus region of your brain.

In women, kisspeptin controls the hormones which regulate ovulation: luteinizing hormone (LH) and follicle-stimulating hormone (FSH).  In men, it controls the production of testosterone. Since women produce more kisspeptin than men, theoretically this is one reason why they are more sensitive to caloric changes from IF. Studies support this notion. In the case of female mice placed on a calorie-restricted diet, they experienced a dip in kisspeptin levels and subsequently lower fertility rates.

And if you’re a woman with a weight loss goal, another study linked kisspeptin to obesity and metabolic disorders. Women are extremely sensitive to signals of starvation, and if the body senses that it is being starved, it will ramp up production of the hunger hormones leptin and ghrelin

The stress of intermittent fasting impacts women’s hormones disproportionately to what men deal with. Females should consider the risk factors outlined here and always consult their health practitioner in the first instance.

As always, pushing for health.

Photo Credit: www.musclemonsters.com