Fast Like a Girl

In Fast Like a Girl, Dr. Mindy Pelz, a chiropractor and wellness author, offers a fasting guide written specifically for women. She argues that while time-restricted eating can help, women should adjust how long they fast and what they eat to the hormonal changes of the menstrual cycle (estrogen, progesterone and others).

Pelz's Cycle Phases#

Pelz divides a typical cycle into four phases, each with its own fasting and food advice:

1. 1.Power phase (days 1–10): Estrogen is building. Pelz argues estrogen does best with low insulin and low cortisol, and recommends longer fasts and lower-carb eating here.
2. 2.Manifestation phase (days 11–15): Around ovulation, estrogen peaks and testosterone rises. She recommends shorter fasts (under about 13 to 15 hours) and hormone-supporting foods.
3. 3.Second power phase (days 16–19): A return to longer fasts and lower-carb eating.
4. 4.Nurture phase (day 20 until your period): Progesterone rises. Pelz argues progesterone needs more glucose and is sensitive to stress, and advises against fasting in this phase.

Pelz suggests fasts of 13 to 72 hours in the power phases. Talk to your doctor before fasting for more than a day, and don't if you're pregnant, breastfeeding, diabetic, underweight or have a history of eating disorders. Cycles also vary in length, so her day counts are only a guide.

How This Connects to ARC#

ARC doesn't track menstrual cycles or fasting. What it can do is keep the rest of your day's timing steady: about 20 minutes of morning light from your real sunrise, a caffeine cutoff computed from each drink you log, and a wind-down reminder before bed. For the research on meal timing more broadly, see our circadian fasting guide. ARC is a wellness app, not a medical device. ARC isn't affiliated with or endorsed by Dr. Pelz; this summary is our own.

ARC isn't affiliated with or endorsed by Dr. Mindy Pelz or the publisher. This summary is our own reading of the book. Educational content, not medical advice.