Intermittent fasting (IF) is more than just a trend—it’s a wellness strategy that has gained popularity for its potential to improve metabolic health, support weight loss, and promote longevity. But like all health protocols, it’s not without controversy. At Amethyst Wellness, we believe in personalized, evidence-informed approaches—so let’s take a balanced look at the pros and cons of intermittent fasting, featuring insights from health leaders Mark Sisson and Dr. Stacy Sims.
The Pros of Intermittent Fasting
(with insights from Mark Sisson, author of The Primal Blueprint)
Mark Sisson, a leading voice in ancestral health and founder of Primal Kitchen, advocates for intermittent fasting as a way to align modern life with our evolutionary biology:
“Intermittent fasting isn’t about starving yourself. It’s about giving your body a break from the constant barrage of calories so it can tap into fat stores, repair itself, and function optimally.” – Mark Sisson
1. Enhanced Fat Burning
Fasting shifts the body toward using fat for fuel. As Sisson notes, this metabolic flexibility helps you become a “fat-burning beast.”
2. Improved Insulin Sensitivity
Time-restricted eating can reduce insulin resistance and help regulate blood sugar—essential for metabolic health and weight control.
3. Supports Cellular Repair
During fasting, the body initiates autophagy, a cellular clean-up process that removes damaged cells and supports longevity.
4. Cognitive Benefits
Some people experience heightened mental clarity and energy during fasting periods, likely due to stable blood sugar and increased ketone production.
5. Simplifies Eating
No need for calorie counting or meal prepping all day—many find the minimalist structure of IF easier to maintain.
The Cons of Intermittent Fasting
(with insights from Dr. Stacy Sims, PhD, author of ROAR)
Dr. Stacy Sims, an expert in exercise physiology and female-specific nutrition, cautions against a one-size-fits-all approach to fasting—especially for women:
“Women are not small men. The research supporting intermittent fasting largely excludes premenopausal women, and the hormonal impact can be significant.” – Dr. Stacy Sims
1. Hormonal Disruption in Women
Sims warns that intermittent fasting can negatively affect estrogen, progesterone, and cortisol levels—potentially leading to irregular cycles, fatigue, and sleep disruption.
2. Stress Response
Fasting can increase cortisol (the stress hormone), especially in active women or those under high mental/emotional load, amplifying symptoms of burnout and adrenal fatigue.
3. Energy and Mood Swings
In the early stages of fasting, many experience low energy, mood swings, or brain fog, especially if fasting windows are extended too aggressively.
4. May Hinder Muscle Maintenance
Fasting combined with inadequate protein or poorly timed workouts can compromise lean muscle mass, particularly in midlife women.
5. Not for Everyone
Intermittent fasting is not recommended for those who are pregnant, breastfeeding, managing thyroid issues, or have a history of disordered eating.
Finding the Right Fit for You
Intermittent fasting can be an empowering tool for metabolic and cellular health—but it’s not the best strategy for everyone. At Amethyst Wellness, we help you navigate personalized nutrition based on your unique needs, hormones, and lifestyle goals.
Curious about intermittent fasting or feeling frustrated with weight loss plateaus? Schedule a consultation or meet with our health coach and let’s create a plan that works with your body—not against it.