Fasting: What Science Actually Tells Us (And What It Doesn’t)

If you’ve spent any time in the wellness world, you’ve probably heard that fasting is the key to everything—weight loss, mental clarity, gut health, eternal youth (okay, maybe not the last one, but people get real dramatic about it). Dr. Mindy Pelz, fasting expert, YouTube sensation, and author of Fast Like a Girl, recently joined Dr. Sara Szal Gottfried on the Treated podcast to get into fasting—what works, what doesn’t, and why your hormone cycle might be the game-changer nobody’s talking about… yet. 

Beyond the Wellness Trend

Fasting isn’t new. Your body already does it naturally—during sleep, when you’re too busy to eat, or when you get the flu and have no appetite. But the wellness industry has turned it into a performance sport, making people believe they must hit a certain number of fasting hours to “unlock” health benefits.

Dr. Pelz, who has spent years researching fasting’s impact on women, takes a more nuanced approach. “Everything that I see is always like, why is the body doing that? Because nothing that the body does is ever by mistake,” she told Dr. Szal Gottfried. In other words, if fasting is helping your body heal, great. But if it’s making you feel awful? Your body is saying, “Ma’am, I need some food.”

Does Fasting Work for Everyone?

Fasting isn’t magic. The Cleveland Clinic categorizes fasting into four main types—time-restricted eating, alternate-day fasting, 5:2 fasting, and periodic prolonged fasting—but just because it works for one person doesn’t mean it works for everyone. 

Dr. Pelz advocates for strategic fasting, especially for women. She points out that most fasting research is based on men (classic) and doesn’t account for hormonal fluctuations. “I have immense respect for the healing capabilities of the female body,” she says. “If you learn to read the clues, the body is always healing itself.”

Translation: Your cycle matters. Fasting during your luteal phase (the week before your period) can spike cortisol and make you feel like a hot mess, while fasting in the follicular phase can feel amazing. Knowing when to fast is just as important as knowing how.

The Dark Side of Fasting: When It’s Not a Good Idea

If fasting is the new health trend, skipping breakfast is its problematic older sibling. You’ve probably heard the advice to “just push through hunger,” but Mount Sinai found that skipping breakfast could harm your immune system.

Dr. Pelz knows that fasting can be game-changing for some women, but for others, it’s a stressor. “What is it that we’re not giving women permission to say, ‘I’m not okay’?” she asks. Fasting should never feel like a punishment. If you’re exhausted, burned out, or struggling with anxiety, fasting might not be the answer—it might be the problem.

What About Weight Loss?

With everyone and their mother jumping on the GLP-1 bandwagon, fasting for weight loss can feel like an old-school approach. But here’s the thing: The best weight loss strategy is one you can maintain.

“Women who fast and lose 60 pounds, they’re like, ‘I’m a badass!’” Dr. Pelz says. “People who go on Ozempic don’t have that same empowerment.” When done correctly, fasting can be a tool to reset metabolic health—but it’s not about starving yourself. It’s about balance.

The Right Way to Fast (Hint: It Involves Your Doctor)

The biggest takeaway from Dr. Pelz’s Treated episode? Talk to your doctor. Before you start skipping meals, check in with a professional—especially if you have health conditions, are pregnant, or have a history of disordered eating.

Fasting should work for you, not against you. And if you ever find yourself white knuckling your way through hunger just to hit some arbitrary goal? That’s your sign to reevaluate.

You Do You, Boo

Dr. Pelz is proof that the practice is not one-size-fits-all. It can be an amazing tool for some women and a nightmare for others. The key is listening to your body, not forcing it into some influencer-approved fasting protocol.

So before you jump on the bandwagon, ask yourself: Do I feel good doing this? Is this sustainable? And most importantly, am I taking care of myself in the process?

Because no diet, no trend, no fasting plan is ever worth sacrificing your well-being. And if anyone tells you otherwise? They might need to fast from giving advice.

Watch the full episode of Treated with Dr. Mindy Pelz below.