Intermittent Fasting Isn’t One-Size-Fits-All — An MD Explains Why
Intermittent fasting is often framed as a simple formula: stop eating at a certain time, wait a set number of hours, and the benefits will follow. But in reality, the body doesn’t respond to rigid rules so neatly. What helps one person feel focused and energized can leave someone else depleted, hungry, and struggling to recover from workouts.
On the mindbodygreen podcast, board-certified OB-GYN and mindbodygreen scientific advisor Jaime Seeman, M.D., offers a more nuanced perspective on one of the most talked-about trends in nutrition: fasting.
Rather than treating intermittent fasting as a universal solution, Seeman encourages women to think of it as a flexible tool that should adapt to their goals, training demands, and life stage.
“Fasting is just a tool,” Seeman explains. “We have to always put this in the context of what the goal is.”
And in her clinical experience, many women focus too much on the fasting window itself and not enough on what actually matters for metabolism, muscle, and long-term health.
Why fasting works for some women, but not all
At its core, fasting simply means going for a period of time without eating. In fact, most people fast overnight while they sleep. Structured fasting protocols, such as time-restricted eating, extend that natural break between meals.
But Seeman says the conversation around fasting often becomes overly rigid. Instead of asking whether fasting is “good” or “bad,” she encourages women to start with a more important question: What are you trying to achieve?
Some people use fasting for convenience. Seeman herself occasionally delays breakfast because her mornings are packed between 5 a.m. and 9 a.m. Others experiment with fasting to support metabolic health or simplify their eating schedule.
Where fasting can go wrong
The issue, Seeman says, is that many people start stretching their fasting windows without considering whether they’re still meeting their body’s basic nutritional needs.
“We have to balance fasting with feasting,” she explains.
That means paying attention to what happens during the eating window. Are you getting enough protein to support muscle maintenance? Are you consuming enough calories for your activity level? Are you meeting your micronutrient needs?
For active women, this question becomes especially important. Long fasting windows can sometimes lead to under-fueling, particularly for those who train regularly or have demanding lifestyles.
And when the body consistently receives too little energy, performance, recovery, and hormone health can begin to suffer.
What happens during your eating window
While fasting protocols often focus on the hours spent not eating, Seeman says the quality and quantity of food consumed during the eating window matters far more.
Protein intake is a major priority, especially for women who want to preserve lean muscle mass as they age. Adequate protein supports muscle repair after workouts, helps regulate appetite, and plays a role in metabolic health.
Total calorie intake matters too. If someone compresses their meals into a small eating window but unintentionally eats far less than their body requires, fatigue, stalled progress in the gym, and increased cravings can follow.
The types of foods chosen also play a role. Whole, nutrient-dense foods provide vitamins, minerals, and amino acids that support metabolic function and recovery. Simply shortening the eating window without improving food quality doesn’t necessarily improve health outcomes.
In other words, the eating window should still look like a balanced day of nutrition.
How to decide if fasting makes sense for you
If you’re curious about intermittent fasting, Seeman suggests approaching it as an experiment rather than a rule you must follow. A few guidelines can help you determine whether it’s actually working for your body.
- Start with your goal. Before choosing a fasting window, clarify what you want to accomplish. Are you trying to simplify your routine, improve metabolic markers, support fat loss, or maintain weight? The goal should guide the strategy.
- Make protein a priority. Ensure your meals contain adequate protein to support muscle maintenance and recovery. This is especially important for women who lift weights or exercise regularly.
- Match calories to your activity level. Active individuals often need more total energy than they realize. If fasting leads to consistently eating too little, it may not be the right approach.
- Consider workout timing. Some people feel great exercising in a fasted state, while others perform better when they eat beforehand. If strength, endurance, or recovery suffer, adjusting your meal timing may help.
- Stay flexible. Your ideal eating schedule may change depending on stress levels, training cycles, travel, or different life phases. What works during a quiet week may not work during an intense training block.
The takeaway
Fasting has earned its place in the health conversation, but it works best when it’s treated as a flexible strategy rather than a rigid rule.
As Seeman emphasizes, the real drivers of long-term health are still the fundamentals: adequate protein, nutrient-dense foods, strength training, and enough total energy to support your body’s demands.
Seen through that lens, fasting becomes less about discipline and more about personalization. The goal is not to fast longer or harder. It’s to create an eating rhythm that supports your metabolism, your workouts, and your life.
