Intermittent fasting (IF) has been shown to help with weight loss, boost immunity, and even prevent disease, but before you dive in, you should know that IF may affect women's bodies differently from men's, and adjusting your plan for those factors could be the key to reaching whatever goals you've set for yourself.
Before we get into that, let's go back to basics. IF isn't so much a diet as a lifestyle. Rather than eliminating specific foods from your diet or cutting calories, you simply reduce the window in which you eat during the day. There are several methods for doing this, including the 12:12 ratio — eating for 12 hours, then fasting for 12 hours overnight — which is considered best for beginners. Stricter plans include 14:10 (eating for 10 hours) and 16:8 (eating typically from noon to 8 p.m.).
Liz Josefsberg, an NASM-certified personal trainer and weight-loss and nutrition expert for The Vitamin Shoppe, explained that this is done to help the body repair cells and aid hormone levels to access stored fat more easily.
So, How Is Intermittent Fasting Different For Women?
"There is some research that suggests that fasting may not be as effective or beneficial for women as men," Liz told POPSUGAR. "This is because women's bodies are very sensitive to calorie restriction." A study published in Obesity Research found that some women may actually have worse glucose tolerance after doing IF than men, and research in the Journal of Endocrinological Investigation showed that a disruption in the release of reproductive hormones can occur during a low-calorie diet, resulting in hormonal imbalances and an unpredictable menstrual cycle.
But that doesn't mean IF is off the table entirely, Brittany Michels, a registered dietitian for The Vitamin Shoppe, told POPSUGAR. "Women tend to find more success and less hormonal effects by following shorter fasting windows, such as 12 to 14 hours," she said.
How Can You Practice Intermittent Fasting Safely?
First, assess your stress levels. "The act of fasting is additional stress on the body, which can cause negative effects," Brittany said, including symptoms like missed periods. "Those who have started a fast and begin to notice signs of hormonal imbalance should modify or stop fasting. Modification could mean anything from increasing the daily eating window to only fasting one day per week."
To start, you might try a 12:12 plan and work your way up to 16:8 — skipping breakfast and restricting eating to an eight-hour window, which many of Brittany's clients find easy to follow. If shedding pounds is the goal, eat the fewest number of calories you'd need to maintain your weight during those eight hours (also known as maintenance calories). If you simply want to be healthier, aim to make up for that missed meal during this window, even if that means going over your maintenance calories. And remember to take into account your lifestyle before starting a plan. "Someone who works from 12 p.m. to 8 p.m. with one 30-minute meal break wouldn't be the best candidate for a 16:8 IF window," Brittany said. "They'd probably find more success on a 13:11, as they'd be able to eat breakfast before work and lunch at work."
Whatever your plan, start slowly. Liz suggests pushing eating back by an hour every two to three days until you find the perfect ratio. "When you're eating, limit carbs and push meals more toward high amounts of healthy fat and protein," she said.