It might seem like everyone you know is doing some version of intermittent fasting, an eating pattern where you restrict food to certain hours of the day (usually a 6- or 8-hour window) or days of the week (often skipping or extremely reducing intake two days out of the week), and talking nonstop about the physical and mental health benefits. Some people are even doing longer fasts that last for several days.
The science behind fasting
There are lots of reasons that someone might want to fast, says Christina Wakefield, a health coach at Parsley Health in Los Angeles. One is weight loss; when you’re in a fasted state, you switch from burning glucose for fuel to burning fat, she explains. People also fast for a cognitive boost, to improve insulin sensitivity, to promote digestive health, and to fight inflammation. A recent review in the New England Journal of Medicine reports that during fasting, cells activate pathways that build up their defenses against stress, and then when you eat again, your cells switch into a state of adaptability. This flipping back and forth seems to be good for your metabolic health the article reports. The paper also states that intermittent fasting could potentially help against obesity, diabetes, cardiovascular disease, cancers, and neurodegenerative brain diseases. Longer fasts may activate autophagy, which is when the body clears out damaged cells to make room for new ones, Wakefield adds. And, of course, people also fast for spiritual reasons; different forms of fasting are practiced as part of many religions.
Is fasting good for you?
While it’s a powerful tool, not everyone should fast. Taking a purposeful break from food is a type of stress on your body, says Wakefield, so if you suffer from chronic fatigue or thyroid or adrenal issues, want to maximize fertility, are pregnant or breastfeeding, or are just going through a particularly stressful time in life, it’s not a good time to fast. And fasting can be triggering for people who struggle or have struggled in the past with eating disorders. It’s best to check with your doctor before beginning a fast. Parsley Health doctors and health coaches may recommend different types of fasts, or that you abstain from fasting, based on your medical history and goals.
Best foods for breaking a fast
If you decide to fast, you’ll want to be mindful of what you eat at that first post-fast meal. This will help you get the maximum benefit from your fast and come out of it feeling well. You want to avoid sending your blood sugar on a rollercoaster with refined or processed carbs, and instead want to set “an optimal blood sugar tone for the day,” says Wakefield, which will give you steady energy. If you’re at the end of the fasting portion of an intermittent fasting cycle and starting your feeding window, you want a blood sugar balancing meal that includes protein, fat, and fiber, explains Wakefield. For protein, include easier to digest sources like fish or poultry, keeping the portion size to about 4 ounces, or the size of the palm of your hand. If you’re vegan, a clean plant-based protein powder or chia pudding can be an excellent source of post-fast protein. For fat, include a few tablespoons of healthy oils like olive oil, a scoop of almond butter, or half an avocado, and for fiber, about two cups of cooked leafy greens and other vegetables or a few tablespoons of flax or chia seeds. The probiotics in fermented vegetables can also help your digestion after a fast, Wakefield adds. According to a recent review in the journal Nutrition, lowering the glycemic index of your breakfast could improve your blood sugar control after the meal. So if you’re including a carb in your post-fast meal, include one that’s lower glycemic and limit the portion size to ½ cup to avoid that blood sugar spike, suggests Wakefield.
If it’s been more than 24 hours since you last ate, you might start fantasizing a giant, indulgent meal to break the fast. But resist the temptation to go straight for the steak and potatoes, and instead start with some bone broth or a smoothie. Then, later on, add some cooked vegetables and easier-to-digest proteins, advises Wakefield. That’s because after fasting for an extended period of time, your body may have slowed the production of digestive enzymes. (Don’t worry, they’ll come back!) If you eat something that’s too heavy like red meat, or hard to digest like raw vegetables, you could end up feeling bloated or have other stomach issues. (If you do choose one of these foods, Wakefield recommends supplementing with digestive enzymes or some raw apple cider vinegar diluted in water—1-2 tablespoons per 6-8 oz of water, 15 minutes before eating.)
And don’t forget to drink plenty of water! If you’ve done a prolonged fast, replenish your electrolytes with a squeeze of lemon and a pinch of Himalayan sea salt, too, says Wakefield.
Practicing mindfulness is always important when you eat, but when you’re ending a fast it’s especially crucial to pay attention to what Wakefield calls “mindful eating hygiene.” That means focusing on your meal instead of distractions like TV or other screens. “Take a few deep breaths before you eat, to signal to your body that you’re calm and that it can prioritize digestion,” she says. Eat slowly, chewing each bite 20 to 30 times, to help your digestive system properly break down the meal and prevent bloating and other forms of digestive distress.