It’s certainly not for everyone, though. As we’ve reported before, intermittent fasting could potentially be a bad choice if you’re prone to anxiety, have a history of eating disorders, or you’re dealing with one of these issues. But what about during pregnancy? If you’re a die-hard intermittent faster and you get pregnant, do you have to give up this lifestyle or might there actually be some perks like improved energy levels and reduced risk of gestational diabetes? Amy Shah, M.D., an integrative physician who personally practices reverse intermittent fasting (aka circadian rhythm fasting), feels similarly. “Intermittent fasting during pregnancy is not something I would ever recommend,” she says. “But, if you are someone who fasts regularly and want to continue it at a much lower level during pregnancy, I would be willing, as a doctor, to support and guide you.” So, why exactly is intermittent fasting—which can run the gamut from eating during a daily eight-hour window (called 16:8 fasting) to eating only every other day—a no-go during pregnancy? For one, “fasting promotes fat burning, but women in pregnancy are supposed to be creating and storing fat, not burning it,” says Gersh. This could lead to inadequate weight gain of the growing fetus and hormonal imbalances that could cause significant harm. Fasting can also create a brief time of hypoglycemia (very low blood sugar) while the body is trying to change from a glucose-burning state to a fat-burning state, which is bad for the fetus even if happening briefly. The fact is, Gersh says, “fasting is a metabolic correction process, and pregnancy creates a new metabolic reality not suitable for the fasted state.” Additionally, while fasting is good for the immune system in general, it actually lowers immune function for a period of time. And, as women who are pregnant have reduced immune function already, lowering it further is not a good idea—“Pregnant women cannot gamble on getting ill,” warns Gersh. Finally, women who are pregnant often have sluggish digestive systems and are prone to nausea and constipation. For them, Gersh says, eating small meals, and eating them more frequently throughout the day, can help them digest and absorb their food better, while fasting may exacerbate these issues. You can also promote a healthy metabolism and balanced blood sugar, and potentially avoid a complication like gestational diabetes, by prioritizing your morning meal and nixing late-night snacking. “The only timing rules that should be followed during pregnancy are to eat breakfast and to not eat after 8 p.m.,” says Gersh. To boost health during pregnancy, Shah says you can also ramp up your intake of vegetables, fruits, and nuts and scale way back on refined sugars and processed foods (for more details, here’s a nutritionist’s take on what you should eat in a day when you’re pregnant). But you still need to be careful, as intermittent fasting can stress the body and contribute to fertility struggles if done too aggressively. “Women are advised to watch for any changes to their cycle—if there are, that might mean your fasting plan is too aggressive.” In that case, scale back on your daily fasting window until you find your sweet spot. Many people do well on a 16:8 fasting plan, which includes fasting for 16 hours and confining your eating to an eight-hour window, but you may need to start more gradually (say, a 10-hour eating window) and work your way up from there to one of these intermittent fasting plans.
