When Not to Fast
Although intermittent fasting has been proven to burn body fat, ward off illness, improve brain function, and increase your energy, sometimes intermittent fasting isn't appropriate. Make sure you use common sense and consult your physician with any questions that you may have about fasting.
If you find yourself in one of the following groups, you shouldn't do intermittent fasting:
If you're pregnant or trying to become pregnant: When you're pregnant or trying to get pregnant, focus on the pregnancy. After pregnancy, if you want to try intermittent fasting, talk with your physician about whether or not fasting is a good option for you.
If you're immunosuppressed: Consult with your doctor first before doing an intermittent fast. Although some very interesting research focuses on the benefits of fasting for people undergoing chemotherapy, you should never begin fasting on your own if you're currently battling cancer, HIV/AIDS, or any other sort of immunosuppressive ailment without first garnering your doctor's approval.
If you're diabetic: Intermittent fasting has shown to positively affect insulin resistance; however, if you're diabetic, fast only under the direct supervision of your healthcare provider.
If you're under 18 years old: Studies on the effects and benefits of intermittent fasting have focused primarily on adults. For this reason, intermittent fasting is only appropriate for otherwise healthy adults and adults who have been cleared to fast by their physician.
You should always check with your physician or healthcare provider before starting any diet or fitness plan. He or she can advise you on whether intermittent fasting is a safe option for you.