The Do's and Dont's of Intermittent Fasting

Fasting isn’t a new concept—many religions have practiced it for centuries. But it has become increasingly popular as a way to lose weight and improve overall wellness. Some preliminary studies also suggest intermittent fasting may help reduce the risk of diabetes, heart disease, and certain cancers. Read on to see if fasting is right for you—and how to do it safely.

Intermittent fasting has different options—from skipping one or two meals a day, to reducing your daily calories by 75 percent, to consuming nothing but water for 16 to 36 hours. Talk with your healthcare provider before you begin and decide together what makes the most sense for you.

Fasting isn’t for everyone, especially those with chronic illnesses (like type 1 or 2 diabetes) or a history of eating disorders, according to Anne Brock, RDN, LD, a specialist in weight loss and diabetic education in Caldwell, Idaho. Children, teens, and pregnant or nursing people should avoid intermittent fasting, as well.

The day before starting a fast, avoid overindulging in a fatty-but-filling meal like a burger and fries. Instead, fuel your body with slow-burning nutrients. “Get some carbohydrates, protein, and unsaturated fats to ensure you’re getting nutrient-dense foods, rather than a high-fat meal right before fasting," suggests Brock.

Proper hydration is key during a fast. It can also help curb hunger. In addition to drinking water, you’ll need to replace the hydration you'd normally receive from water-dense foods. 

Still feeling those hunger pangs? Sip plain tea, black coffee, diet soda, or another low-calorie drink to keep your stomach from feeling too empty.

You'll want to avoid any high-intensity workouts during a fast, but light-to-moderate exercise may actually be beneficial. 

One review, published in Nutrients in 2020, looked at the effects of resistance training combined with various intermittent fasting protocols. The review found that, generally, intermittent fasting combined with resistance training helped maintain lean body mass while promoting fat loss.

Intermittent fasting affects everyone differently, so it’s important to listen to your body. If you feel dizzy or weak, or if your fast is affecting your ability to complete everyday functions, stop. According to Brock, “It’s important for people to keep in mind that they may feel fatigued, irritated, distressed, depressed, and confused on fasting days."