Intermittent fasting (IF) is a popular way to control eating patterns by cycling between periods of fasting and eating without restrictions. According to the Cleveland Clinic, there are four ways to follow this method. They include time-restricted eating; alternate-day fasting; twice-a-week method—5:2; and 24-hour fasting. Supporters of intermittent fasting believe this is an effective way to lose weight, improve overall health by triggering metabolic changes, and some research suggests it may help a person live longer.
But how does intermittent fasting affect your strength training workouts and building muscle?
Navin Nandalall, NASM Certified Personal Trainer at New York Health & Racquet Club said, “Overall, I’m a big fan of intermittent fasting, but recommend it more for people who are sedentary. The power of IF is that it controls insulin and for insulin sensitive people trying to control their weight, this is a great method.”
Is it Safe to Strength Train While Intermittent Fasting?
Nandallal said he hasn’t seen evidence that suggests a work out while doing IF is unsafe.
A study published in the Journal of Translational Medicine split “thirty-four resistance-trained males” into two groups and tracked them. One group followed a time restricted method of eating (16:8) and the other group consumed all their calories in three meals over the course of a day. The results of the research “suggest that an intermittent fasting program in which all calories are consumed in an 8-h window each day, in conjunction with resistance training, could improve some health-related biomarkers, decrease fat mass, and maintain muscle mass in resistance-trained males.”
Is There a Right Time to Exercise During the Fasting Cycle?
According to Nandallal, “There’s no study to prove timing. But I would recommend a workout right before you break the fast. That way there’s not a lot of room for blood sugar to spike and the foods you eat right after will be used to replenish nutrients. Also, you’re going to be pulling from fat to burn energy in a fasted state, instead of glycogen.”
Research suggests eating post-training supports muscle recovery and growth. As reported in a Healthline report on intermittent fasting and exercise, Dr. Niket Sonpal, Adjunct Assistant Professor of Clinical Medicine, Department of Basic Biomedical Sciences at The Touro Collego of Osteopathic Medicine, said, “And if you do heavy lifting, it’s important for your body to have protein after the workout to aid with regeneration.” However, it’s essential to eat enough calories in a day to give you enough energy to support training performance, no matter the timing.
It’s also important to listen to your own body. Some people like to exercise on empty stomachs while other may not. It also depends on an individual’s goals.
Can You Build Muscle if you do Intermittent Fasting?
To build muscle the body needs to be in a surplus of calories and have enough protein. IF makes it a little harder to do because you have a shorter period to get your nutrients, but it’s not impossible, said Nandallal.
What to Consider
In order to build muscle and get maximum gains from your strength training routine, it’s important to consume enough calories. If you want to follow an intermittent fasting plan, also take into consideration timing of post-exercise snacks to support recovery to get optimal results from your workouts and reach your fitness goals.