Hi everyone,

Intuition often leads us to believe that putting two good things together makes a great thing.

For instance, studies suggest that intermittent fasting and exercise prolong lifespan, and it may seem like doing both could be even more effective for lifespan, right?

Ahhh, but this may not necessarily be true. 

In this newsletter:

• Fasting and longevity.

• The muscle loss malady.

• Consider this first.

• Resource to do it right.

• And more…

DIET + FITNESS

Intermittent fasting for longevity

Intermittent fasting (IF) is the talk of the (healthy) town.

Research suggests that this eating approach extends lifespan in animals, and aging experts are sure that the longevity-boosting benefits are translatable to humans.

⏱️ IF works by restricting a person’s eating window to a set amount of time. An IF can be done routinely or cyclically.

• Alternate-day fasting oscillates between normal and restricted eating patterns over a few days. It follows a feast and famine cycle, in a sense (i.e., eating 25% of daily calories on fasting days).

• Time-restricted eating limits food intake to a certain number of hours each day. The 16:8 is a popular routine (16-hour fast and 8-hour eating window).

Despite the numerous potential health benefits—from weight loss and reversing diabetes risk to reversing chronic disease and targeting cancer cells—intermittent fasting (IF) could cause lean muscle mass loss, which is detrimental to healthy longevity.

The muscle loss malady

💪 Muscle is closely linked with longevity because it helps protect everything in the body, from the heart to the bones and brain and beyond.

Muscle mass might just be one of the best marker of longevity, according to Dr. William Evans, an adjunct professor of Human Nutrition at the University of California, Berkeley, in an interview with InsideTracker.

It determines the efficiency of functions such as walking speed, grip strength, and bone fracture risk, Evans explains.

• “It appears that in very old adults, muscle mass is more strongly related to the risk of a hip fracture than is their bone density,” Evans says.

More than a decade of research suggests that getting treated for a hip fracture is significantly associated with short-term mortality, so we’d love to prevent these in whatever ways possible.

The reason why fasting contributes to loss of lean muscle mass is that it limits protein consumption, particularly during the fasting window.

Protein is foundational to lean muscle growth.

This is especially relevant for older adults, who are encouraged to eat protein at a faster rate than the body breaks it down.

• Why? It is so much harder to gain that lean muscle mass in the first place.

Cutting calories (intentional or not)

Calorie restriction (whether intended or not) is also associated with fasting, and this can further contribute to lean muscle loss.

“If you skip breakfast, you will typically eat a little bit more at lunch, but you won't eat as much as if you had eaten breakfast,” says Eric Williamson of the faculty of Kinesiology and Physical Education at the University of Toronto (UT).

“That ends up putting you into a caloric deficit and, by the laws of physics, it is what leads to the loss of mass overtime.”

When you add exercise to the mix, it can be even harder to achieve muscle gains or even maintain muscle mass.

• ⬇️🥘 + 🏃= ⬇️💪

Exercise + intermittent fasting may prevent muscle gains

Exercising while intermittent fasting may not be conducive for muscle growth or strength, according to an article in Centr. 

Namely, when you practice IF, you are attempting to fit a day’s worth of protein into one or two meals, says Lisa Middleton, an advanced sports dietician in Melbourne, Australia, to Centr.

This just “isn’t as effective” for muscle growth, and workouts are fueled by the stuff, according to Centr. 

• It would better serve your workout to eat protein throughout the day, Middleton says.

• Consistent protein consumption also supports muscle retention over time, says UT’s Williamson in an interview.

As far as fasting is concerned, it’s also physiologically harder to complete a difficult workout while IF.

“While exercising in a fasted state, it's possible that your body will start breaking down muscle to use protein for fuel,” says Chelsea Amengual, MS, RD, Manager of Fitness Programming & Nutrition at Virtual Health Partners, in an interview with Healthline.

“You're more susceptible to hitting the wall, which means you'll have less energy and not be able to work out as hard or perform as well.” 

Similarly, when you are potentially restricting calories (again, whether intentional or not), your body can lose the ability to effectively build muscle and strength—as excess calories are needed for muscle growth—Centr reports. 

• Note that it’s not impossible to grow muscles, but it will not happen as quickly or effectively, according to UT’s Williamson.

Exercise also puts a certain level of strain on the body. Normally this is beneficial, since muscle growth happens from tear and repair.

However, muscles repair faster and better with consistent food and fuel in the tank ⛽, so restricting eating can make it more difficult to achieve both.

When is exercise beneficial during fasting?

Fasting without exercising can have its own repercussions– namely, it can lead to muscle atrophy (muscle wasting), according to Williamson.

• While IF, doing resistance exercises can be a practical way to preserve muscle and prevent atrophy, he says.

There is evidence which suggests that working out during an IF can boost explosive strength, endurance, and oxygen consumption, although more studies are needed to identify these specific benefits.

Should you do both?

There are few conclusive benefits to IF and exercise, although these benefits might not outweigh risks, especially in older adults, according to Matthew Lees of UT.

“Having a long period where you don't consume any dietary protein is just not conducive to skeletal muscle health in an older population,” he says in the UT article.

It is possible to still safely fast and exercise, just note that doing both is not necessarily going to lead to physical gains and better performance.

Feel free to reach out at us at [email protected] with any comments or questions.

Thought this was interesting?

That’s great! Please take a second to share this newsletter with a friend. This way, we can continue to give you fresh, actionable, and evidence-based information that supports your health and well-being.

We love to hear from you

Please share your feedback, stories, questions, testimonials, ideas, and more with us.

🔔 Catch up on last week’s newsletter

The popular golden milk beverage becomes even more healthy and nutritious.

We can’t wait to cover more trending topics in longevity in our next newsletter. Stay tuned.

-Erin

Longevity Media LLC

Be your own expert. Optimize your health. Look beyond conventional.

Always seek the advice of a physician or other qualified health care professional before starting any exercise, wellness, or health program. Nothing in our content, products or services should be considered, or used as a substitute for, medical advice, diagnosis, or treatment. Livelong is a media company and not a medical provid