Hey, internet human. I’ve started my morning smoking what The Guardian likes to call a “suspicious-looking cigarette” and unsurprisingly, I felt an inspiration to write this article.
Since everyone is now fasting the crap out of themselves—you’d think—muscle loss might be an issue. So…
Hunter et al. conducted a study in 2008:
Here’s what the researchers did:
25 weeks later, because of that dumb, all too ridiculous for words 800-calorie diet, all groups lost weight but only the diet + resistance training maintained lean muscle mass while other groups lost both muscle and fat:
Now, her’s the deal, my hypothetical reader friend:
After seasickness and trying on trousers, losing lean muscle during weight loss is the worst thing in the world. I would rather go to work with a brick tied to my privates than lose hard-earned muscle (jk.)
As I always say to my clients—LOSING MUSCLE IS UNACCEPTABLE.
At this junction, you might have this question ready to blurt out:
“Egis, I’m 114 words into your ridiculously illustrated article and still can’t see a connection with intermittent fasting. Da fuck, yo?”
Hmm. Right. Here’s the connection:
That’s sort of a “well duh” statement but when you don’t eat for a prolonged time you lose muscle (who’d have guessed?). Intermittent fasting (IF) makes you fast for 16 hours (among other more aggressive approaches). You only have an 8-hour eating window. This may have a potentially unfavorable consequence of loss of lean body mass.
Until now, IF & muscle loss was just a theory. Luckily, Keenan et al. conducted the first-ever systematic review & meta-analysis on IF and lean body mass preservation:
Researchers looked at eight studies when IF and resistance training were undertaken together. The results showed that:
Okay, grasshopper, here’s a quick summary:
- It appears that IF shows no threat of muscle mass loss when resistance training is utilized alongside;
- To make sure you preserve muscle mass, you still need to get in an adequate protein intake which is 1.6-2.2 g/kg of body weight (.7-1g/lb)1;
- Mind you, this study looked at sedentary and beginner trainees. Almost any workout plan & diet you throw at them sticks. Advanced and already lean folks may likely lose muscle with IF. If that’s you, I think you’d benefit more from a spread-out meal & protein distribution throughout the day;
- IF helped to preserve muscle mass in this study. But with a more spread-out meal distribution, you may have not only preserved it but also built muscle. Because, with spread-out meals, you provide your body with a constant influx of an amino acid leucine which triggers muscle protein synthesis (the process of building new muscle.)

P.S. As I said, IF doesn’t cause special effects when compared to continuous energy restriction—unless you’re a busy chap pressured by time or you prefer fewer but larger meals, you don’t have to follow IF just because some bigoted douchebag told you that IF is the only nutrition approach that doesn’t suck.
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