Hypertrophy at the Cellular Level- Question

Physical Culture

More than 500 posts
I have several questions regarding muscular hypertrophy at the cellular level. I'll dump them here and see who can help! Thanks!

1. How long does the process of hypertrophy last? By this I mean, do we know how long it takes the body to grow muscle when it has been stimulated? In this blog post (Intermittent Fasting: 12 Lessons Learned from 1 Year of Fasting) James Clear advocates calorie cycling. His idea is to have a positive energy balance on training days, to grow muscle, and a negative energy balance on non-training days, to lose fat. This does not make sense to me- it seems that when the body has been stimulated to grow (assuming the hormone, protein, and calorie levels are sufficient), that it should take a while to create new cells. Do we know, when the stimulus is provided and the body goes into "hypertrophy mode", how long it will take to grow muscle before the process ends and more stimulation is required to restart it?

2. It's often said that a calorie surplus is required for hypertrophy. Is this true? If the body has been stimulated to grow muscle through resistance training/endocrine system stimulation, can it used stored energy (adipose tissue) to fund the hypertrophy process? For example, if fasting into the state of autophagy, can the body use the cells it breaks down to pay for hypertrophy? Or does hypertrophy only occur through energy ingested through diet?

Thanks for any help you can offer!

Steve Freides

Forum Administrator
Staff member
Senior Certified Instructor
@Physical Culture, nice to see you here again, sir.

I think a lot depends on the individual, their current body composition, and both their overall training experience and their current training. I don't think this is one size fits all. E.g., overweight people new to training can probably lose fat and gain muscle at the same time. To date, most experienced trainees with serious hypertrophy goals generally don't expect that - they expect to gain muscle and fat in caloric surplus, and to lose both when in deficit, and hope that their training is the "magic sauce" that lets them end up more muscular and less fat after a cycle of each.

This is discussed in Q&D - a recommended read if you haven't already read it. Examples are given of two different protocols, one of which seemed to foster hypertrophy while the other didn't.


captain slow

Double-Digit Post Count
"His idea is to have a positive energy balance on training days, to grow muscle, and a negative energy balance on non-training days, to lose fat."

In the beginning, a newbie can make progress by taking in a decent calorie surplus every day, muscular growth and strength development can be quick and excess calories get "sucked up" by the tissues rapidly. As you get closer to your potential your progress slows and some kind of calorie cycling makes sense.

Generally, look at weekly calories and work from there but I wouldn't think of it in terms of a positive and negatives balance. Say your original sedentary BMR required 2,500 kCal/day, now, after a year of hard exercise your BMR maybe 3,500 kCal/day (to accommodate exertions of hard training and extra mass), your cycling could be something like 3,900 kCal/ day on training days and 3,200 kCal/ day on non-training days. You are still way above your sedentary daily requirement of 2,500 kCals.

"It's often said that a calorie surplus is required for hypertrophy. Is this true?"

I would say yes, but any bodyfat metabolised would count into that surplus otherwise you wouldn't drop fat when you increase activity and maintain calorie intake. How much BF is being used would be difficult to measure except by measuring ingested calories and tracking bodyweight. Aim for a reasonable BF decrease per week/month otherwise you'll eat into muscle tissue.


Quadruple-Digit Post Count
Interesting questions. I have no answers, however.

Seems like he might have been following leangains by Martin Berkhan:
MB said:
The Leangains protocol consists of two phases; 16 hours of fasting, followed by 8 hours of feeding. During this period, three meals are usually eaten. Depending on the day, the composition of those meals varies; on workout days, carbs are prioritized before fat, while on rest days fat intake is higher. Protein remains fairly high on all days.
Sure-Fire Fat Loss | Leangains
The Leangains Guide | Leangains

I find this method interesting but haven't bothered to try it for myself so far.


Quadruple-Digit Post Count
Worth reading and listening to doc Andy Galpin. He's a muscle fibre researcher and expert.
He confesses to only being able to scratch the surface of muscle metabolism, there's a lot of 'don't knows'. Of course, many approaches work but it's not a one size fits all, it seems. His take: adaptation v recovery. If you seek to optimise recovery it prohibits adaptation. Example: muscle hypertrophy session with a cold shower as recovery.....sort of thing. Conflicting physiological processes.
At the risk of paraphrasing badly check out his stuff first hand.

Physical Culture

More than 500 posts
Thanks, all! I have Q&D, and I'm using it along with clean and press ladders for my off-season training for kettlebell half marathon. My goals are to add some muscle and strength, as well as increase mitochondrial density. In the spring, My goal is 215 clean and jerks in 30 minutes with a 32k kettlebell. I'm experimenting with IF- thus the questions about hypertrophy, calories, and time. I appreciate the perspectives!


More than 300 posts
Studies have reliably demonstrated hypertrophy during calorie deficit in untrained to elite level athletes. The human can certainly build muscle and lose fat at the same time although better results can be expected focussing on one or the other. Maintaining adequate protein is probably more the issue for building muscle as calories from body fat assumedly replace for that purpose at least some of the deficit in ingested calories

Midlife Beast

Double-Digit Post Count
Jeff Nippard, one of those youtube bodybuilders, has a recent video that talks about hypertrophy while on a deficit. Seems to be more possible than most people think.

Video seems to be promotion for his book, but some interesting studies are cited and I think he does a good presentation overall.



Quadruple-Digit Post Count
An overview to help answer the question:

Is an Energy Surplus Required to Maximize Skeletal Muscle Hypertrophy Associated With Resistance Training

As already mentioned, its multi factorial with goals and sport at play with soooooo many variables.
It is possible to gain muscle lose fat in calorie deficit but it depends on the variables.
Overall, it seems, on balance a mild surplus is recommended and evaluated. 500 cal. Depends on your energy needs.
If you train and do sweet fa for the rest of the day or have a manual job or stressed or very lean/fat it'll be different to that of an elite athlete or lab experimented muscle biopsy.
Top Bottom