Is There A Maximum Fat Loss Limit ?

I know the body has a limit on how quickly it can build muscle, set by hormones, genetics, how much muscle you have built etc Eating and training more won’t make your body construct muscle any faster, you’ll just get fatter.

But what about fat loss ?

Does the body put a limit on how fast it can consume its fat stores for energy ?

If there is a limit and what is it controlled by ?

What determines when the body starts breaking down muscle ? Some say more than 2lb per week and your probably losing muscle but you cant put everyone in one box like that.

I have been cutting hard with about 9000cal/week deficit the past month and have lost about 12lb (from 14%bf so no in the obese category) and I doubt much of it came from muscle as I haven’t lost any strength or reps.

I know nutrient partitioning and insulin sensitivity comes into play, but I doubt I have those advantages coming from a family where my dad and grandad have type 2 diabetes and having a set point BF% around 13-14%.

I would love to know the science of it all.

check out Lyle McDonald’s stuff on fat loss for more science than you could ever possibly need. It gets pretty heavy but it’s interesting stuff

Continued good thyroid production depends on sufficient carb and protein intake, and cutting calories too low will impair this.

As opinion, getting more caloric deficit with more exercise doesn’t impair metabolism, at least if it’s done where there isn’t an excessive amount of excessively intense work.

As an example of the extreme, Ranuph Fiennes and Mike Stroud dropped about 20 kilos, which I remember as being nearly all fat in the case of Fiennes, in crossing Antartica in 90 days, dragging heavy sleds the whole way. That’s about 3.4 lb of fat loss per week.

With pharmacological assistance, 3 lb per week of fat loss is commonly obtainable.

I don’t really understand how it could happen but there was a 4 week period where I dropped about 12 lb of fat completely unintentionally with Anaconda and MAG-10 and some rather extreme weight training (I was doing my own 5-3-1 derived program but hitting heavy lower body exercises 3x/week not 1x, doing 3 such exercises each time not 1, so 9 times the volume Wendler would have wanted, and doing them as 8-6-4 not 5-3-1. My knees gave out, otherwise it was a tremendous success.) No pharmacological assistance either.

I think about 3 lb per week is the reasonable practical limit on a sustained basis. It’s possible though on a given day to exceed that rate.

For short periods it’s possibly to lose at very fast rates. The problem is that fairly soon your body tries to compensate for your new reduced food supply by turning down your metabolism and shutting off expensive processes like muscle protein synthesis. For example, low calories tends to increase production of rT3 (up to 58% with total fasting or lesser levels when on a reduced calorie diet). If this weren’t such a big concern the v-diet wouldn’t have such strong warnings about not continuing it for long periods.