How much fat can you pull from your fat stores for your energy needs?


Also, holy crap I was dying. :rofl::rofl:

Dr. Fung dropping the f bomb like nobody’s buisness

(Regina) #6

Yeah, what’s up with that? Makes him look really unprofessional. He might have good things to say, but why the necessity for profanity?

(Regina) #7

Katie, you are overthinking this. I am at maintenance at 16 weeks. Your body needs nourishment. Thirteen pounds is nothing. Don’t put your body at risk for that. TMAD is sufficient.

(Katie ) #8

My maths is shit so I hope I get this right

155 pounds total with 30% body fat = 46 pounds * 31 = 1426

I am not sure what this is supposed to tell me, this means I can supplement ALL of my fat via my stored body fat?

(Katie ) #9

Thanks for the link :slight_smile:

(karen) #10

… it really just means that’s the absolute maximum amount of body fat your body can access in a day. “How much of my energy can be drawn from my fat stores” - yes, if you’re actually burning 1240, theoretically all of it. If you fast, you should be able to access all the calories you need from your fat, and not start breaking down muscle - which could happen if your fat-burning limit can’t keep up with your calorie needs.

This number doesn’t really tell you much about what you need to eat to cover your exercising needs, keep from going into a metabolic slowdown, promote fat loss or stay in ketosis, sorry, it’s just one piece of info. Good luck, and congrats on your success so far!

(Katie ) #11

Thanks for explaining it, I understand it now!


I found I liked him all the more for it, but I swear like a sailor.

I find the stored fat access to be an interesting idea, but I agree there are too many variables to really do much with it. Except once you get past a certain low body fat % you are going to want to eat some calories.

(bulkbiker) #13

Possibly because he is quite passionate about what he has to say… also he’s human…
Best not to judge the message by how it is delivered?


@kib, @safi
I would take the Alpert calculation with a grain of salt. It’s based on starvation - not fasting - and on folks who are not fat-adapted. This is not to say that there’s no limit to how much fat we can access during a fast; maybe there is, but it’s probably highly variable. I wouldn’t use that study as a basis if you’re fat-adapted and fasting rather calorie-restricting (unless I’m getting my studies mixed up, this is on long-term calorie restriction, which as we all know is a disaster for energy and metabolism).
Based on the calculation I would be a wreck on a water fast, but I’ve often done hot yoga classes on top of a full day of work with no problems on days 3 or 4 of an EF.


Here’s the starvation portion of the experiment that is the basis for Alpert’s calculation:

Semi-Starvation Period (24 weeks): during the 6-month semi-starvation period, each subject’s dietary intake was cut to approximately 1,560 kilocalories per day. Their meals were composed of foods that were expected to typify the diets of people in Europe during the latter stages of the war: potatoes, rutabagas, turnips, bread and macaroni._

I’d be very curious to see a similar calculation based on fat-adapted fasters, but I’m not holding my breath on that study :slight_smile:

(Raj Seth) #16

Do not use the caloric deficit model. Use the maintain model. Then, eat when hungry, eat till full. Don’t eat when not hungry…
The lower insulin level will allow your body to reset its set point and the body will down regulate the fat stores to where it wants. A few IF, ADF etc is what you need. But eat what your body wants (minus carbs)

(Katie ) #17

I was under the impression that once adapted to switch to a deficit?
I cant even meet either calories on Omad whether its 1200 or 1500.
I want to start working out again, I am just trying to work out how to maximize the last of my weightloss so I can start getting ripped :joy:

(Katie ) #18

Thanks for explaining. I’ve never heard of this study so its interesting.


There is a fair bit on youtube about whether you should cut or bulk depending on where you are in terms of bodyfat% & how long you’ve been training. You’ll have to trawl through some dudebros but you might find a trainer you like. Are you basing your 30% bodyfat on a Dexa or is it more of a guess - I ask because having seen your pictures (well done by the way :smile: ) I’d have pegged you a bit lower.

(Katie ) #20

I have an excel document that I input my measurements of weight, chest, waist, thighs, calves, hips, wrist and forearm and it calculates my estimated lean body weight, body fat weight, percentage and BMI

So when I input my current weight at 70.5 and I get ;

55.68 lean body weight
14.82 estimated body fat
21% estimated body fat percentage and
24.98 estimated BMI


At those numbers, if you’re going to start lifting, then I would eat at least at maintenance calories so you get the most out of your ‘newbie gains’. That’s not to say I wouldn’t OMAD here & there (I do it 3 days a week & am building muscle) but I certainly wouldn’t go with a consistent deficit if I were hoping to build muscle.

(Katie ) #22

This is what I am wondering.
I’m struggling because I fear I am not getting enough food into my OMAD hour 3-4pm.
I’ve been running at a deficit for many many weeks now, and I fear I am hurting myself rather than helping.

Obviously I can’t get any gains on such a big deficit, I think I’m only eating up to 1000 calories a day consistently for upwards for 5 weeks now so I’m freaking out a bit.


Eat two meals a day for a while & see how you go. I eat OMAD 3 days a week because I really like how I feel when I do but I know I don’t get enough calories in for my goals so I make up for the deficit on other days. I figure it keeps the body guessing too :smile:

(Katie ) #24

That’s what I thought, and I might do that for the next few days just to shake it up.
I have no problem with my commitment or motivation.