Determining the Maximum Dietary Deficit for Fat Loss
10-29-2006 02:47 PM
Determining the Maximum Dietary Deficit for Fat Loss
Determining the Maximum Dietary Deficit for Fat Loss
by Lyle McDonald
A long-standing question in my mind has been, ďWhat is the optimal (or maximal) deficit for a fat loss diet?Ē Yes, I know Iím not the first to address the issue but Iíve always wondered if we couldnít figure out exactly what an optimal deficit might be on a diet, rather than relying on annoying trial and error.
Iím sure readers are familiar with previous approaches but letís run through them quickly. The simplest (read: totally retarded) method of setting calories on a diet is to give everyone some fixed amount. Usually women get 1200, men get 1500. How such an intake can magically be correct regardless of bodyweight or activity, I have no idea. But apparently a 300 lb man and a 150 lb man should both eat an identical amount and that amount is 1500 calories/day when they diet. Amazingly, in 2006, that kind of moronic stuff is still out there.
The second approach is along the lines of, ďTo lose one pound of fat per week, eat 500 calories/day less than your maintenance; to lose 2 pounds, eat 1000 calories less per day.Ē Simple math, although not entirely correct for a variety of reasons I donít want to get into. I addressed problems with both approaches in the big Ketogenic Diet book.
In Bodyopus, Dan Duchaine (who was writing for lean folks, remember) recommended a maximum deficit of 20% below maintenance. Better, as this at least scales the deficit relative to maintenance. A big ass guy with a 4000 calorie maintenance gets a larger deficit (800 cal/day) than a small female with a 1700 calorie maintenance (340 cal/day). Of course, weekly fat/weight loss will be significantly different for the two, which seems to pass the reality check. Bigger males do lose more fat than smaller females. I regularly advocate this approach.
In the Ketogenic Diet book, I suggested setting a deficit based on current total bodyweight, since most people have trouble figuring out their true maintenance intake. Assuming an average maintenance intake of 14-16 cal/lb (you can use 15 cal/lb and split the middle), a 20% deficit yields ~11-13 cal/lb (and 10-12 cal/lb for dieting has been around in the bodybuilding world for at least a decade), which will then have to be adjusted based on real world results. Some people, for example, with low daily activity and ****ty genetics, may have to go to 8 cal/lb AND do aerobics to lose fat effectively. Back when I was lifting twice/week and doing ****all else activity, I had to do that. Now that Iím training 16-20 hours/week, I get to eat more when I diet. Hooray. In the two new books (The Rapid Fat Loss Handbook and A Guide to Flexible Dieting (you should BUY THEM NOW), I offer my personal scheme for adjusting intake based on whatís happening to bodyweight and strength levels in the gym.
Now, empirically and based on research, itís well established thatÖ
a. fatter individuals lose more fat and less lean body mass (LBM) than leaner individuals; and
b. bigger individuals lose weight more quickly
By corollary, smaller/leaner individuals not only lose total weight/fat at a slower rate, they lose a greater proportion of LBM. The whole issue of calorie partitioning has been discussed to death in my various books, especially The Ultimate Diet 2.0.
Itís why those fat asses on ďThe Biggest LoserĒ can drop 8-10 lbs. a week, well at least for the first week (and some of that is certainly water, glycogen and clearing the **** out of their bowels), and someone at 12% bodyfat may struggle to drop one pound per week without sacrificing muscle.
And anybody who read the Rapid Fat Loss book notes that I sort of worked the above into the schema: based on starting bodyfat, fatter individuals end up with a larger deficit than leaner individuals. Leaner folks ended up maybe 40% below maintenance but fatter folks might have been as much as 75% below maintenance. But it was a rough back of the hand kind of calculation; it was more that I wanted protein intake set at a certain level and daily caloric intake sort of fell out of that. As it turns out, the feedback Iíve received tells me I was at least in the right ballpark: leaner folks arenít losing LBM (as long as they set it up correctly) and fatter folks are dropping fat like crazy.
Now, some work on fasting had suggested a maximal rate of fat oxidation (youíd expect this value to be largest during total fasting, but the numbers never quite worked out how I wanted to express them. So I gave up on the question for a bit.
The basic question in my mind, and the one Iím going to address here is, ďBased on an individualsí current bodyfat/bodyweight level, do we know what their maximum rate of weekly fat loss can or will be?Ē Phrased differently, whatís the maximum deficit that they can run and spare lean body mass?
So imagine my surprise when this little theoretical paper (note the journal title) showed up on my Pubcrawler last year (1). Titled, ďA limit on the energy transfer rate from the human fat store in hypophagiaĒ, it examined (from a somewhat simplified and theoretical way) exactly the question I gave above: what is the maximum rate at which the body can derive energy from fat stores to cover a diet induced deficit while sparing lean body mass.
Itís a nasty little paper, filled primarily with equations, explanations of those equations and some more equations to boot. Headache inducing to be sure. Iíll spare you the details. Based on a somewhat simplified analysis of what data exists (including the seminal Minnesota semi-starvation experiment), they conclude that the maximal rate at which fat stores can provide energy to the body is 290 +- 25 kj/kg which is approximately 31 kcal/lb of fat per day.
So, if you are carrying a mere 10 lbs. of fat, you can sustain a 310 cal/day deficit.
20 lbs. = 620 calories.
30 lbs. = 930 calories
You get the idea and this is not difficult math. Multiply your total fat mass in pounds by 31, thatís how much of a caloric deficit that fat mass can support on a daily basis.
One quick note: the above values are for dieting only and one of the simplifying assumptions in the paper was relatively Ďnormal/moderateí activity levels. The paper mentions specifically that the values above might be varied through pharmaceutical means (which target the rate limiting steps of fat energy transfer), or through high levels of activity. It even mentions bodybuilders specifically as a group that might exceed this value with a lot of training. For now, Iíll just focus on the diet end, Iíll come back to drugs and exercise afterwards.
So, the basic assertion of the paper is that, so long as the net daily deficit does not exceed what your fat stores can provide, you should spare lean body mass. And based on the small amount of research that they found, this seemed to be generally true (many studies find an initial rapid LBM loss but this is most likely glycogen and water and stuff, not muscle mass). By extension, if your daily caloric deficit exceeds the above, your body will have to mobilize LBM to cover the difference. So letís look at an example.
Say we have a 180 lb male at 15% bodyfat. He has 27 lbs. of fat, and his maintenance calorie intake is 15 cal/lb or 2700 calories. With 27 lbs. of fat, he should be able to sustain a caloric deficit, from diet alone, of 27 lbs. fat * 31 cal/lb = 837 calories/day. So he could reduce his calories to 1863 (ha! 10 cal/lb) and shouldnít lose any LBM at that level of intake. He should get a weekly fat loss of just over 1.5 lbs./week.
If the same 180 lb guy was at 10% bodyfat, only 18 lbs. of fat, he could only sustain a 558 calorie/day deficit (2150 cal/day or 12 cal/lb), heís down to 1 pound per week. By the time heís at 8%, heís down to 14.5 lbs. of fat and a total deficit of 446 calories/day and about 2/3 a pound of fat loss/week. Oh yeah, if he were a fat **** at 30% bodyfat, thatís 54 lbs. of fat, he could sustain a deficit of over 1500 cal/day and lose over 3 pounds per week of pure lard; of course heíd only be eating 1300 cal/day. Again, the above all seem to roughly pass the reality check in terms of what we see in human dieters.
Now, one implication of the above is that, as a diet proceeds and your fat stores shrink, your net deficit has to decrease. Ok, step back, take a breath and read that again. More importantly, note my use of the word Ďnetí in the first sentence of that paragraph.
Now itís going to get confusing.
At first glance, the above seems to be indicating that, as you get leaner, youíll need to raise calories to compensate, so that the deficit isnít as extreme. But thatís incorrect; it is saying that fat loss will need to slow (because the net deficit you can sustain will be smaller). By Ďnetí deficit, I mean the difference between your current maintenance requirements and your intake. This is important because, as you diet, your maintenance requirements go down due to the loss of bodymass along with the adaptive component of metabolic rate (due to insulin, leptin, ghrelin, peptide YY, etc). Letís simplify this by looking at the math.
Our 180 lb man at 15% starts his diet. He has 27 lbs. of fat and can sustain a maximum deficit of 27 lbs. * 31 cal/lb = 837 calories. Assuming a maintenance of 15 cal/lb (2700), his starting calorie level will be 2700 cal - 837 calories = 1863 calories/day. Heíll be losing around 1.5 lb fat/week.
So now we check in 8 weeks later, heís down 12 lbs., almost purely of fat (weíll ignore any small LBM losses). His new numbers are 168 lbs. with 15 lbs. of fat = 9% bodyfat. Maximal sustainable deficit = 15 * 31 = 465 cal
Assuming his maintenance is still 15 cal/lb (not automatically a safe assumption), his maintenance requirements should now be 2520 calories. But the adaptive part of metabolic rate reduction has probably dropped him a good 10% below that. So letís say his maintenance is 2250 cal/day or so. 2250 cal/day - 465 calories = 1785 calories. So, not much of a reduction from his previous 1863 calorie/day diet. Basically, the drop in his maintenance levels over the course of 8 weeks offsets the fact that he canít sustain as much of a deficit and is now leaner. Of course, his fat loss has also slowed to just under a pound/week.
Now four weeks later, heís dropped about 4 more pounds of fat. His new numbers are
164 lbs. with 11 lb of fat = 6.7% bodyfat. Maximal sustainable deficit = 11 * 31 = 341 cal
His maintenance will have dropped further, letís say 14 cal/lb (peopleís daily activity tends to go down due to the hormonal changes from extreme dieting) and a 15% adaptive reduction which brings him to 1951 calories/day. Reduce by 341 to get 1610 calories/day. He will need to reduce daily calories by a couple of hundred (from 1785/day to 1610/day) to achieve the maximum deficit but his fat loss will be down to 2/3rds pound per week.
Ok, step back for a second: the above calculations arenít meant to be the holy word of god, there are a lot of estimates upon estimates being made, especially my guesses as to the changes in maintenance level and how big of an impact the adaptive component is having. The adaptive component is a big question mark with not enough data for my liking. Tracking morning body temperature gives a rough guideline: for every 1 degree drop in morning temperature below 97.8 degrees, your metabolism is suppressed by about 10%. This was more to illustrate what I meant by Ďnet deficití with changes in both fat mass and maintenance requirements.
But, again, the above seems to scale roughly with reality. As people get leaner and leaner, fat loss slows drastically. To keep it moving, they have to either cut calories further or increase activity, both can cause muscle loss. Every bodybuilder who has had to move to 2 hours/day of aerobics to keep the fat coming off knows what Iím talking about. Drugs become more and more attractive as the myriad other systems start to fight back against you as well (on which note: will someone please get the folks working on intranasal leptin to hurry it up).
Drugs and exercise
As mentioned above, the paper Iím basing all of this nonsense on was looking at non-exercising dieting or fasting men, not folks who were training or taking drugs. And it mentioned specifically that both of those could potentially increase the maximum rate of fat mobilization value (above 31 cal/lb) without sacrificing lean body mass. Certainly, once again, this idea passes the reality check. Even the addition of the ephedrine/caffeine stack elevates fat loss while sparing muscle mass. Clenbuterol is more potent, GH is great and DNP is like ****ing magic.
Clearly, exercise also has an impact. Even back in Bodyopus, Dan mentioned that only part of the total deficit (he used 20%) should come from diet, the other part should come from increased activity. This usually means aerobics, but some prefer to use high rep/short rest period weight training or interval training and there is some logic to picking one of the latter options. He suggested that men do better with 15% calorie deficit and 5% aerobics and women at 10% apiece. Given the issues women have with lower bodyfat blood flow, and that aerobic activity can overcome some of the limitations that make lower bodyfat so stubborn, that makes a lot of sense. As well, women (because of their lower maintenance requirements), end up eating a tiny amount of food if they cut too much out of their diet. Increasing their net daily deficit via activity allows them to eat more and not starve to death on a daily basis. Iíve been working on the stubborn bodyfat issue for years now; my next book outlines not only the problem but multiple solutions to that problem.
In this article, Iíve been able to give dieters a starting point for the maximum sustainable deficit which can come from calorie restriction. To summarize: simply determine how many pounds of fat youíre carrying. Then multiply that value by 31 calories. Thatís how much you can potentially decrease your daily food intake. If you want to try to increase fat loss, any further increase in the deficit should either come from increased activity or compounds that either increase the mobilization or burning of fatty acids for fuel. As well, as you get leaner/lighter, you will need to periodically recalculate your daily calories to take into account your diminishing fat mass and decreased maintenance requirements due to both decreased bodymass and the adaptive component of metabolic rate. An argument can also be made for saving increases in activity for later in the diet when your diet deficit has to be lower.
Please keep in mind, however, all of these theoretical calculations sort of pale to real world results. If youíre losing strength in the weight room like crazy, your deficit is too big regardless of what the math works out too, increase them until you stop hemorrhaging strength (and probably muscle). And even if you have to trial and error it a bit, the above should at least give you a starting point.
1. Alpert SS. A limit on the energy transfer rate from the human fat store in hypophagia. J Theor Biol. 2005 Mar 7;233(1):1-13.
10-29-2006 11:25 PM
That looks good on paper, but how are they determining the maintence cals?
E-Pharm Nutrition Representative
10-30-2006 12:15 AM
sorry if i sound stupid, but isn't the maintenance cals calculated based on your age, weight and daily activity levels?
10-30-2006 08:16 AM
Thats a good article.
I think most people find there way to internet fitness boards because they are trying to lose weight. Not all ofcourse, there are lots of skinny guys looking for pharmaceutical help. But weight loss seems to be dominant.
So if your not a hardcore bodybuilder, why not throw out the issue of losing LBM altgoether until you lose the fat?
I mean we are genetically predisposed to carry a certain amount of LBM under natural circumstances. So a rebound in LBM would be easy if you started from a smaller and leaner physique. The results from such a rebound would be amazing.
So obese guys should stop trying to save muscle and get rid of the fat first. You can start at the maximum deficit as written in this article with a slow walking exercise regimen and an easy lifting session of 1 body part per day\1 heavy set to promote strength retention.
Then as weight decreases and fat loss declines, slowly increase the exercise to compliment the "net deficit" and you are on your way to a lean body with amazing results.
Instead of this "dont cut too many calories or you will lose your natural muscle" mentality. And this "safe" mentality.
I mean fat burned is calories consumed so its not like your totally starving yourself. Cut the calories and lose the fat. Stop worrying about muscle and let thefat do its job. Which is provide energy for a starving human.
Then when you refeed you will regain natural LBM rather quickly. And then some with increased carbs and protien! Plus you will be able to monitor your fat gain under an eating situation, instead of fighting LBM LOSS under a tough and slow dieting nightmare that we all cycle through over the years while gaining a couple pounds of FAT every year to boot.
Get rid of the fat first, the natural LBM will return whenever you want it back, just carb up! But dont start feeding the muscles until that fat is good and gone!
Ofcourse bodybuilders are already above the genetic LBM so they stand to lose the hardwork put in. But fatties need to get the fat under control and the muscle will come back quickly!
Nice enlightening article.!
I weigh 240 at 35 yrs old and it is the fattest ever in my life.
I will take some pics and put this theory to the test right here starting today. Thanks for the motivation. I ll post a log with pics and results.
Last edited by Billy the kid; 10-30-2006 at 08:50 AM.
11-06-2006 10:48 AM
yea. but its not always 100% accurate to determine what the scale considers "active" and what you consider active. theres minor discrepancies all over them,
Originally Posted by ZoMbSta
so if you determine your weight, your fat % and then the amount of fat on your body, you calculate the amount of cals you eat a day to maintain this fat lbs, then dont eat that amount of calories from your maintenance.
11-10-2006 09:52 AM
ok....thanks for the heads-up..but let me get this straight...
say my daily maintenance is 2400 cals...that means i need to eat up till 1900cals assuming the max deficiency i can hold is 500 cals? and if i happen to workout and do sports and other activities and i end up havin a total of 3000 cals burned or more for the day... do i need to up my cals intake to 2500 cals?
in another words...do i need to up my cals if i up my activites or will my cals deficit be determined by my daily maintenance and hence my daily cal intake is constant until my weight drop further?
11-10-2006 05:23 PM
Does it matter on the type of calories as well or are calories just calories?
11-10-2006 06:15 PM
Originally Posted by dlew308
get 100% of your calories from peanut butter and cheese doodles and see what happens.
11-10-2006 06:19 PM
I know eating PB & cheese doodles aren't a nurtritious way of going about it, I just meant it in a different sense. Let's say one follows the calorie cutting as mentioned above, what should the % of fat/protein/carbs be?
Originally Posted by thesinner
11-10-2006 10:19 PM
this kind of qns has been answered over and over again..and many of the ppl here has done logs on it...since you r a newbie here..a word of advice...try the search button...
Originally Posted by dlew308
11-11-2006 02:52 AM
50% carbs, 30% protein, 20% fat OR 40-40-20 is a good starting point. Get low GI carbs such as broccoli-oats-brown rice, good fats like fish oil, extra virgen olive oil (EVOO), chicken, turkey, lean beef, egg whites.
Originally Posted by dlew308
For cutting, I go with 10-13 calories per pound of bodyweight. For bulking, I go with 20-25 calories per pound of bodyweight. I do incorporate cardio while bulking too. This is what works for me but I think it can help you out with your plan of attack.
11-13-2006 08:53 AM
can anybody help me with this qns?
Originally Posted by ZoMbSta
11-13-2006 09:29 AM
Maintenance is a state in which you neither lose or gain weight. This includes activity level.
If you eat X calories with Y amount of activity and maintain weight you are at maintenance. If you increase activity you create a deficit causing potential weight loss. If you decrease calories you create a deficit causing potential weight loss. A combination of both increased deficit and increased activity will cause potential for weight loss. Most opt for a slight decrease in calories and a slight increase in activity. The degree at which you attach either is dependent upon you goals and ability and willingness for for increased activity.
11-13-2006 11:08 AM
thanks alot..that means if i wanna hav a 500cals deficit from BMR to induce fat loss...in order to induce more fat loss is by increasing my activities which i'm doing on a daily basis? and that means i don't hav to compensate my increased activities with more cals?
Originally Posted by B5150
11-13-2006 11:10 AM
Deficit = Energy in < energy out
Surplus = Energy in > energy out
11-13-2006 11:18 AM
haha..i know deficit and surplus...what i was tryin to ask was actually if there is a need to compensate with increased cals to maintain overall deficit of 500 cals or can i eat 500 cals less than BMR and then increased my activities to induce more fatloss in accordance to the article above by lyle mcdonald...
pardon me for testing your patience here...but i'm quite worried abt losing large amt of LBM along with fatloss..i know losing abit in inevitable but i am tryin to reduce the amt lost..
11-13-2006 11:43 AM
If you want exactly 500 cals deficit then yes. There is much debate over what degree deficit will induce catabolism. Lyle tends to become anal about matters and rightly so...to a point.
Depending upon your phenotype it can make no difference or a huge difference. If you are an ecto and are getting a lot of your deficit from cardio you potentiate catabolism if you are disposed to it. As an endo I can run my ass off and retain LBM in a huge deficit...but also retain fat as well.
This is where nutrient timing and all sorts of other tricks of dieting can come into play. Ultimately we all will lose some LBM when we diet. Your strict adherence to specifics is dependent upon your determination and discipline.
11-13-2006 09:24 PM
If you're more active than your maintenance calories would actually be hire. His 15cal/lb was just a guideline. For example.
Originally Posted by ZoMbSta
A 200lb man has 15% bodyfat. That's 30 lbs of fat * 31cal/lb = 930 calories as a deficit. That means you'll take the total amount of calories burned in a day, let's say 3000 and subtract 930, so you'll only be taking in 2070 calories.With these example numbers that a 30% calorie deficit. I think thats right. If not someone please correct me.
11-13-2006 11:31 PM
Ok. I just went and pluged in my current stats:
BF% = ~30%
Weight = 215
BF = 64.5 lbs
and I figured out week by week how much weight I would lose. I recalculated my figures every week. FYI, I didn't use 100% of the deficit calories for every week, just to give myself a few lbs. But after 8 weeks this is what my new stats would be, not taking into account LBM loss or very little LBM loss:
BF% = 22%
Weight = 192.63 lbs
BF = 42.13 lbs
This would be quite a big change for eight weeks, but I'm ready for a big change. I'm tired of the way I look and feel. Tomorrow I will start planning out my meal plans. Wish me luck!
BTW, I have read a lot of other diet stuff on the internet from other bodybuilding and diet websites.
11-19-2006 05:33 PM
Does anyone think that it might be too big of a deficit though? Everything else I've been reading says that its prolly too much. Thanks.
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