October 10, 2023

Can your metabolic rate increase enough to lose 3lbs of fat in one day?

This is an expansion of a sub-topic I briefly touched on in my last post Runaway Metabolism During Peak Week Carb Load.  That article was focused mostly on the common issue of struggling to fill out during a carb load, the days leading up to a show.  But there was one part of the article where I briefly mentioned a reddit thread about a competitor who had been maintaining her stage weight/level of leanness for the few weeks leading up to her show, when suddenly she saw a 3lbs drop on the scale, overnight.  You would think most coaches (and even most competitors/athletes in general) would know that this would be from a drop in water weight, maybe pooping a little better that morning, etc.  But, in true bodybuilding industry form, everyone in the thread decided it was 3lbs of fat loss…in one day.  Not water weight and/or poop…but pure fat loss.  It was said that the girl’s metabolic rate ‘kicked up’, which according to several people commenting on the thread, happens often with drug-using competitors.

I kept waiting for someone to bring up the obvious issues with this premise, since I never want to publicly criticize individuals…I’m knowledgeable enough to be able to just speak on the issues, rather than going after people.  And if this were an isolated incident, I wouldn’t be writing this.  But unfortunately this inability of fitness industry folk to recognize the difference between water and fat, or really have any clue about human metabolism (how much it can drop, how much it can up-regulate, how quickly it can do these things with vs without drugs, etc), is a regular occurrence, so here we are talking about it.


Technically this post discusses ideas and events, so I’m being ‘Graverage’ right now


So let’s look at this claim.

1lb of fat is 3500 calories.  So 3lbs of fat loss in 1 day would require a caloric deficit of 10500 calories.  And not everything you eat gets digested, and not everything you’ll burn is fat, and the expenditure (calories out) side of the equation is not static. So really you’ll need to do more than just ingest 10500 fewer calories or do 10500 calories more exercise, before you’ll see 3lbs of pure fat loss.  But we’ll go with 10500 to keep it simple.

Most of your total daily energy expenditure (TDEE) comes from non exercise activity, exercise activity, and basal/resting metabolism. Thermic effect of food is only about 10% of the calories that are in your food…so it doesn’t contribute much to TDEE. So we’ll look at the first 3 components I listed.

Can you burn 3lbs of fat in one day by increasing your basal metabolic rate (BMR)?

You could possibly increase your BMR enough to be on pace for 3lbs of fat loss in one day. It would require uncoupling of oxidative phosphorylation to a degree than can only be achieved via administration of a HIGHLY toxic/deadly drug called DNP (2,4-Dinitrophenol).

However, the dosage you’d need to take would GREATLY exceed the highest dosage (in a single day) we have on record, in all of the deaths caused by this drug in the past 100 years. DNP increases your BMR by about 11% per 100mg. So if your BMR is 1200 calories/day (about right for a dieted down bikini girl), and you need to burn 10500 calories, you’d be looking at about 8-9g of DNP. The highest lethal dose on record is around 4.5g, in one day. This led to a body temperature of around 106 degrees Fahrenheit, and death about 9 hours after administration.

Think you can get there with DNP + increased activity? Uhh..no..even with a ‘normal’ dose of DNP, you’re not doing anything but sitting in an air conditioned room. Even the lunatics who still recommend this drug will tell you not to try to train on anything more than about 100-200mg. 8-9g is 40-90 times this amount!

And the cause of death is strictly a result of the hyperthermia, tachycardia, diaphoresis and tachypnoea induced by the drastic elevation of metabolic rate.  So even if the body were somehow willing to elevate BMR this drastically without DNP, you’d still die from it.  There’s no antidote at all for DNP, or for anything that could lead to this type of elevation of BMR.  You. Will. Die.


2,4-Dinitrophenol (DNP): A Weight Loss Agent with Significant Acute Toxicity and Risk of Death

SexAgeType of exposureDoseTime to deathMaximum temperatureYear [reference]
MNROccupationalN/A—occupational14 h 30 min40.5°C (104.9°F)1916 []
MNROccupationalN/A—occupationalUnknownUnknown1918 []
36 workersN/AOccupationalN/A—occupationalUnknown43°C (109.4°F)1919 []
M Weight loss2.5–5 g10 h 10 min> 43°C (>110°F)1933 []
F46Weight loss300 mg over 6 weeksN/A40.4°C (104.8°F)1934 []
F31Weight loss6.06 g in 4 days16 days after start of trial38.9°C (102°F)1934 []
F25Weight loss2.88 g over 5 days7 days after first dose38.9°C (102°F)1934 []
FNRWeight loss∼10 g over 6 weeks5 days after admission41°C (105.8°F)1934 []
M37Weight loss9 g over 7 days11 h40.9°C (105.7°F)1934 []
F13Weight loss5.4 g over 46 days20 h after admission40.9°C (105.6°F)1936 []
F21Weight loss4.5 g9 h 10 min41.1°C (106°F)1936 []
MNROverdoseUnknownApprox. 12 hUnknown1953 []
M61AccidentalUnknown24 hUnknown1960 []
F17Weight lossUnknown? 28 h38.5°C (101.4°F)2002 []
M22Weight loss2.4 g over 4 days17 h after last dose38.9°C (102°F)2004 []
F17Overdose2.3–2.88 g10 h> 40°C (>104°F)2005 []
M24BodybuildingUnknownUnknown40.8°C(105.5°F)2005 []
F17BodybuildingUnknown3 h after presentation39.4°C (103°F)2006 []
M28BodybuildingUnknown50 min after presentation41.1°C (106°F)2006 []
M30BodybuildingUnknownUnknownUnknown2007 []
F27Weight lossUnknown over 1 week8 h after presentation38°C (100.4°F)2009 []
M46Overdose2.8 g21 h37.8°C (100.0°F)2010 []
MNROverdose2.8 g15 h39.5°C (103.1°F)2010 []
F49OccupationalN/A—cutaneous15 h38.9°C (102°F)2010 []
M41OccupationalN/A—cutaneous9 h38.5°C (101.3°F)2010 []

NR (not recorded) ;


Can you burn 3lbs of fat in one day by non exercise activity (NEAT)?

No. Take all the stimulants you want, you’re not burning anywhere close to 10k calories via NEAT. 2k maybe…10k, not possible. The claims I’m responding to were competitors towards the end of their prep, so energy levels would be way too low even if this were possible.

Nervous system output/expenditure might kick up a little bit just from anxiety about your show, and you may be a little more active with all the tanning/hair appointments, walking through the airport (if traveling for the show), etc. And that might cause you to burn through your glycogen a bit, while trying to carb load. But no way you’re getting anywhere close to 10500 calories burned by this mechanism.

There’s also a limit on how much fat mass can be lost in one day, before your body starts burning through fat free mass (muscle, connective tissue, organs, etc) as shown in this study.  It’s (290±25) kJ/kg d, which in English is 70 calories per 2.2 lbs of bodyweight per day.  And in ‘Merican, that’s 32 calories per lb of bodyweight per day.  The competitor in question was probably around 125lbs (give or take), so about 4k calories could be taken from her fat stores in one day, before her body begins tapping into muscle/fat free mass.  She’d need to eat in order to sustain that kind of activity, which would decrease the deficit enough that she wouldn’t see even close to a lb of fat loss in that one day.  So even at max energy transfer rate, she wouldn’t see 1lb of fat loss, let alone 3.

Can you burn 3lbs of fat in one day via exercise?

No. You could run an ultra marathon and not come anywhere close to this. The average female might burn 400-600 calories per hour running. So unless you can run for 20 hours straight, without food/gels/sports drinks/etc (you can’t), you’re not getting close to a 10500 calorie deficit. And there’s no other activity that’s going to burn calories at a significantly greater rate than this 400-600/hour, even if you could sustain so much activity without reducing the deficit via food.

Even with the drugs that are typically being used (t3, clen, etc), you’d get a boost, yes…but you’d run into issues with hyperthermia if you combined those drugs with this much activity.

And regardless…the claims that were made were ‘I woke up 3lbs leaner and have no idea why’. So we’re not talking about someone who added a ton of activity. This was a situation where activity was held relatively constant.

Why do I care about this?

I don’t really. It’s just hilarious to see all these elite level coaches and competitors all thinking that something like this is possible, and absolutely nobody calling BS on it.  There were some big names attached to the thread, so I suppose there may have been some intelligent people who just kept their mouths shut (myself being one of them, until now :).  Perhaps someone could try making a similar post, without any big names attached, and we’ll see if the response is different…I’ve noticed this pattern on that particular sub.

But really…are we supposed to believe that these people should be trusted to run drug protocols in a safe manner, when they show time and time again that they lack even a rudimentary knowledge of human physiology?

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metabolic rate, runaway metabolism

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