Based on my personal stats – why super rapid weight loss would be nearly impossible

So, I keep seeing posts pop up with questions about how to lose X number of pounds in X number of days/months. Usually the number of pounds is high, the number of days/months is low, and OP is trying to meet a pretty much unattainable goal. If you’ve been here on the forums for a while, you’ve read the general figures over and over:

1 lb = 3500 calories
Maximum safe rate of loss = 1-2lb/week
Minimum safe calories/day for a woman = 1200
Minimum safe calories/day for a man = 1500

Aside from the (pretty close to) fact that losing weight too fast usually means that you won’t maintain that weight loss and will possibly even gain back more than you lost to begin with (because nobody looking for a quick fix is going to believe that anyway), I thought I would post up my stats as a fairly average, moderately overweight, 30 year old woman, and what the various CICO methods will do for me in terms of rate of loss to illustrate that even a 2lb/week loss is a bit much.

So, here goes. If you want to see the spreadsheet/calculations that brought me to these conclusions, feel free to look HERE: https://drive.google.com/file/d/0B1Mu6rDkPKOySXpBRlQ5VXFoalU/view?usp=sharing

My Current Stats (imperial units – lbs, inches, etc):
Weight: 175.6
Height: 68
Waist (at naval): 35
Hips: 42.5
Wrist: 6.8
Forearm: 11
Lean Body Weight: 128.4
Body Fat Percentage: 26.9% (http://www.livestrong.com/article/90931-measure-body-fat-percentages-calipers/)
BMI: 26.7

My current goal weight is 155, mostly because that is 40 lbs from where I started in January, and is pretty much the lowest I can ever remember being since high school. I may adjust once I get closer, but for now, let’s say I have 20 lbs left to lose. That will put me at a BMI of about 23.5, but hopefully a lower BFP, as I’m incorporating strength training as well. Just using MFP at the fastest possible setting that it allows, this will take me a little over 13 weeks/3 months. That’s if I get back on that track. I’ve lost my first 20 pounds in about 4 months so far.

Here’s what my MFP set-up looks like at 1200 calories:

Based on MFP
TDEE (sedentary): 1960
Minimum net calories: 1200
Minimum deficit: 760
Max lb/week loss: 1.5
Average calories burned/day (last 30 days): 652
Average daily calorie allowance to lose 1.5 lb/wk (last 30 days): 1852
Average daily calorie allowance maintain (last 30 days): 2612

If I use a TDEE-X% method instead, and don’t eat back exercise calories (since they're already figured in), I have the following options. Notice that, in order to lose even 2 lbs/week, I would have to consume under 1200 calories without exercising or less than 1500 calories exercising 3-5 hours or 5 times/week. I can’t even imagine doing the workouts I do on that few calories. I just wouldn’t make it. I could probably eat under 1200/day if I just sat in front of the TV all day – that is if I didn’t fall prey to boredom snacking.

Based on Scooby's Workshop http://scoobysworkshop.com/fat-loss-plateau-calculator/

BMR 1590
TDEE (sedentary) 1909
TDEE (3-5 hours moderate exercise) 2465

TDEE (sedentary-20%) 1527
Deficit (sedentary-20%) 382
Loss Rate lb/wk (sedentary-20%) 0.8
TDEE (sedentary-30%) 1336
Deficit (sedentary-30%) 573
Loss Rate lb/wk (sedentary-30%) 1.1
TDEE (sedentary-40%) 1145
Deficit (sedentary-40%) 764
Loss Rate lb/wk (sedentary-40%) 1.5

TDEE (exercise-20%) 1972
Deficit (exercise-20%) 493
Loss Rate lb/wk (exercise-20%) 1.0
TDEE (exercise-30%) 1726
Deficit (exercise-30%) 740
Loss Rate lb/wk (exercise-30%) 1.5
TDEE (exercise-40%) 1479
Deficit (exercise-40%) 986
Loss Rate lb/wk (exercise-40%) 2.0

Based on Katch-McCardle http://iifym.com/tdee-calculator/

BMR 1624
TDEE (sedentary) 1949
TDEE (exercise 5x/week) 2375

TDEE (sedentary-20%) 1559.2
Deficit (sedentary-20%) 389.8
Loss Rate lb/wk (sedentary-20%) 0.8
TDEE (sedentary-30%) 1364
Deficit (sedentary-30%) 585
Loss Rate lb/wk (sedentary-30%) 1.2
TDEE (sedentary-40%) 1169
Deficit (sedentary-40%) 780
Loss Rate lb/wk (sedentary-40%) 1.6

TDEE (exercise-20%) 1900
Deficit (exercise-20%) 475
Loss Rate lb/wk (exercise-20%) 1.0
TDEE (exercise-30%) 1663
Deficit (exercise-30%) 713
Loss Rate lb/wk (exercise-30%) 1.4
TDEE (exercise-40%) 1425
Deficit (exercise-40%) 950
Loss Rate lb/wk (exercise-40%) 1.9

Based on Harris-Benedict http://iifym.com/tdee-calculator/

BMR 1595
TDEE (sedentary) 1914
TDEE (exercise 5x/week) 2333

TDEE (sedentary-20%) 1531.2
Deficit (sedentary-20%) 382.8
Loss Rate lb/wk (sedentary-20%) 0.8
TDEE (sedentary-30%) 1340
Deficit (sedentary-30%) 574
Loss Rate lb/wk (sedentary-30%) 1.1
TDEE (sedentary-40%) 1148
Deficit (sedentary-40%) 766
Loss Rate lb/wk (sedentary-40%) 1.5

TDEE (exercise-20%) 1866
Deficit (exercise-20%) 466.6
Loss Rate lb/wk (exercise-20%) 0.9
TDEE (exercise-30%) 1633
Deficit (exercise-30%) 700
Loss Rate lb/wk (exercise-30%) 1.4
TDEE (exercise-40%) 1400
Deficit (exercise-40%) 933
Loss Rate lb/wk (exercise-40%) 1.8664

Based on Mifflin-St Jeor http://iifym.com/tdee-calculator/

BMR 1564
TDEE (sedentary) 1877
TDEE (exercise 5x/week) 2287

TDEE (sedentary-20%) 1501.6
Deficit (sedentary-20%) 375.4
Loss Rate lb/wk (sedentary-20%) 0.8
TDEE (sedentary-30%) 1314
Deficit (sedentary-30%) 563
Loss Rate lb/wk (sedentary-30%) 1.1
TDEE (sedentary-40%) 1126
Deficit (sedentary-40%) 751
Loss Rate lb/wk (sedentary-40%) 1.5

TDEE (exercise-20%) 1830
Deficit (exercise-20%) 457.4
Loss Rate lb/wk (exercise-20%) 0.9
TDEE (exercise-30%) 1601
Deficit (exercise-30%) 686
Loss Rate lb/wk (exercise-30%) 1.4
TDEE (exercise-40%) 1372
Deficit (exercise-40%) 915
Loss Rate lb/wk (exercise-40%) 1.8296


If I wanted to lose this last 20 lbs in just a month (4.3 weeks), I would have to bump up my loss to 4.7 lbs/week. That would be a daily calorie deficit of 2326, which is 46 calories more than I’d even be eating in a day following the most conservative plan above.

Solely following MFP, if I continued exercising at the same rate I have been, I would only be able to eat 286 calories each day. Not likely that I would be able to keep up the same amount of exercise.

If I wanted to increase my exercise to allow me to eat at the minimum level of 1200 calories, I would have to burn at least 1567 calories through exercise each day. That’s 915 calories or 140% more than my average. Now, keep in mind, I already exercise 3-5 hours each week, which is 35-60 minutes, 5 days/week. To increase that much, assuming I was able to keep the same intensity, I would have to add an EXTRA 49-84 minutes 5 days a week, for a total of 84-144 minutes 5 days/week. At first glance, it looks doable. But, remember, I’d only be eating 1200 calories. It’s not likely I would be able to maintain my current level of exercise, let alone increase it 140%.

If I wanted to keep eating the same amount I’m allotted by MFP right now, I would have to burn an average of 2247 calories/day through exercise. That’s 245% more than my current average. Also, it’s 119% more than I would actually be CONSUMING each day. Assuming I could somehow manage to continue the current intensity of my workouts, I would have to work out 120-207 minutes, 5 times per week. That’s 2-3.5 hours! Even if I decided to split it between all 7 days, it would be 86-148 minutes EVERY day.

Beyond how HARD it would be to lose weight so quickly, doing so as an average person with a small weight loss goal outside of professional medical advice is just plain dangerous. If you go the eating less route, you risk malnourishment. If you go the extreme amounts of exercise route, you risk injury, both from increased exercise volume as well as lack of coordination due to exhaustion (since you aren't fueling your body enough to support all that exercise). Plus, rapid weight loss leads to hanging skin which probably won't fit into your beach body goals.

Bottom line, be the turtle, not the hare. And check out this post for specific advice on how to actually go about it:

http://community.myfitnesspal.com/en/discussion/1080242/a-guide-to-get-you-started-on-your-path-to-sexypants#latest