How much weight can one lose in two weeks?

July 22, 2007 9:01 PM

What's the most number of pounds a person can lose in two weeks? and how?

If a person has 3-4 hours a day for exercise, what's the most he/she can lose? I am sure it depends on genetics, current muscle mass, etc, but what would you say is doable?

If you have your own experience to back it up, that'd be great...including food/calories intake as well as the workout regiment.

posted by icollectpurses to health (17 comments total)

A bunch of people are going to jump in to tell you that loosing more than 2 or 3 lbs a week is unhealthy, or at least signs of a dangerous crash diet. I suppose 5lbs is doable without seriously damaging yourself permanently...
posted by wfrgms at 9:19 PM on July 22, 2007

For what it's worth, at my most successful I have done about five pounds over two weeks, with interval training and weights three times a week and a very modest change to my diet (cutting out beer and confectionery). On the other hand, I've never been that overweight, and I'm a mid 30's male with reasonable muscle mass underneath.

My understanding is that many people can lose rather more than that - say 10-15 pound, BUT:
- a little bit of that is stored glycogen in your liver and muscles and therefore a one off
- quite a lot of that is water retention, and therefore a one off
- some of the remaining extra is lean tissue, and therefore NOT GOOD FOR YOU
- once you go past 1-2 lb per week your body will wise up and your metabolism will go down, so this is not sustainable and will actually make more weight loss harder
- if you're a man, and fairly overweight, you'll lose more than a merely chubby woman, as every woman who's ever been in a mixed Weight Watchers group will attest.

Anyway, don't do it.

Further note - three to four hours a day is likely going to be an unsustainable effort if you have been sedentary, and unless it's carefully supervised, you may hurt yourself too.
posted by i_am_joe's_spleen at 9:46 PM on July 22, 2007

You can lose a lot of weight very quickly if you don't eat much. I know from personal experience (while ill and eating very little) that it is possible to lose 20lbs in a month. This is definitely not healthy though, just an answer to your (literal) question. If you want to lose weight, do it reasonably and responsibly.
posted by ssg at 9:46 PM on July 22, 2007

Well, I think it's technically possible to lose 10 pounds or more, but a lot of that will probably be water weight, which will come back pretty quickly.

The standard formula for losing actual fat is
1 lb = 3500 calories. To lose 1 lb, you have to create a 3500 calorie deficit. If you need 2000 calories a day to "break even," and you eat 2000 calories in a day, you won't gain or lose. If you eat 1000 calories, you would lose 2 lbs in a week. If you eat 1000 calories, plus burn off 1000 by exercising, you could lose 4 pounds a week.

That's a simplistic way of looking at it, which doesn't take into account that your body will want to hang on to the weight by slowing you metabolism down as a defense against what it sees as starvation.

If this is something you are actually wanting to do, good luck, but be healthy.
posted by The Deej at 9:50 PM on July 22, 2007

i_am_joe's_spleen has a lot of great info there. I would say 15lbs is very doable in 2 weeks.

I would not even try to exercise 3 to 4 hours a day, that is kind of absurd and more dangerous (assuming you are semi-sedentary right now) than actual crash dieting in 2 weeks. I don't know that any top athlete would even exercise that amount of time very regularly.

I have lost 20 lbs in 3 weeks before doing a low carb diet coupled with low calories (~1200-1500 a day). I was not that overweight (180 at 5'6" and fairly muscular) and realized it was unhealthy. A seriously obese person could lose 30lbs in two weeks (look at biggest loser for example).

It sounds like you really want to lose a ton of weight in 2 weeks, that this isn't purely speculation. I wouldn't do it if I were you, since it sounds like you have never done anything like it before. But with that said a good way to do it would be the induction phase of south beach diet (Adkins but without all the unhealthy fats) and watch calories as well. Space the meals out as much as possible to try to keep up your metabolism (although it will fall anyway w/ calorie deficit). Walk/jog/elliptical 30-45 minutes a day for exercise.
posted by wolfkult at 9:58 PM on July 22, 2007 [1 favorite]

Have you ever seen The Biggest Loser? In a controlled environment, with a trainer, a doctor, and working out 5/6 hours a day, eating low carb, low fat, high protein with veggies, about 1200 - 1400 calories a day female, the first week of the show every female loses, on average, between 6-14 pounds, and the second week the results are pretty much the same. Males on a 1800 calorie a day meal plan with the same kinds of exercising usually lose around 10-18 lbs each week the first two weeks. You know the whole 'in the beginning it's mostly water weight' thing so I'll spare you that.

If you stayed away from weight training totally (which you should if you only have two weeks and are going for full out weight loss) and go full out cardio/fat burning on machines for 3-4 hours a day, and eat low calorie meals (no starches, low fat, high protein, fresh veggies), you have the potential to lose your maximum. There's no way any of us can say what your maximum is. If you weigh 400 pounds, you could easily lose 20 pounds the first week, but if you weigh 150, you couldn't.

All that said, I'm certainly not advocating that anyone lose 10 pounds a week, as it seems drastic, risky and shortsighted, but it is physically possible.
posted by iconomy at 10:21 PM on July 22, 2007

I was losing 20 pounds a month or so for a couple of months starting in the summer of 2005. Here is a graph of my weight that I posted in November of that year. I ended up getting down to 188. I don't know if it's the maximum I could have done, but it was certainly sufficient.
posted by delmoi at 10:36 PM on July 22, 2007

When you say "lose weight" I assume you mean "lose fat". You can lose weight by reducing the amount of water, muscle or fat in your body. The way that some fad diets work is generally by making you lose water or muscle (by eating so little your muscles atrophy).

From the NHS website:

Gradual weight loss of around 0.45-0.9kg (1-2lb) per week is usually recommended.

From the National Institute of Health:

Slow and steady weight loss. Depending on your starting weight, experts recommend losing weight at a rate of 1/2 to 2 lbs per week. Weight loss may be faster at the start of a program.

If you want to lose much more than that, talk to your doctor first. If you eat too little there's a big danger that you will lose muscle, slow your metabolism, and just put even more fat back on as soon as you come off the diet.
posted by TheophileEscargot at 11:18 PM on July 22, 2007

Oh, and if we're doing graphs mine's here. Yes, I'm working on keeping that long tail under control...
posted by TheophileEscargot at 11:26 PM on July 22, 2007

Fastest weight loss I ever achieved was 10kg (22lb) after a two week water-only fast, about twenty years ago. If I remember right, my starting weight was somewhere around 140kg at the time. Once I started eating again, about 3kg went back on in a day (so I guess that was glycogen/water weight).

I did the fast just to see what fasting for two weeks was like, not in order to lose weight. It was very interesting, but it screwed up my metabolism and left me feeling pretty lethargic for a couple of months afterward.

I absolutely do not recommend fasting, or any other form of crash diet, as a weight loss method. It will do you more harm than good.
posted by flabdablet at 11:51 PM on July 22, 2007

Oh yeah, I forgot the time my sister was at death's door in the ICU in a foreign country. If you get on a plane, fly 30 hours straight, and then sleep no more than 4 hours a night, eating two meals a day only for two weeks, you can lose 15 pounds just like that.

I throw that in for comparison stupid vs sensible in the same person.
posted by i_am_joe's_spleen at 12:46 AM on July 23, 2007

I lost around 15 pounds over a month or two without really trying, just by removing the carbohydrates from my dinner each night. It was during a winter of weight-lifting and so I was probably adding pounds of muscle during this time. This is the only diet I've ever needed and it worked wonderfully. Chicken breasts and salad, e.g., is a good dinner. Separating protein and carbohydrates works; it's sustainable, healthy, and doesn't rob you of any of the real pleasures in life. (You should stay away from sweets though.)
The best way to exercise is variation, i.e. run and swim on alternate days or try 5-day cycles of running/rowing/swimming/weight-lifting/rest. Keeps you entertained and you can push yourself hard every day because you're not repeating the exact same exertions.
I don't how exactly how many pounds it is healthy to lose, but the healthy way to lose weight is with sustainable habits and not with drastic measures. If you don't do anything ridiculous I don't think you'll be in danger of losing too much too quickly.
posted by creasy boy at 1:33 AM on July 23, 2007

Is this a theoretical question, or do you have some objective?
If this is for the long term, why do you mention 2 weeks? Do you want to look good in a bathing suit in 2 weeks and not care how you look in 3 weeks? If so, is this more about shape than weight?
Or do you have a weigh-in?
posted by MtDewd at 5:55 AM on July 23, 2007

I lost a lot of weight on the first two weeks of the South Beach Diet - like 15 pounds, and it stayed off. Granted, I continued to follow phase 2 of the diet.
posted by chickaboo at 10:29 AM on July 23, 2007

I was losing 20 pounds a month or so

Wow delmoi, that's awesome. If I could do that, I'd be at my goal weight in 2 months!

Nice photo, too, by the way.
posted by The Deej at 10:33 AM on July 23, 2007

When I was 16, I lost 20 lbs in 3 weeks by eating an extremely low calorie diet (I think my system was to have an orange for breakfast, baby carrots and a handful of pretzels for lunch, and a quarter of a normal portion of whatever my parents served for dinner) and doing cardio for 2 hours a day most days of the week. I was a cranky bitch for those 3 weeks, and it was completely unhealthy, but I got what I wanted out of it.

Surprisingly, I kept those 20 lbs off with absolutely no further starvation dieting (I continued to exercise but more like an hour a day) until college ... when the shit hit the fan. Maybe that's why I have so much trouble losing weight now that I actually need to.
posted by tastybrains at 3:22 PM on July 23, 2007

I recently got back into eating right and getting plenty of exercise. In the first week alone I lost around 3kg - 6.6lb. I wasn't starving myself, but I think that a lot of weight lost initially is food in transit through the gut.

Since then I have been eating a moderate breakfast, a light lunch and a reasonable dinner, no sugar and no snacks. I have a fairly active job, and I have walked over 350k since the end of May, and lost over 13 kg (28lb) while increasing my endurance and aerobic fitness.
posted by tomble at 5:16 AM on July 24, 2007