Where did the 500 number come from?

People always write that there has to be a 500 cal. deficit to lose - or they advise others to create a larger deficit if they aren't losing.

What if I have a 300 cal deficit? Is my body going to compensate because the deficit is not big enough to call on my fat cells for help?

What do you guys think?

Any long term deficit is going to cause your body to lose weight. Just at different rates... at least mathematically.

The 500 number came from this quick math:

A pound of fat is roughly 3,500 calories.

A safe amount of weight to aim to lose each week is about 1 pound.

3,500 (1 pound of fat)/ 7 (a week) = 500 a day.

That's 500 calories less taken in each day, which would mathematically result in about a 1 pound loss of fat each week.

Does that mean you believe that a 100 calorie deficit would eventually allow one to lose over a course of time? (One lb. in 35 days)

Has anyone found any research regarding the size of the deficit? As in, it must be so large before the body will start turning to fat stores.... I dunno, I'm not a scientist.

I would imagine a deficit is a deficit - regardless of how long it takes to happen. Some people are perfectly comfortable spreading weight loss over a much longer period of time. Don't know about the entire fat stores thing - I am more of a calories in/calories out sort.

If you think about it, most people gain weight slow and over time. For many of us I would guess that wasn't because of 500 over daily, it was because of small amounts over a long period of time.

In short, yes.*

In lengthy and very over-simplified example terms (because I'm no scientist):

Deb the Dieter weighs 150 pounds, and eats 1,800 calories a day to maintain that weight. She wants to weight 125 pounds and lowers her intake to 1,500 a day.

Each day her body is trying to maintain her 150 pounds (it has basic functions to continue performing in order for her to keep existing) and is looking for about 1,800 calories in order to do just that.

She's taking in fewer calories now, and so her body searches for more energy. It's getting about 1,500 calories-worth. But, where is it going to get the other 300 calories of energy from? From her stored energy.

Her body uses up the stored energy, causing her to lose some weight... doing two things. 1) She's losing weight (the whole purpose) . 2) Her body needs a little bit less energy to maintain her now lighter body, ever so slightly lowering her deficit as she continues to lose weight.

Now, again, I'm not a scientist. Nor am I an expert. This is merely how I've had it explained to me in very basic terms.

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*There are exceptions, as there are people with disorders that make weight loss much more difficult/complicated. So, this is sticking to purely the math and assuming no other obstacles.

Exactly what everyone has said so far.

Except at some point (different for everyone), the calorie deficit won't seemlessly add up the farther down you go. Creating a 1000-cal deficit each day will lose weight faster, but if that deficit is causing you to dip too low, it can actually stall your weight loss.

It is so tricky. I think that is why 500 is such a highly recommended number. Not too high, not too low.

I would imagine "they" recommend 500, as mentioned above, because it's not too high or low. Most people can handle a 500 calorie deficit, it's something they can stick with and not fall off the wagon a week or two later. It also allows enough progress (approx 1 lb/week) to keep people motivated. Sure, I would imagine you could lose weight on a 300 cal deficit, but the slow progress might be too discouraging for some people.

I agree 100%. I gained about 15 lbs. in 2010 over the course of the year. Just going by the numbers, all I had to do to "accomplish" that weight gain was take in, roughly, only about 140 calories per day more than my maintenance calories. Heck, an extra apple and a piece of cheese per day could bring me above that.

We just don't notice as much when we're taking in that few calories. We only notice when we're trying to take off weight and every calorie we have to cut seems like deprivation.

The thing is that the mathematical model of cut 500 calories a day and lose 1 pound a week or cut 1000 calories a day and lose 2 pounds a week is nice, neat, simple....but apparently wrong.

It would be nice if weight loss was actually that clearcut (although even with the above formula you first have to know how many calories you burn each day so that you know how much to cut. Do you burn 2500 calories a day or 1500 or what?)

A recent study basically says that the formula is wrong. It doesn't account for various thing such as metabolism slowing as weight is loss, losing muscle as well as fact and other factors. Basically the article says it takes much longer to lose weight than the formula would show.

Here is a link to an article explaining the study:

http://www.webmd.com/diet/news/20110...ct-weight-loss

Here is a link to the actual article (you have to register and then can read the article free)

http://www.thelancet.com/journals/la...812-X/abstract

Here is a link to the author's body weight simulator. FWIW, I found it very accurate for my weight loss over the last year. The usual formula would say that I should have lost much more over the last year. I've counted calories very carefully and have lost weight but not nearly what the usual formula says I should. However, if I run this simulator it is very accurate for my weight loss. Many people won't like it because it shows weight loss as much slower than we would like but I think it is more accurate:

http://bwsimulator.niddk.nih.gov/

It's very difficult to determine exactly how much of a deficit you're actually creating, so in some ways the numbers are completely "theoretical."

Let's just say that you are able to maintain your weight on 2500 calories. In theory, if you raise your calorie intake to 3000 calories, you would gain one pound per week.

But that's not always what happens. Some people will gain more than a pound, and some people won't gain anything. Many research studies have been done trying to get folks to gain weight by adding extra calories to their diet - and the results were rather interesting. Some people don't gain weight easily. Give them a lot of extra food, and their body burns it off. Some people gain weight extremely easily.

And the same results are often seen with weight loss. Some people have bodies that adapt very well to calorie restriction. When they eat less, they burn less. So it can be difficult to create a 500 calorie deficit. Because if they cut 500 calories from their normal diet, but their body lowers their metabolism (or causes them to feel sluggish so they move less without realizing it) by 200 calories, that 500 calorie deficit is now only a 300 calorie deficit.

Essentially, the deficit can usually only be determined by hindsight. If you're losing 1 lb per week, consistently, you've managed to create a 500 calorie deficit (we think).

Now there are ways to do better math, but most of those methods are really only useful in the lab.

For the real world, we have to experiment and just see what happens.

In theory, if you create even a 35 calorie deficit, you would lose a pound, but it would take 100 days.

The problem arises in determining that you've created a 35 calorie deficit. You can't just cut 35 calories from your normal calorie level, because you can't be sure that your body isn't going to compensate in some other way (not to mention that calorie counting would be difficult to calculate so precisely).



Personally, I think we get too caught up in the numbers we can't control. We can't precisely control the calories our bodies burn. We can much more precisely control the calories we take in.

The easiest way to create weight loss, is to not worry about the deficit numbers or the calories out part of the equation at all.

Just start with a calorie level and see how much weight you lose. If you're consistently losing a pound a week - you've created a deficit large enough to allow you to lose a pound per week. You don't have to worry about how much of a deficit you've created, or how you've done so.

If you lose only a half a pound, you can try cutting your calories another 250 per day - and you may be able to increase your weight loss to one pound per week. Maybe not. Or if you don't want to cut your calories, you can try exercising more (but not eating more) and see if that creates more of a deficit.

You don't ever really need to know or even try to manipulate the exact deficit numbers, you just have to move more, eat less and watch the scale.

I've found that I lose more weight and am less hungry on lower-carb, so I try to eat relatively low-carb. If I wasn't willing to eat low-carb, I could cut my calories more drastically and would have to endure more hunger - but I have both options.

(Not everyone loses better on low-carb, this was just a personal example).

I don't know why I burn more calories on low-carb. Two possibilities I've noticed is that I have more energy - so I probably move more and therefore burn more calories without even thinking about it. And another is that my body temperature is higher on low-carb, and it takes more energy (calories) to maintain a body temperature of 98.4 than it does my high-carb body temperature which is usually in the low to mid 97's (and sometimes even lower).

Well said! I go into a hissy fit (something I need to work on) when people start talking about tracking deficits, number of calories "burned" during exercise, etc. For the reasons you outlined, it's difficult and often inaccurate to focus on "burning off" a certain number of calories per day. Exercise is so important for many reasons, but I think trying to link it too directly to weight loss (and getting disappointed when after 7 days those 3500 calories "burned" from 5 hours on the elliptical machine doesn't translate into a pound lost) isn't helpful.

I agree. This time around, I've tried to put exercise in a category all its own---i.e., for general fitness, well-being, and muscle tone rather than as a gauge of how much more I can eat or how much more I'll lose.

Even though I do count calories and believe in the basic formula, I try to focus more on just putting one foot in front of the other and practicing behaviors that I know will eventually lead to weight loss (and have!) rather than having an expectation that I should lose X amount by X date. That would set me up for disappointment.

Interesting, Koshka. Thanks for posting!

I am happy I never heard of deficits when I started dieting. All this formula activity would have just confused me and probably would have scared me off, if I thought I had to follow some kind of deficit formula. I simply ate less calories and I lost weight. I did count calories but didn't give a darn about deficits.

When your so close to your goal weight & have been at a plateau for four months, despite cutting cals, increasing cals, increasing exercise, increasing strength training, counting every morsel & every deficit......let me know what's next.
At this point, I'll pretty much try anything, including standing on my head!

As a matter of fact, I am eating clean & agressively trying to live sugar free!