reposted from: http://www.fourmilab.ch/hackdiet/e4/rubberbag.html
The Hackers Diet describes how the body is essentially just a rubber bag.
If, over a period of time, the calories in the food you eat exceed the calories you burn by 3500, you'll put on about a pound. Conversely, if you reduce your food intake so that you burn 3500 calories more than you eat, you'll lose about a pound.
At 5' 7" I'm using 1700 - 2417 depending on how my frame is defined. I suppose I'm medium frame (i need to check how this is defined), if so, the I use 1796 - 2245 calories a day.
Suppose you start putting in an extra 250 calories a day. That sounds like a lot, but consider the following:
| Savoury Snack | Calories |
|---|
| Ice cream cone | 220 |
| Doughnut, glazed | 225 |
| Oreo cookies, 5 | 250 |
| Beer, 2 cans | 300 |
| Chocolate shake | 375 |
| Pecan pie (1/6 pie) | 550 |
These little compensations for life's vicissitudes can add up. Indeed they do…to the tune of an extra 1750 calories per week based on a daily excess of 250 calories (250x7=1750). The weekly surplus of 1750 calories equals half the calories in a pound of fat (3500/2=1750). As week gives way to week, you'll find you're gaining about half a pound a week. Two pounds per month. About 25 pounds a year, by which time none of your clothes will fit, you'll look awful, be depressed about the situation, and feel unable to get a handle on it unless you've grasped the simple arithmetic at the heart of the problem.
But consider the flip side of this calculation. Passing by any of the treats listed above, or its equivalent in other foods, hardly constitutes starvation or survival rations. And yet, simply by eating that little bit less every day for a year, you can subtract 25 pounds from your weight in the space of a single year (assuming you weren't gaining weight before).
I know this. But I bet the vast majority don't! Actually I marvel at the weigh the body can control weight .. more or less. In the last year (May 2007-June 2008) I've put ONLY about 18 pounds. That's 1.5 pounds a month or an excess of 3500 x 1.5 calories or 5250 calories per month or 175 calories a day. If I'm using up 2000 calories a day the body is controlling my weight to within 175/2000 or 9%. Thats not bad but its just not good enough! After a decade I'd be 12 stone heavier!! Rather than putting on 18 pounds and going on a diet I'd rather control my weight so that I'm never heavier than 5 pounds from my ideal weight.
Assuming my ideal weight is BMI 21 (there is some evidence for this that I discussed in an earlier
blog) then I need to get down to 9st 8 pounds - the weight I was nearly in Corfu 20 years ago (9st 13 pounds). My tactics are to
lose a pound a every week, in total 20 pounds to get down to 11st 1 pound (BMI 24.9, 155 pounds) by February 2009. Then set myself another target of losing another 20 pounds (9st 8 pounds - 134 pounds, BMI 21) by autumn 2009. Then stick at that weight (or at least within plus/minus 5 pounds as advocated in The Hackers Diet) ... for life!!
The Hackers Diet:-
The stark reality is that permanent weight control requires permanent attention to what you eat. Life long, permanent attention. The monumental pile of nonsense, mysticism, and bad advice associated with dieting stems from the all-too-human tendency to deny this simple fact. But fact it is, and like most unpleasant facts, it's best faced squarely and treated as a challenge to be overcome.
Another unpleasant fact of dieting it's worth facing up front is that while you don't need to go hungry to maintain your weight, you will need to go hungry in order to lose it. It's the rubber bag again. The only way those fat cells are going to be persuaded to dig into their reserves and start dumping them back into the bloodstream is by eating less food than's needed to fill the bloodstream with nutrients. When you do that the hunger alarm is going to go off: “Hey! Up there! Not enough food down here! How about sending down some pizza?”
This is not at all pleasant, but it needn't be incapacitating. Further, you only have to put up with it for a limited amount of time and, with this plan, you'll be able to watch your progress, know how long you'll have to spend to achieve your ideal weight, and build ever-growing confidence in your ability to control your weight as you wish.
Many things in life are unpleasant. Most are far more irritating than the day to day process of losing weight, and few yield comparable benefits. Controlling your weight holds the key to a reward no amount of money, no degree of knowledge, no position of power or influence can bring: a longer life and better health to enjoy it more.
And as with many challenges, you can turn the discomfort of dieting into an advantage once you've succeeded. For what better motivation is there to maintain your weight than recalling how awful you felt when overweight and what you went through to shed that excess poundage?
This isn't to imply that losing weight, even many pounds in a relatively short time, is akin to a stint in the Siberian Gulag. Cutting your food intake by 250 calories a day, the equivalent of foregoing french fries with your lunchtime burger or passing up your mid-afternoon “pick me up” candy bar, is enough to tilt the balance so you'll lose two pounds a month. Weighing the prospect of being 25 pounds lighter in a year against that little morsel of food each day shows how effectively you can manage major changes in your weight once you master the tools that allow you to make such decisions intelligently.
Water flow is a major component of weight gain or loss.
Most of the changes in weight you see have nothing to do with how many calories you're eating or burning. Instead, all you're seeing is how many pounds of water happen to be inside the rubber bag at the moment. How many bleak mornings of dark despair endured by forlorn dieters who indulged in a bowl of salted popcorn at midnight then slaked their thirst with a large glass of water in the middle of the night, would have been taken in stride had only the implications of human being as water pump been fully comprehended?
From an engineering standpoint this is a simple system. We have virtually no control of what comes out; that's just the waste products of the factory. We have little effective control over what we burn: in theory our bodies are at our command but the constraints of modern life sorely limit the extent we can exercise.
Consequently, the only real control we have is over what goes in: what, when, and how much we eat.
Weight control can be reduced to a very simple matter of arithmetic.
Total the number of calories in the food you eat per day, averaged over a period of time. Take the number of calories you burn per day, roughly the same for everybody of your sex, height, build, and level of activity. Subtracting the calories burned from the calories eaten gives excess calories per day. This number times thirty is excess calories per month. A pound of fat is equivalent to about 3500 calories. If you eat 3500 calories more in a month than you burn, you'll gain a pound that month. If you burn 3500 calories more than you eat, you'll lose a pound. All the weight you gain or lose is the consequence of these simple numbers. The most advanced racing engine is, basically, an air pump. Humans, notwithstanding our pretensions of transcendence are, at a comparable level, water pumps. Every day, the quantity of water we take in and dispose of dwarfs the other physical interactions with our environment. This means that
day to day weight figures primarily measure only how much water happens to be inside the rubber bag at the moment.
They're of no use in managing one's health. Instead, it's necessary to extract the signal from the noise, the reality from the raw data. Learning how to do this and applying that information to controlling your weight will be discussed in the Signal and Noise chapter.
It's an exciting breakthrough to find that statins not only lower cholesterol but also rev up the cells' own DNA repair kit 
