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The Hacker's Diet by John Walker.
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How do you lose weight? Eat less than you’re burning each day.

It's simple. But simple doesn’t mean easy. Like anything else in life, successfully losing weight requires:

  • A fixation on the goal you want to achieve
  • An understanding of what’s required to achieve the goal
  • Developing a rational plan to meet your goal
  • Carrying out the plan
  • Willpower and a high tolerance for pain

Calories In/Calories Out

The way to lose weight is to eat fewer calories than you’re burning each day.

Everyone has a different daily calorie requirement based on height, weight, and activity level. Very roughly, the average man burns around 2000 calories, and the average woman around 1500 calories. Determine yours with this calculator.

A pound of fat contains about 3500 calories. Losing a pound of fat requires you to burn 3500 more calories than you eat. There’s no way around this. Fad dieting techniques like keto, paleo, intermittent fasting, etc. are all merely different ways of restricting your calorie intake.

Likewise, eating an extra 250 calories a day causes you to gain a pound in 2 weeks. Or 26 pounds a year. And this just requires one more helping at dinner, one beverage per day.

For purposes of weight loss, you could eat 1500 calories of butter a day and still lose weight. It’s not what you eat, it’s how much of it.

The Eat Watch

Imagine that you had a watch that told you when to eat. When it flashed Eat, you would eat. When you reached your calorie limit for the meal or the day, the watch would stop flashing, and you’d stop eating.

People who have been skinny their entire lives have perfectly tuned Eat Watches. When they eat over their caloric requirement for the meal, they simply stop eating. Eating past this point becomes unbearably uncomfortable.

People who gain weight easily have broken Eat Watches. Cutting calories is painful; eating excess calories is easy. It might even be easy for you to keep eating past the point of discomfort.

But this doesn’t mean you’re doomed for life. Many of us are born with bad vision, but you can get glasses to correct your problem. If you have a broken Eat watch, you can build your own artificial one, by tracking your weight and calories.

Tracking Weight

If you’ve ever tried to lose weight and measure your body, the path your body takes is startling.

  • When you first start dieting, you seem to lose 5 pounds in 2 days. Wow! What progress!
  • Then it quickly slows to a trickle. This is the plateau of misery.
  • You get antsy and frustrated, so you have a cheat meal. You stand back on the scale, and you weigh 4 pounds more. My god! All your progress is lost!
  • As you weigh yourself through the days, your spirits rise and fall with your readings. Plateaus are crushing (you’re enduring so much pain! How could you barely have lost any weight!) while the temporary losses are short-lived.

The reason for this wild fluctuation is water, influenced by salt intake. This is NOT solid body mass. Because a pound of fat requires 3500 calories, there is simply no way to gain 3 pounds of fat in a day.

At a rate of undereating 500 calories per day (which is already viscerally difficult), you lose less than 0.2 pounds of fat a day. This signal is largely lost in the noise of day-to-day weight fluctuations.

The solution to this is the exponentially weighted moving average (EWMA). This takes a moving average to smooth out daily fluctuations, and weighs recent data more strongly than past data.

The trend of the EWMA shows weight loss per week, which can then be calculated into calorie deficit per day.

Meal Planning

Pre-planning meals — how much you eat AND when — gives you a reliable daily calorie intake. If you eat only what you plan to, then you’re guaranteed to achieve your goal. (Again, simply, not necessarily easy).

You would never invest in a company that sets no budgets and whose strategy is “spend whatever we feel like day to day, and hope it’ll work out in the long run.” Not only would this be more likely to fail than methodical planning, there’d be no way to measure actual performance against goals to figure out the problems. “Winging it” in relation to your eating target is the same.

Tips:

  • Plan your meals ahead of time — specific amounts at specific times. Don’t eat any more than this.
  • Pre-planning reduces the pain of hunger, since you know you’ll have your next meal at a specific time.
  • The easy way out is to eat pre-prepared foods, like microwavable meals or liquid shakes. These reduce prep time and make calorie planning easy.
  • Measure or weigh quantities of what you eat. Highly caloric foods contain more calories in less mass than than you think (eg 20g of nuts is way less than you might guess, but has 115 calories).

The Weight Loss Journey

If you have little knowledge of calorie content of foods, and tracking weight is new to you, it may be wise to spend a couple of weeks just getting used to the actions — monitoring your daily weight and measuring your calorie spend. Once you’ve become accustomed to your weight fluctuations and the procedures, you’ll be better equipped to execute your plan.

Start your diet in a regular period when you have a regular schedule, when you have time to adjust to the diet.

The first 3 days are the hardest as your body adjusts to burning fat. You’ll feel cold, weak, irritable, tired, and a constant gnawing hunger. It is this bad, and it’s not good to sugarcoat this — better for you to know what will come and handle it better. But rest assured, it will never feel worse than this. The hunger softens...

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The Hacker's Diet Summary 1: How to Lose Weight

There’s a story about financial traders on Wall Street. A novice asks a guru, “How do you make money in the market?”

The guru responds, “It’s simple: buy low, sell high.”

The beginner replies, “How can I learn to do that?”

The guru responds, “Ah — that takes a lifetime.”

Simple doesn’t mean easy.

How do you lose weight? It’s simple. Eat fewer calories than you’re burning each day. But simple doesn’t mean easy.

What weight loss really requires is:

  • A fixation on the goal you want to achieve
  • An understanding of what’s required to achieve the goal
  • Developing a rational plan to meet your goal
  • Carrying out the plan
  • Willpower and a high tolerance for pain

This is what’s needed in any of life’s hurdles. This is precisely what losing weight achieves.

The author is John Walker, founder of software company Autodesk. He spent most of his life fat, before figuring out how the body and weight loss works. Then, in less than a year, he lost 60 pounds and kept it off forever.

This book is an engineer’s approach to weight loss, described in terms of control systems, feedback loops, measurement noise reduction, and practical problem-solving.

In the first 4 chapters, we’ll discuss the fundamentals of a successful weight loss plan. Then we’ll discuss the practicalities of starting the weight loss plan. Finally, we’ll discuss what to do when you reach your goal weight and keep it off for good.

Motivation

If you’ve tried diet after diet and failed each time, what motivates you to try again?

This book will lay out a program that makes the steps easy, and the thought of failure hard to imagine. It explores the principles of weight that other fad diets ignored, which caused you to avoid addressing the root cause. After reading this, you should think, “Hey, this isn’t hard at all! I can do this!”

And the goal is worth it. Within months, people will find it hard to imagine you as overweight. You’ll be able to walk up stairs without noticing the exertion. Once you’ve experienced the joy and confidence, you’ll never consider giving it...

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The Hacker's Diet Summary 2: Eating’s Feedback Loops

Wouldn’t it be great to have a watch that tells you when to eat and when to stop? When it says EAT, you can eat. It’d monitor what you’re eating, track calories for you. Then when it figures out you’ve had enough calories for the meal to keep your weight, it says STOP, and you stop eating. The Eat Watch would be smart enough to keep you at your daily calorie limit for your ideal weight.

Some people are born with a natural, built-in eat watch that works perfectly. Let’s call this type of person Skinny Stable Sam. They eat only the amount needed to maintain their thin bodies, for their entire life. If they eat less than what they burn, they get hungry and they eat. If they overeat in a meal, they feel uncomfortable and take longer to get hungry again, plus they eat less in a later meal. Their point of discomfort and satiety is set precisely at what their body needs.

If you’re overweight, your Eat Watch is broken in a way that causes you to gain weight over time. Let’s say that your ideal weight requires 1600 calories.

  • Instead, your Eat Watch is calibrated so that it’s set to 1800 calories. Eat fewer than these calories, and you feel intense hunger.
  • Furthermore, if you eat more than 1800 calories per day, you may not feel the same discomfort as Skinny Stable Sam. Even after you’ve stopped being hungry, you might continue to eat without inhibition — possibly until the point at which your stomach is about to burst and you physically can’t eat any more. If you’ve felt utterly unable to resist food at the dinner table, this is you.
  • Finally, if your Eat Watch were merely set to 1800 calories and stayed there forever, that’d be one situation — you’d be about 40 pounds over...

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The Hacker's Diet Summary 3: Measuring Weight

Tracking calories is critical — it’s easy to overeat, and having a strict boundary will make it less likely for you to eat past your goal. And if you perfectly measure your calorie intake, then it should correspond well with your weight loss.

But how many calories you’re eating isn’t your final goal — your weight is. Your weight keeps you honest — if you’re not losing pounds as quickly as you think you should be, then you’re probably eating more than you think, or you burn fewer calories than you estimated. Either way, you need to adjust.

If you’re serious about losing weight, you should measure your weight everyday. To do otherwise is to try to drive without looking at the road. Would you drive by looking at the road for 1 second, then covering your eyes for 4 seconds before looking again?

The Typical Weight Loss Path

If you’ve ever tried to lose weight and measure your body, the path your body takes is startling.

  • When you first start dieting, you seem to lose 5 pounds in 2 days. Wow! What progress!
  • Then it quickly slows to a trickle. This is the plateau of misery.
  • You get antsy and frustrated, so you have a cheat meal. You stand back on the scale, and you weigh 4 pounds more. My god! All your progress is lost!
  • As you weigh yourself through the days, your spirits rise and fall with your readings. Plateaus are crushing (you’re enduring so much pain! How could you barely have lost any weight!) while the temporary losses are short-lived.

No wonder you’re afraid to step on the scale! It’s like a slot machine of punishment.

The reason for this fluctuation is water. Any real weight loss (i.e. loss of fat) will happen with less than 0.3 pounds per day — and this corresponds to a high 1000 calorie deficit, which is more difficult than most can sustain. Any variation that happens beyond 0.3 pounds is almost entirely water.

  • Keep this in mind — if you drink 2 liters of water, that amounts to around 4.5 pounds. Your retention of this water is going to blow out any minor weight loss that happens.
  • Your weight can...

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The Hacker's Diet Summary 4: Planning Meals

Pre-planning meals — how much you eat AND when — gives you a reliable daily calorie intake. If you eat only what you plan to, then you’re guaranteed to achieve your goal. (Again, simply, not necessarily easy).

You would never invest in a company that sets no budgets and whose strategy is “spend whatever we feel like day to day, and hope it’ll work out in the long run.” Not only would this be more likely to fail than methodical planning, there’d be no way to measure actual performance against goals to figure out the problems. “Winging it” in relation to your eating target is the same.

Rigid planning of meals, and adherence to the plan, is the most important strategy in losing weight. You will lose some spontaneity of your eating, but you will be rewarded by weight loss.

Planning meals has these benefits:

  • It helps you avoid the in-the-moment temptation to get a plate of seconds.
  • It avoids reliance on your internal eat watch, which we already know is broken — without constraints, you will eat far beyond what your body needs for maintenance.
  • It avoids unpredictable meals, which leads to unpredictable calorie consumption. If you go to lunch without any idea of how much you’ll eat at dinner, how do you know how much to eat at lunch?

Pointers on Planning Meals

What you eat doesn’t matter as much as how much you eat. Calories per day is by far the most important number as far as weight is concerned. What doesn’t matter as much: the composition of what you eat (such as fats vs carbs vs protein), and when you eat it.

So in general, keep your current eating schedule. You can eat 3 meals a day, or 8 small meals. But keep a regular schedule.

  • As you gain experience, you may notice certain periods of the day when you’re hungrier. Then adjust your eating schedule to ease your hunger during these periods.
  • Keeping a regular schedule helps you deal with hunger. Hunger is easier to handle when you know that in exactly 1 hour and 52 minutes, you’ll be able to quench the hunger.
  • The author advises one exception, which...

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The Hacker's Diet Summary 5: Starting to Lose Weight

We've now covered all the critical knowledge and tactics needed to lose weight. Now we formally put it together into a feedback loop system that controls your weight:

  • Estimate the calories you need.
  • Plan your meals to meet your calorie target.
  • Log your weight daily.
  • Observe the trend of your weight. This gives you the truth of your net calorie balance.
  • Adjust your calorie estimate to keep track of your trend.

If you’re losing less weight than you expect, there are only two possibilities. Either you’re burning fewer calories than you expected, or you’re eating more calories than you budgeted, or both. Analyze your situation, and adjust accordingly.

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This forms the feedback loop you need to lose weight. By going through multiple iterations of measurement and adjustment, it is simple to reach your goal.

Getting Ready

If you have little knowledge of calorie content of foods, and tracking weight is new to you, it may be wise to spend a couple of weeks just getting used to the actions — monitoring your daily weight and measuring your calorie spend. Once you’ve become accustomed to your weight fluctuations and the procedures, you’ll be better equipped to execute your plan.

When you’re ready to start, follow these steps:

1) Measure your current weight and set your weight target. A general weight goal is to set your target weight based on your height and your frame

  • Each person may have stable weights that are far easier to maintain than a weight 5 pounds lighter or heavier. The author notes that 145 or 165 was easier to maintain than 155.

2) Figure out your desired deadline for reaching your target weight. Get the number of days between today and your deadline.

3) Calculate your calorie deficit. This is given by the simple formula:

(Target weight loss in pounds) * 3500 / (Days to deadline)

For example, if you want to lose 10 pounds in 2 months (or 60 days), you will need to run a deficit of (10 * 3500 / 60) = 583 calories per...

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The Hacker's Diet Summary 6: Perfect Weight Forever

The majority of people who lose weight end up gaining back every pound they lost. You might have gone through a few cycles of this yourself. You might feel hopeless that even if you do lose weight, you will inevitably gain it back — so what’s the point?

The reason people regain weight is that they don’t change their eating behaviors after they lose weight. Meeting their goal, they blissfully return to using their broken eat clock.

Assuming that you were born with a broken eat clock and it’s not possible to develop a working one, keeping your weight for a lifetime requires a lifetime of guidance about how much to eat. Specifically, this means continuing the best practices of what got you here: 1) daily weight tracking and 2) meal planning.

Someone with poor eyesight has to wear corrective lenses to see properly. Without them, she is lost. Likewise, you may have to accept that you have genetically problematic eating controls.

This is the cost of being healthy and avoiding yo-yo weight fluctuations. It’s also the cost of earning valuable freedom — in the foods you eat, your meal schedule, and how much or little you exercise. You can return to eating whatever you want — just in limited, predetermined portions.

Remember the pain you felt during your weight loss. You don’t want to go through that again, do you? Look back at your starting photo. You don’t want to look like that again, do you? It’s worth it.

Note this does NOT mean being on a diet for the rest of your life. It simply means eating at maintenance calories forever. You can still enjoy all the foods you like — just in moderation.

But if you’ve failed before, why will you succeed this time? After reading this, you now understand your body and weight to a degree you never had before. You’ve devised your own successful diet plan. You’ve stabilized your weight, rather than yo-yoing back into bad habits.

Daily Weight Tracking

Once you reach your target weight, you must not lose discipline in tracking your weight daily. Day to day variations are hard to detect in the mirror....

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The Hacker's Diet Summary 7: On Exercise

The most important thing to understand about exercise is that diet control is far more effective at causing weight loss than exercise. For most people, it is much more painful to burn 100 extra calories by jogging than it is to merely avoid 100 calories of food.

But what about gaining muscle? Each additional pound of muscle only burns 6 calories per day. And gaining a pound of muscle is far harder than you think.

This is not to say that exercise isn’t beneficial. The medical consensus is that exercise is great for overall health outcomes, quality of life, bone density, energy levels, sleep quality, etc. But merely for the purpose of losing weight, you should focus on meal planning and calorie cutting, rather than burning more calories through exercise.

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Shortform Exercise: Reflecting on Weight Loss

Think about what you’ve learned from this book and how you’ll approach weight loss now.


What were the most useful concepts about weight loss that you learned from this book?

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Table of Contents

  • 1-Page Summary
  • 1: How to Lose Weight
  • 2: Eating’s Feedback Loops
  • 3: Measuring Weight
  • 4: Planning Meals
  • 5: Starting to Lose Weight
  • 6: Perfect Weight Forever
  • 7: On Exercise
  • Exercise: Reflecting on Weight Loss