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The Definition of Diet Success
Why every diet "works" and almost no diet really works
Here's my definition of a successful diet in one sentence:
Diet success means sustained, sustainable, effortless
weight loss of 4-8lbs/mo or more for at least 30 days leading to normal weight.
Almost everything else is a failure.
And in one paragraph:
Diet success means weight loss of at least 4-8lbs/mo for at least 30 days but probably 6-18 months until a BMI of <25 is reached. Until normal weight is reached there is no feeling of deprivation, constant hunger, sacrifice, no "counting days until the diet ends,” craving forbidden foods, or need for invasive interventions like fat camp or rehab-style environments. It has to work in your day-to-day life.
I’ve been told that my definition is “extreme” and “unreasonable” and “unlikely.” Let's break it apart and I’ll tell you why I think it’s actually pretty reasonable.
Normal Weight by BMI
Normal weight is defined as a BMI < 25. I think this is good enough.
If you’ve never calculated your BMI, it only depends on your height and weight. Look for BMI calculators, there are hundreds on the internet. My current BMI at 6’1 is 32.8 - category obese. This is a huge improvement :)
BMI is a good enough measure for Obesity
Honestly, why not. If you’re not a professional bodybuilder or athlete, it tracks pretty well. It’s easy to measure, and most body fat measurement methods aren’t much better. We could also use 20% body fat for men and 30% for women, or waist measurement, or clothing size, or compliments you get from strangers.. but this one just requires you to type 2 numbers into a calculator, and 1 of the numbers never changes. If you have a scale and know your height, you can do this in seconds.
If you’re trying to track your progress toward not being obese, the BMI, rough as it is, is easily good enough.
If you currently play in the NFL, or are getting ready for the Mr. Olympia contest, please feel free to disregard this post.
BMI < 25 because why not aim at Normal Weight
It’s the official definition of normal weight. Am I going to be mad at you if you only reach BMI 26? Of course not. But normal weight is clearly the goal for a fat loss diet targeted at overweight and obese people.
A little bit like driving across the country from N.Y.C. to L.A. You can just head west for a long time, and putting “California” into your GPS is good enough for the first 90% of the drive. You can worry about the exact street address once you’re within a couple hundred miles.
Don’t worry about muscle loss in obese people on sustainable diets
There are definitely ways in which “weight loss” can be unhealthy, e.g. when you lose a disproportionately high rate of lean vs. fat mass. It’s generally thought that it is impossible to lose zero lean mass while losing fat, but it should only account for ~25% of the total mass lost.
Alarmingly, there are studies showing that patients on some of these new “miracle” weight loss drugs lose, on average, 40% of their weight as lean body mass. That is quite a lot higher than considered optimal.
The reason I’m not worried is that the way we’re setting up our definition of sustainable fat loss, you will not be in a massive caloric deficit. There will be little need for the body to scavenge your existing lean body mass into blood glucose. That said, you’ll lose a bit of lean body mass, that’s unavoidable. Even body fat contains some lean body mass.
This is for quitting obesity. If you’re a bodybuilder trying to get into contest shape, it’s a different animal as you don’t have the body fat reserves on you that us obese people do.
Should you still be worried about losing too much lean body mass on such an “extreme” diet as ex150, get a DEXA scan and repeat it periodically when you’ve lost a bunch of weight.
Sustained & 4-8lbs/mo
Sustained probably means at least 6 months. Let’s be honest: if you’re obese, it’ll take you at least several months to get to normal weight. Even if you lose weight rapidly with no hiccups, it might take over a year.
Let’s do some examples:
To lose 50lbs at 10lbs/mo will take you 5 months.
To lose 50lbs at 5lbs/mo will take you 10 months.
To lose 50lbs at 1lbs/mo will take you 50 months or 4.1 years.
To lose 100lbs at 10lbs/mo will take you 10 months.
To lose 100lbs at 5lbs/mo will take you 20 months, or 1.6 years.
To lose 100lbs at 1lbs/mo will take you 100 months or 8.3 years.
So why not lose fat rapidly? Do you have 8.3 years to maybe lose weight? If we’re going to experiment and one round of trials takes 10% of your lifetime, I fear we might not make it in time.
In other news, if we lose fat at a much lower rate than 4-8lbs/mo (depending on a few factors like height, weight, and more), we won’t even know if our experiment is working. There is natural fluctuation in body weight. If your signal is only 1lb/mo, how are you going to pick that out of the noise? Drinking a tall glass of water will negate the entire experiment. People often fluctuate by multiple pounds during the course of the day, and that’s without working out, sitting in the summer heat, or any illness. So we need a signal that can break through the noise.
As a rule of thumb, a 6’3 active male aged 20 will lose the same amount of fat more quickly than a 4’8 sedentary female aged 64. Imagine where you are on that scale and set your expectations accordingly.
I am 6’1, late 30s, male. I’m moderately active at best, with a daily 45 minute walk as the most “exercise” I do. I’ve lost exactly 9lbs/mo for exactly the last 5 months. 45lbs in total, started 150 days ago today, a total coincidence. A taller, younger, more active guy might’ve lost even more. It’s absolutely doable. This is why I’m setting 4-8lbs/mo as the minimum to establish a strong signal.
After publishing this I realized: of course I wasn’t actually on ex150 the entire time since I first started it. If my calculation is correct, I spent 121 days (4.03 months) on the diet, netting a loss of 0.37lb/day or just over 11lbs/month. The 9lbs/mo is including diet breaks, failed experiments, and other incidentals - making it a pretty reasonable real-world figure, I think.
Q: But isn’t slower weight loss healthier/more sustainable/better/doesn’t make you yo-yo back up?
A: No. It just delays failure. You’re being set up not to succeed, allowing you to blame your willpower when it inevitably fails to produce results long-term.
30 Day trials uncover Water Retention and Delayed Caloric Bankruptcy
I mention 30 days specifically besides the “sustained” weight loss because I consider it the minimum for a serious diet experiment or study. Anything less and you just can’t tell if your experiment worked or not.
Almost any diet will "work" for 1-2 weeks if by
“work” you mean "lose 5-10lbs of water weight."
There are at least 2 reasons why you should run any diet experiment for at least 30 days:
Delayed caloric bankruptcy
Initial Water Retention is often huge, but plateaus in 3-10 days
Water retention is a huge factor in almost all dietary changes, and ignoring it immediately invalidates your results because you’re not measuring fat loss, only a one-time shift in water weight.
Here are some things that cause big increases in the levels of water retention in the body:
Carbs (→ insulin)
Protein (→ insulin)
There are others, but most people probably aren’t going to randomly introduce creatine or potassium into their diets.
When you change your intake of any of these factors, or even combine them, it will cause your body to either store way less or way more water. I’ve seen weight increases of 6lbs and decreases of 4lbs in one day, respectively. Clearly I did not gain 6lbs or lose 4lbs of fat in one day. It was just water retention. And it doesn’t end there: I’ve seen changes of +14lbs and -11lbs in the first 3 days of a drastic dietary change.
This means that, unless your diet is perfectly controlling for water retention levels and all its causal factors above, you will inevitably have a pretty large amount of noise in your experiment, concentrated at the beginning.
Think about it: we just said that losing 4-8lbs/mo is the minimum for a decent experiment.
If we ran the experiment and started it by gaining 6lbs of water, we could lose 6lbs of fat that month and not even notice! The scale would show zero change. Yet 6lbs of actual fat loss would probably be considered a huge success.
On the other hand, we could lose 6lbs of water weight in the first week and then not another pound the rest of the 30 days. This would make it look like we actually had great success and lost 6lbs of fat, yet we actually didn’t lose any fat at all.
This change in water retention and therefore water weight plateaus eventually after the dietary change is finished. For me, this is typically 3-5 days, depending on how drastic the change is.
You eat a high-carb, high-salt, high-fiber diet. You then switch to a low-carb, no-salt, low-fiber diet (say, keto or dirty carnivore).
You’ll probably lose at least 5lbs in the first 5 days after the transition, but after that, you wouldn’t see any additional changes in water weight.
This means you’d start seeing actual fat loss (as opposed to water weight loss) after about 5 days.
If you introduce the dietary change more slowly, it will take you longer to reach the plateau.
You eat a high-carb, high-salt, high-fiber diet. You begin slowly lowering your carb, salt, and fiber intake over the course of 2 weeks.
You will begin to see slow water retention changes even at the beginning, but will probably not reach the water retention plateau until 3-5 days after you finish the transition.
This means you’re seeing non-fat weight changes for 2-3 weeks. If your entire experiment only runs for 4 weeks, you’ll only have about 1 week of noise-free data on actual fat loss.
Worse, if you’re unaware of the water retention, you might think that you’ve discovered a great fat loss diet. Most people lost a lot of weight for 3 weeks straight!
Had you introduced the change quicker, or run the experiment for longer, you would’ve discovered that people reached a plateau quickly and there might've been no subsequent fat loss
This has an upside too: it means that if you go off your diet for a little, and you immediately gain 5lbs or more, that doesn’t matter much. It’s just fluctuation in water, and will come off within days after going back on a low-water-retention diet.
Side note: it’s not that water weight loss is bad. Being lighter still feels good, it makes you look slimmer, and it affects your clothes size. There’s no need to hold on to more water than necessary. But the water retention change will be a one-time plateau effect and you can’t keep dropping water to reach a normal weight.
Bonus side note: Reducing fiber drastically can lead to constipation. Reducing salt drastically can lead to headaches. So it can actually make sense to phase these in/out slowly, say 1-2 weeks, just to make the transition more pleasant.
All diets and diet studies should explicitly mention the water retention effects of the diet. Anything else is dishonest, selling water loss plateau effects as sustainable fat loss.
Delayed Caloric Bankruptcy means the Diet is Unsustainable, but you might not Notice
There’s another reason why I recommend you run a diet experiment for at least 30 days. Let’s coin this terrible term just because I don’t know a better one.
There is a pretty obvious feedback loop that regulates our food consumption and behavior as humans. The system is designed to roughly give us enough energy intake to do what we need to do all day.
If we require more energy, it causes us to eat more food. If we can’t find food, it’ll down-regulate major energy consuming systems and we’ll become lethargic, feel cold, sickly, we might lose muscle to use as energy. The symptoms we experience I’ll call “caloric deficit symptoms.”
We have a lot of slack in the system. If you don’t eat breakfast one day, you’re not going to die by lunchtime. In fact, most people could actually survive for weeks or months without food - if they were stranded on a lonely island. But it would not be optimal. They’d feel like crap much of the time, they wouldn’t be very happy or energetic, they might lose muscle and become weak and emaciated. That’s why you can’t just water fast your way to a six pack. (Trust me, I’ve tried several times.)
Generally, the body does not like to be in that state, and it’ll do almost anything to get you out of it.
Any diet that simply introduces an energy deficit into your life, be it by eating less or burning more, will eventually push you into “caloric bankruptcy.”
It might happen rapidly or slowly. If you just stopped eating today and did a water fast, you’d probably notice the symptoms within a few days. I’ve practiced fasting quite a bit, and I can usually go 2 full days without noticing anyting. But by the end of day 3, I am probably feeling cold, lethargic, can’t concentrate, will begin reading random articles about steak and watch YouTube videos about cooking steak and did I mention steak? This is my body trying to trick me into eating some steak so it can finally have some energy.
The thing is, every deficit-based diet will eventually lead you to caloric bankruptcy, it’s just a question of how long.
Water fasting is just a more intense version. While your body can downregulate energy-consuming systems, it obviously can’t go to zero. In my experience, as a 6’1 male, I can get down to roughly 800-1,200kcal and still function reliably over longer periods of time (say, weeks).
So within a few days on a water fast, my body will have downregulated to that level and since my intake is zero I’m now in a deficit of ~1,000kcal/day.
You could go on another diet that only introduces a 200kcal/day deficit. You’d still hit caloric bankruptcy, it’d just take you longer. I haven’t tested this exactly, but anecdotally it seems pretty linear, so we can probably just look at the area under the curve.
With a 200kcal/day deficit you can probably “make it” 5x as long as I can with a water fast. So you might make it 15 days instead of 3. Isn’t that great? You dieted for 15 days!
The goal isn’t to spend a lot of time “on a diet,” is it? The goal is to lose fat. Failing slowly isn’t more sustainable or more effective than failing fast when it comes to weight loss. The goal is to not fail!
If you’re introducing an energy deficit into your diet,
all you’re doing is fasting inefficiently. You could’ve gotten the
same result (failure) on day 3 of a water fast and have 12 days left to experiment.
Now the pernicious thing is that if you’re not aware of this inevitable result of caloric deficits, you might actually think the 200kcal deficit diet works.
After all, you lost weight for 3 weeks! And then, somehow, you couldn’t stick to it. Instead of blaming the diet for setting you up for failure, you might blame yourself, or curse your weak willpower. Depending on your deficit, you might not notice symptoms of caloric deprivation until 3-4 weeks in.
I’ve seen this time and time again with friends who tried this or that or anything and report “great success” for a week or two, or rarely, three. Then they stop mentioning the diet. When I inquire, they will inevitably mention how the diet actually worked great, but they just didn’t stick to it and they’ve gained all the (water) weight back already. They vow to try it again at some later time, and this time they’ll use all their willpower!
Yet the diet just delays their caloric bankruptcy, and it’s never going to work.
Run Experiments for 30 Days or More
Combining the effects of water retention and Delayed Caloric Deficit Bankruptcy, you can make almost any diet appear to “work” if you run it for short enough, ignore that the initial plateau effect is neither fat loss nor sustainable, and pretend people can run a caloric deficit forever.
This is the bizarre logic by which studies find that
"every diet works" yet practically no diet works in practice.
I've personally had caloric deficit symptoms not show up until day 16 of a 2,000kcal/day In'n'out burger diet. I’m not exactly sure what my deficit was on that, but if we go by area under the curve and compare with the 3-day water fast from earlier, it might’ve been something like the 200kcal/day.
Any study of less than ~3 weeks would've concluded this diet worked awesome, yet it wasn't sustainable. That became quite clear at the end of week 3 when I could barely concentrate on my job, felt cold in the summer heat, and couldn’t fall asleep at night. I quit very shortly after that.
Eye on the Long Term
Remember, if we’re going to go from some level of obesity to some level of normality, we’ll have to do this for probably 6-18 months, depending on our current and desired weight. E.g. for me, currently just below 250lbs, I’ll have to lose another 60lbs or so until I reach normal weight BMI at 188lbs. Even at 10lbs/mo, that’s another half year. And I’ve been doing this for nearly half a year already!
So let’s keep our eye on the ball. The goal is to find a diet that is sustainable for the entire 6-18 month period, not something that works for 2 weeks and then we crash & burn.
Any diet/regimen/intervention that produces "great results" in the short-term but doesn't sustain these results over a prolonged period of time is not a success.
Recap: Experiment For 30 Days
This will not guarantee success but probably filter out:
Short-term water retention effects that plateau within a few days
Delayed Caloric Bankruptcy that can take 2-3 weeks to materialize
Wow, that was a long section. Let’s get back to defining our successful diet.
What I mean by sustainable (as opposed to sustained) is:
No feeling of constant sacrifice and deprivation
No counting days until diet ends
No calorie deprivation symptoms
No craving other foods
Works in your day-to-day life, without extreme coercive measures/interventions
I’ve additionally included the word “effortless” in the definition. This is a bit more subjective, but highlights an important point: if you have to put too much effort into the diet, you will not succeed. A subjective feeling of effortlessness is a sign that the diet is working on a biochemical level, still providing enough energy for you day-to-day.
The brain is pretty good at giving us signals that we then misinterpret or brush off as mere “feelings.” If you hate your diet, you will not stick to it for 6-18 months.
Of course that doesn’t mean you should pick a diet of brownies and cheesecake, no matter how good it feels. You need to pick a diet that is effortless and makes you lose fat rapidly and sustainably, as discussed above.
Signs of Success
Here’s a list of success signs that I’ve personally experienced and heard from other people anecdotally when they finally found a diet that worked long-term for them.
Weight loss that is meaningful (4-8lbs+/mo) and sustained (>1mo)
Not shocking: a successful fat loss diet requires that you lose fat. Kind of in the name, isn’t it.
Running slightly cooler than normal (but not cold!)
Maybe you put on a jacket a bit earlier than usual. Maybe you feel less hot at the office than you’re used to. Your body might run a little bit cooler than usual.
But it should not feel uncomfortably cold! If you find yourself shivering, or putting on a jacket at unreasonably high temperatures, you might accidentally be in a caloric deficit. This will come back to haunt you via Caloric Bankruptcy, so don’t risk it. Say No To Deficits, Kids.
Feeling energetic, a spontaneous desire to be physically active. I typically get this when I finally “get into the groove” with a diet. It can take a few weeks or months to happen, and usually I’ll have lost 10-20lbs already.
I think this is basically the body providing a lot of energy and suggesting I get rid of it. On ex150 I began feeling the desire to take 45-60 minute walks after work about 2 months in. First occasionally. It quickly became a daily habit. Over the holidays, I found myself walking twice a day. Sometimes I’ll keep walking because I’m not “done” yet and I end up walking for 2 hours.
This is not me forcing myself to burn calories so I will lose weight. This is my biochemistry opening some sort of flood valve, providing a lot of energy for me to flare.
Generally good base mood, no lethargy. Mood is a pretty decent indicator of energy balance for me. When I’m lacking energy I feel like crap and just want to lie around. I can’t even read anything or focus on a movie. When there is plenty of energy available biochemically, I feel great for no reason and wake up with a smile. There is Joy in my life.
It's a good sign if you don't find yourself mentally focused on weight loss/dieting all day. I often forget I’m on the ex150 diet, meaning the energy balance is in check and I’m not energy deprived. Also way more pleasant than thinking about food and dieting all day.
BONUS: Being not eager/able to finish meals, despite trying. Often times on ex150 I will make a ~200ml bowl of whipped cream and only be able to finish half of it. I’ll put the remaining cream in the fridge. Luckily, it tastes even better the next morning! I don’t know how that works.
NO TRYING TO SNEAK IN A CALORIC DEFICIT. Don’t be that guy that pretends like he’s not hungry to prove the diet is working. This should happen to you when trying to eat. You should actually hit a feeling of deep satiety, not cut yourself short and take the shortcut to Caloric Bankruptcy. Treat satiety as a signal. If you try to push on it, it’ll stop working. The way I deal with this on ex150 is that when I don’t feel like eating any more whipped cream I force myself to eat another 3-5 spoons after 5 minutes. If I’m really satiated this will be painful. If it’s not, I’m not satiated yet.
Signs of Failure
No weight loss except small, temporary swings of a few pounds over 1-2 weeks.
If you’re not losing weight, it’s not a weight loss diet.
Plateau effect weight loss, which is mostly water weight. Disregard the first 3-5 days of rapid weight loss (with glee, but disregard it) and observe if there is further weight loss after that. It will be slower, but this will be fat you’re losing, not just water.
Your diet only works with extreme outside pressure, like being yelled at in bootcamp, being locked up in a nutrition ward, or going to some sort of rehab-style facility.
Unless you’ll be spending the next 6-18 months like this, you’ll need to find a diet that work intrinsically for you, not just under enormous pressure.
Plus, what after the 6-18 months? Are you just going to live in a nutrition ward from now on?
Calorie deprivation symptoms
Feeling "on edge"
Lethargy (this and adrenaline/on edge can flip flop back and forth)
Unable to concentrate
Illness (your immune system might be in energy saving mode)
Side note: should you get sick on a diet I recommend quitting the diet immediately and overeating (especially protein) for 2-3 days. Don’t restart the diet until you’re completely over the illness. Your immune system really can get pretty weak when you’re calorie deprived and I’ve had one of the worst viral infections of my life on a water fast. Not worth it.
Diet success means sustained, sustainable, effortless
weight loss of 4-8lbs/mo or more for at least 30 days leading to normal weight.
Almost everything else is a failure.
You now know what this means and why each individual element is important.
Going forward, you can evaluate every diet you do, your friends are doing, or that you see celebrities do, or even mentioned in studies, by these criteria. Does the signal beat the noise? Did the diet go long enough to filter out the water retention changes? And is there going to be Delayed Caloric Bankruptcy making the diet unsustainable?
May the experimental gods be with you and may your prayer be statistically significant.
Addendum: When 14 Day Experiments Are OK
I think 14 days are not enough to determine if a major dietary change will be successful. But it can be a long enough period for minor modifications.
You’re doing the ex150 diet and have been for 2 months. You’re seeing good success. Now you want to try an additional food. Say you want to replace the 150g of daily ground beef with 150g of deli meats like salami, roast beef, and turkey breast. This would enable you to more easily sustain the diet while traveling, where you’ll live in hotels and not have access to a kitchen every day.
It might be reasonable to substitute the deli meats for the ground beef for 14 days. Since the rest of the diet will stay the same and you’re only making a minor change, you probably won’t have to deal with huge water retention issues or sneaky caloric deficits. You might get a little less fat calories from the deli meats than you were from the ground beef, and so you might need to eat a little more cream to make up for it. But since the ex150 is ad libitum cream, that’s not a problem.
Fun fact: I’m doing this exact 14-day mod right now and I call it ex150deli. Stay tuned for the results.
Or you could do ABA diet breaks. Meaning two periods of being on the diet (A) are interrupted by one period of being off the diet (B).
You just did the ex150 diet for 30 days and you lost 8lbs. You also just moved to a new city, changed gyms, there was a cold snap, your boyfriend/girlfriend dumped you, and several other major life changes. This makes you unsure if the weight loss was due to ex150 or one of the other factors.
You could pause ex150 for 14 days. If one or more of the other factors were causing your weight loss, it should continue despite pausing the diet. If your weight plateaus or starts going back up a little, that is an indication that ex150 was the cause of your weight loss.
Unfortunately, this doesn’t prove that ex150 was the cause. You can thank the scientific method for that, only being able to disprove things, not prove them. Who made this thing?!
I think it’s still a great experiment-in-an-experiment. If you remember my graph from Losing 43lbs in 144 days, that’s exactly what I did late last year:
My weight initially went up rapidly (water weight gain), and then slowly (fat gain). When I went back on a low-salt, low-fiber, low-protein, low-carb diet (green shade) I initially lost the water weight very quickly, but then settled 2-4lbs above where I’d left off - this was likely actual fat gained in the 14 day period.
The 3 and 5 day breaks aren’t very demonstrative, as they were short enough to be almost entirely about water weight. You can see that the weight bounces back almost immediately.