Complete PSMF diet guide – Rapid weight loss with a Protein-Sparing Modified Fast

Word of caution: The PSMF diet is not for everyone. It requires willpower like few other diets. But let me tell you that it works. It works very, very well.

What does PSMF mean? It is a shortening for Protein-Sparing Modified Fast, and it is probably among the fastest ways to lose weight while not completely compromising your health.

To achieve this, the diet attempts to combine the bare minimum nutrient requirements with the biggest caloric deficit possible.

What is a Protein-Sparing Modified Fast diet?

To answer that, we need to go back to the 1960s and 1970s, when experts and researchers in the health industry realized what appeared to be a growing trend in the US and the world: We were beginning to become fatter. And fast.


While it was not until the late 1970s and early 1980s before obesity rates really took off, the signs were becoming very clear in the decades after the second world war.

Plenty of “regular” diets and meal plans existed back then. Remember, the 1970s and 1980s were actually accompanied by a massive increase in the popularity of fitness and self-help.

Tons of diets came to be. Some of them ridiculous, some of them built on complete nonsense or even deceit. Either way, despite the 1970s wave of fashion fitness, obesity rates continued to climb.

On the lookout for more extreme measures, the 1970’s also saw some of the first commercialized crash diets. One now notorious diet from 1976 was The Last Chance Diet.

This insane diet had heavily obese people consume 300-400 calories via a special collagen, low-quality protein drink. The results? Some people lost a TON of weight – and some other people died as a result of the diet.

The protein intake was low, as was the nutritional quality of this specialized drink. It contained very few minerals and vitamins.

Nonetheless, The Last Chance Diet was a precursor to the PSMF diet framework we know and utilize today.

It helped establish the realization, that for some people, particularly the very overweight and obese, a tough crash diet could be seen as the only way out.

While it might sound harsh, we have to remember, that at certain levels of obesity which many people today fit into, health issues are numerous, and often life-threatening.

The modern PSMF diet is pretty damn safe

Fortunately, the crash diets of the 1970s and 1980s have come a long way, and the PSMF diets of today are by and large not unhealthy, as long as a few principles and rules are adhered to.

The main principle is the combination of enough nutrition to provide healthy bodily functions, and the biggest caloric deficit possible. It is the answer to the question; How low can we go calorie-wise, before adverse health issues might arise?

Luckily for us, we can actually go quite low. It is not uncommon for people to consume less than 800 calories. If you add lifting weights and/or cardio to that mix, you’ve got one hell of a ride. Well, diet. A tough one.

Basic PSMF diet principles


Consume chicken. Acquire six-pack. Straightforward.

One of the most important goals while losing weight is to simultaneously preserve muscle mass. This is something I have written more extensively about in my post Overweight? Lifting weights is crucial to your weight loss journey!

I suggest you check out that post if you want in-depth information, but to summarize: A combination of lifting and cardio is far superior to just cardio when dieting to lose weight – even if you are very overweight!

Anyways, to preserve muscle mass, we have two goals surpassing all else;

  • Consume a sufficient amount of high-quality protein
  • Follow a lifting routine

The PSMF diet acknowledges the importance of muscle retention, as it categorically singles out protein as the most important macronutrient.

In its most stripped-down form, a PSMF diet is all about consuming lean protein while cutting away almost all fat and carbohydrates from your intake. Chicken, lean fish, tuna, no-fat cheese, yogurt, etc.

Carbohydrate intake should ideally fall below 50 grams per day range, but going completely zero carbs is perfect. Fat on its own from fatty foods should be cut completely. Basically, the only fat to be consumed should be whatever amount of fat contained in your protein sources.

How much protein is dependent on your target, or ideal, body weight. The usual numbers were 0.5-0.7 grams of protein per pound of estimated lean body mass.

I find the protein recommendations in classic PSMF diets a little low, so without bringing up the good old calculator, my recommendation for most people will land between an intake of 150-200 grams of protein. The fatter you are, the less protein you will need, and vice versa.

Even at 180 grams of protein, we can hit less than 900 calories consumed. 800 even if you go for really lean sources, such as chicken breast.

This recommendation is somewhat in line with that given by Lyle McDonald in his book The Rapid Fat Loss Handbook, which in essence is a slightly modified PSMF diet. He also encourages the consumption of plenty of green leafy and fiber-rich vegetables, for added vitamin intake.

I can give my most sincere recommendation of that book. It was a game changer for me, which I will touch on later in this post.

Macronutrient guidelines summary;

  • Let protein dictate caloric intake ⇒ aiming for 150 grams per day will fit almost everybody, but bumping it up to 200 if you are decently lean already is fine.

  • Eliminate as many carbs as possible ⇒ Consume at max 50 grams per day.

  • Eliminate as much fat as possible ⇒ Only fat should be small amounts from the lean protein sources of your choice.

  • Consume plenty of green leafy vegetables, preferably the fibrous type.

  • Consider efficient supplementation. (Further info later in the post)

The biggest benefit of a PSMF diet


Supersonic dieting.

Now, even though a diet with so few fats and carbohydrates might not sound very sustainable, nor well thought of – there is plenty of reasoning behind the madness.

Let me get the first and perhaps biggest benefit of all out of the way: speed. The speed at which you lose weight is an incredibly motivating aspect of following a PSMF diet.

Advising people to follow a moderate, long-time sustainable diet with a cookie-cutter 500 calorie deficit is not bad at all. In fact, for most people, it’s probably the most advisable way to achieve a long-term lifestyle change.

But there is a caveat. People often fail at moderate diets with low-calorie deficits because they have a very thin and fine line between being in a caloric deficit and consuming maintenance or even a surplus of calories.

If your daily caloric deficit is only 400-500 calories, it doesn’t take too many errors during the day for that deficit to shrink and potentially vanish.

Especially not when we factor in everyday life, where our energy expenditure can vary greatly because of different work tasks, family business, anything really.

Now imagine being in a 1500 calorie deficit per day. You could mess up and consume a big-mac and you would still be in a sizable deficit and lose weight.


Hey, I never claimed I was any good at visual design. But this image visualizes the difference between a 700 calorie screw-up when following a regular diet, compared to a PSMF diet.

I often find that people I instruct on PSMF diets complain a lot during the first few weeks, but as they step on the scale and notice continuous weight loss like they have never experienced before – they suddenly gain additional willpower and determination.

This phenomenon is also found in the scientific literature, where PSMF diet studies can boast lower dropout rates (people quitting the study due to whatever reason: often an inability to comply with said diet).

Additional benefits of Protein-Sparing Modified Fast

Protein has the highest thermic effect of food. In layman’s terms, this means that our bodies spend more energy processing a gram of protein compared to a gram of fat or carbohydrate.

This also translates into a stronger feeling of satiety, as favoring protein intake above other macronutrients will generally result in a lower overall caloric intake.

  • Stronger thermic effect → Stronger feeling of satiety → Lower total intake

Additionally, a PSMF diet is surprisingly good at muscle sparing. Let me elaborate..

If you’ve been a part of the fitness and bodybuilding online community for a few years, you’ll have noticed how much people stress about muscle loss while dieting.

At the first sight of flat muscles and less energy in the gym, they will be tossed into an existential crisis,  fearing that they have thrown away years of hard earned muscle mass.

Have they actually lost muscle? Not likely.

The reduced carbohydrate, fat (and likely sodium) intake from their moderate dieting endeavor has resulted in less glycogen and intramuscular triglyceride being stored in their muscles.

They interpret this feeling of flatter muscles as actual muscle loss. In reality, they most likely have not lost any mass at all.

But that is for a moderate diet – what about a PSMF diet with a huge caloric deficit? Well, plenty of studies suggest that larger deficits don’t instantly wreck havoc on your muscle mass. The Minnesota Starvation Experiment is perhaps the most famous one.

Now, I know that some studies are conducted on not-so-muscular subjects, but we also have to factor in muscle memory.

Any muscle tissue you were to lose during a PSMF diet, would be right back on within a few weeks, maybe even less. And compared to a regular diet, you will be back to bulking up much quicker.

That is also part of my reasoning on why I swear by this type of dieting, even now when I constantly hover at around 10-12 % body fat. A bout of PSMF is just so much faster than regular dieting, resulting in me being back on the bulking or maintenance train much faster.

To summarize on this point; lift heavy and frequently and get your quality protein in – and most if not all of your precious muscle will survive just fine.

My experience with PSMF – +60 lbs lost in 8 months

As you probably know by now, I have a thing for this type of dieting. But it wasn’t always like that.

If you’ve read my post 5 tested tips on how to adhere to your diet   you will know a bit about my first major diet, but to sum it up i;

  • Was a big bulky teddybear at 235 lbs and 5’10.
  • Was decently strong, with among other lifts a 5 x 330 lbs bench press.
  • Was also pretty fat, much more than my delusional mind would accept.
  • Wanted to lose weight fast, as I had not been lean for more than 4 years at the time.
  • Adopted a PSMF style diet, stuck to it for the majority of (almost) 8 months, and lost 11 inches off my waist and just north of 60 lbs.
  • Retained 95 % of my strength. Actually slammed a personal record halfway through the process.

So yeah, it kicks ass, while kicking your ass. I pretty much had a full-blown affair with protein shakes and plain chicken. Consumed way too few vegetables and didn’t really bother with supplementation.

Looking back, there are a few things I would probably change, to make it all a bit easier.

Recommendations for a solid PSMF approach

Follow the protein, carb and fat guidelines summarized earlier in this post, but mix in some supplementation to ease the process. These recommendations are in line with those of Lyle McDonald.

In his book, he adds onto the core PSMF approach by suggesting a few supplements to be taken while enduring the diet. This is to counter what would otherwise be a quite vitamin and mineral poor diet.

I expect most of you already take Multivitamin and Fish oil supplementation, but I am listing them just in case.

Multivitamin – Added for obvious reasons.

I recommend these by Dr. Tobias. Good price and boasts more than 2150 customer reviews, averaging 4.6 out of 5 star ratings.

Electrolytes, sodium & potassium – Helps avoid fatigue

Cramps on super low carb diets are common, as well as stomach issues. Some people can counter this by utilizing a potassium salt, in fact, I did that for a short while during my own PSMF diet. I did have to consume a lot though.

If you want a hassle-free solution, these Hi-Lyte tablets include a good dose of magnesium, potassium, sodium, and zinc. They also boast 4.4 of 5 stars based on more than 665 customer reviews.



Adequate calcium intake can be very tough to achieve while doing a PSMF diet, especially if you don’t let dairy protein fill up in your daily protein goal.

A calcium supplement is an easy way of making sure you get enough. After researching the field, I found that not only are these funky looking gummies from Vitafusion very cheap, they also have 4.3 out of 5 stars with more than 1200 customer reviews. Good deal! Even if they look like candy!


Fish oil

Last but definitely not least, we got fish oil. The benefits provided by daily fish oil consumption are too many to list. I think a joke within the scientific community is asking what fish oil isn’t good for.

You’re likely to have a low or non-existent intake of Omega-3, EPA & DHA while following a PSMF diet, but even with that being said, I always recommend everyone to take a fish oil supplement unless they get good fatty fish several times a week.

If you manage to consume a lot of fatty fish while adhering to the PSMF guidelines, then, by all means, get your fish oil from that source. I personally find getting it from fatty fish hard though, as the whole point of PSMF is to cut fat and push caloric intake as low as possible.

Like in my post on high-frequency biceps training, the obvious recommendation from me is Uniqnutra Pharmaceutical Grade Fish Oil. 4.9 stars out of 5 as of writing this and a strong price tag. Hard to beat.


While not at all a necessity, I can’t tell you how much caffeine can help while enduring a diet like PSMF. Energy levels can dip really, really low.

Now, I get 50 % or more of my caffeine from coffee, as I usually consume many cups while dieting (even while not dieting.. #addiction).

But at times I have been very happy with supplementing caffeine tablets, especially 30 minutes or so before a workout. It, of course, helps that caffeine benefits are backed by a truckload of science, particularly as far as fat loss and increased energy expenditure goes!

For current market availability, there really isn’t a lot of difference between products. Caffeine is caffeine. No fluff.

I therefore recommend these pills by ProLab, as they have a 4.6 out of 5 star rating with more than 550 customer reviews and are among the cheapest to boot.

PSMF workout routines 

Should you train differently while following the diet? Perhaps. It depends on how you train while not dieting.

If you are following a very high volume routine, pushing in excess of 30 sets per muscle per week, I would suggest you cut down on that a little.

Your ability to recover from a high volume routine will likely diminish quite a bit when you switch to a PSMF diet.

How much volume you will have to cut is hard to tell, as one thing I have found is that there is a HUGE difference from person to person in how much workload they can handle on sub-1000 calories.

I myself had stints where I did 6-7 fullbody workouts in a week while following a strict PSMF 950-1100 calorie diet. I am not kidding. I just had to be very careful with auto-regulating the intensity, making sure not to push whenever I had the slightest feeling that that wasn’t a good idea.

In fact, I hit an all-time personal record in the flat dumbbell bench press during this stint of insanity, getting 13 repetitions with the clown-sized 115 lb dumbbells I have available.

Anyways, without further ado, here are my thoughts on different routines and how they fit into the wonderful world of low-calorie protein only dieting. Do note that  I don’t recommend specific exercises, only volume, and frequency.

Exercise selection is up to you. If you have been lifting for a while you probably have a decent idea of what works for you and what doesn’t work.

That being said, given how low a volume I suggest for PSMF, I really suggest you emphasize bigger compound’ish movements – squats, deadlifts/RDL’s, bench presses, overhead presses, chin/pull ups etc.

FULLBODY –  Most fullbody routines with a frequency of either 2 or 3 times a week will be a good fit. Start out with just 2-3 heavy sets of each exercise for the first week or two of PSMF, so you will be able to gauge how your body handles (or doesn’t handle..) the workload.

The benefit of fullbody routines during this diet is their “bang for the buck” nature. The routine encourages few, heavy compound movements and simplicity, and is well optimized for easily tracking your lifts and strength.

UPPER/LOWER – I feel an upper/lower split can also be utilized to great effect on this diet. Ideally with 2 upper and 2 lower sessions a week. You’ll be able to go a little higher on the volume here from the get-go, about 4 sets should be manageable for most people.

The benefit to this type of routine is the overall lower systemic stress. By having just leg or upper body compounds on a single day, fatigue will likely be easier to control as the central nervous system should be less affected.

PUSH/PULL/LEGS – I think this setup is the least ideal for the PSMF diet. As your body is split into 3 individual workouts, and you really want to at least achieve a frequency of twice-per-week for each muscle, you are forced to do 6 workouts in a week (push/pull/legs/push/pull/legs/off).

For many people, this will be too much unless they cut the volume and perhaps make other adjustments, such as cycling highly taxing exercises such as squats and deadlifts.

Coincidentally, this seems to be the most popular routine in the regular-Joe fitness world, and outside of crash dieting, I can understand why.

What about cardio?

Well, I say tread carefully. You are already tweaking your diet to create a massive caloric deficit – while simultaneously lifting hard to maintain muscle mass. Adding cardio to this mix can turn you into a broken, battered human pretty fast.

Personally, I did do a good amount of cardio on the PSMF diet, but I tried to place it on non-lifting days, and I stayed away from high-intensity cardio.

Instead, my favorite is incline treadmill walking for 45 to 90 minutes a few times a week.

I’ll usually do it first thing in the morning, with a few cups of coffee and/or a caffeine pill in me

I find this cardio setup efficient, as it gets my heart going while not being too taxing on my system.

Sample workout and nutrition


Female lifters are awesome.

I’ll finish off this piece with a sample of what I consider a solid day in the life of soul-drenching PSMF dieting.

Now, this type of dieting is really ideal for times where you don’t have to attend a 9 to 5 job, but since that’s not the reality for most of us, I’ll outline exactly such a day;

7:00 AM (07:00)   – Wake up. Drinks two large glasses of water, takes multivitamin, takes electrolytes, sodium & potassium.

7:30 AM (07:30) – Breakfast. Omelet of egg whites, fat-free cheese. Takes fish oil. Takes calcium (Approx 30 g protein)

9:00 AM (09:00) – Checks in at the office. Prepares to die on the inside in this corporate hellhole.

1:00 PM (13:00)  – Lunch. Eats prepacked chicken breast with veggies because the office cantina is a trainwreck of processed, fat, greasy food. (Approx 30 g protein)

6:30 PM (18:30) – Dinner. Eats either more chicken or lean beef or lean fish such as tuna, cod, lobster etc. Also eats veggies. Whoooo. Veggies… Also takes fish oil (Approx 40 g protein)

7:30 PM (19:30) – Workout. Does fullbody workout while contemplating life. 1 exercise for each muscle, 3 heavy sets.

8:45 PM (20:45) – Post-workout. Consumes protein shake (Approx 30 g protein)

10:30 PM (22:30) – Bedtime. Eats same as for dinner, though maybe a little less volume. Takes calcium (Approx 30-40 g protein)


  • If possible, I much prefer working out in the afternoon, before dinner. You can do early morning as well if you are a psychopath.
  • Protein shake is optional. Though easy and convenient. I recommend Optimum Nutrition Gold Standard 100 % Whey. Been around forever, almost 17.000 customer reviews with a stellar rating. Only 120 calories pr. serving, you can check it out here.
  • For the bedtime snack, attempt to reach 40 grams of protein, as recent science suggest making sure we consume a large amount of protein right before bed.

Additional guidelines:

Every 2 weeks (every week if you are below 15 % bodyfat), incorporate a re-feed day. This doesn’t equal eating whatever you want.

Emphasize high carbohydrate meals over high-fat meals, as the main benefit from this re-feed day is replenishing muscle glycogen stores and up-regulating some of the hormones and other biomechanisms which the PSMF diet is harsh on.

These include insulin, ghrelin, leptin as well as testosterone. So in reality, this day is much like all the other days in terms of intake – you still keep protein lean and high, keep fat low, but just hammer down a lot of carbohydrates as well.

I suggest a maximum surplus of 500 calories above maintenance levels.

Every 3 or 4 weeks, consider taking a half or a full week off from the diet, returning to more regular, but healthy eating habits. While I don’t personally do this, as I just want the process over with, some people might feel they need it.

The PSMF diet is harsh for extended periods of times – remember, it spawned from a category of diets meant as “last chance” interventions for heavily obese people.

While the modern versions with solid supplement and vegetable recommendations are quite safe, we are still putting our body through immense stress by robbing it of so much energy on a daily basis.

PSMF meals – yes, there are cookbooks! 

I know the outline I just provided sounds amazingly bland. So if you’re a foodie that loves to do magic in the kitchen, my suggested PSMF meals are probably not the most exciting for you.

Luckily, with any diet, there are cookbooks. And the same applies to the PSMF diet.

However, seeing as the diet is still relatively unknown, there’s only a few cookbooks within this niche. I have only been able to find two.

One of them is PSMF Meals: 36 deliciously high-protein, low-fat, low-carb recipes for the Protein-Sparing Modified Fast (quite the title!)

36 recipes sound like a pretty impressive amount when there’s a very limited selection of foods you can consume on the PSMF diet. More impressive is the fact that it apparently includes recipes for enchilada Suiza, tacos, and even lasagna.

The book is divided into categories based on nutritional strictness, such as the “STRICT” category, containing recipes with less than 5g of fat and carbs. So far, all customer reviews are extremely positive, albeit there aren’t many.

The other one is Protein Sparing Modified Fast Cookbook, containing 48 recipes and 2 weeks of meal plans and grocery lists. The recipes are categorized a bit differently, into for instance “Breakfast” and “Main dishes”.

The reviews of this book are a bit more mixed as you can see, with several customer complaints. I would recommend waiting a bit, to see whether additional reviews will even out the overall rating or not.

Summarizing all this PSMF nonsense

All in all, the PSMF diet is incredibly effective, while equally brutal for many of those who follow it.

And at the root of all this, there is a need for caution. Listen to your body and adjust accordingly. For a lot of people, more moderate diets work just fine. This is the extreme way.

For me though, I can’t help but love the extreme way. There are many aspects of life where we are not rewarded on a 1 to 1 scale for our efforts.

But as far as working out and dieting goes, it’s pretty close. That’s the feeling I get when utilizing a PSMF diet. I suffer more for an equally greater reward than if I suffered less.

Thanks for your time – feel free to share!

Post title image is by Christian Berns @

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