What is PSMF? A Practical Guide to the Protein Sparing Modified Fast
The PSMF Diet or Protein sparing modified fast is a very low calorie, low carbohydrate and high protein diet designed for rapid weight loss without causing muscle loss.
It is a diet that mimics fasting in it’s results except that you are still eating food and you are ‘sparing’ your muscle. That’s why the long name! If you think of it as a low calorie, low fat, low carb diet, it’s easier to understand then.
What I didn’t know is that this low-calorie diet has been around since the 1970’s and is typically used in hospitals and other medically supervised settings particularly with obese patients before bariatric surgery. It is designed to reduce body fat quickly while maintaining lean body mass, in other words it ‘spares’ your muscle.
It is not a long term diet and anyone following this very low calorie diet for any length of time should be doing so under the supervision of healthcare providers. Even under medical supervision, obese patients are kept on the PSMF diet for only up to 6 months.
So why am I even talking about it then?
Because there is a safe way that we can make use of the protein sparing principles to accelerate fat loss or break a stall when doing Keto. My issue is that lately in the Keto space it has become the new buzz word and there is so much hype. I think people should have a little more information about it so they can use it correctly and safely to enhance their Keto results.
How to Safely Use the PSMF Diet Principles for Keto
I had heard of the PSMF diet from many sources in the keto space. Very few people ever mention that it’s a medical diet or give any caution about it. What I kept hearing is that it burns body fat rapidly and of course that is what we all want right?
And that is true, it does. I was stalled for 3 months, started doing some protein-sparing days and a couple weeks later I was down 9 pounds and my pants were noticeably loose.
While I was doing it, I read everything I could about it because I wanted to learn the principles behind it. Most people don’t do that and my concern is for people who see these results after a few days and decide to do it even more! Please don’t!
If you are currently doing a ketogenic diet of any kind, having stalls and weight loss plateaus is part of the process. Our bodies do need time to catch up and adjust to a new body weight low.
That said, I understand that when a weight loss stall drags on for weeks and then months, it’s frustrating! That is why I wrote this article on How to Break a Weight Loss Plateau.
The Protein-Sparing Modified Fast is another tool that if used correctly (and safely!) can help you kick start your weight loss again.
So how can we use protein-sparing modified fast principles as a tool to help us get through a plateau or even get us to our goal weight?
- Use a PSMF macro calculator to get an estimate of how many grams protein per day to eat. The calculator will also tell you calories, grams of fat and carbs as well. I used the PSMF calculator from Maria Emmerich’s site here to estimate mine.
- Follow these macros for a MAXIMUM of 3 days per week. Preferably alternating days rather than consecutive days. Do not be tempted to think that if 3 days a week helps your weight loss along then more will be better. No, more will not be better and you will just be doing a crash diet, not making a permanent lifestyle change.
- Keep in mind that this is a temporary diet. Once you are past your weight loss stall and things are moving again, reduce the frequency of PSMF days.
What Am I Eating on a Protein Sparing Modified Fast Day?
The best way for me to explain it to you is by sharing my own macros for a PSMF day and then share what I typically eat. I used the macro calculator and came up with these recommended macros. (Be sure to run your own because we are all different!)
My Macros: 900 Calories, Protein: at least 140 grams, Fat: Max 30 grams, Total Carbs: Max 20 grams
The most challenging part for me was to get my protein intake up to 140 grams of protein while keeping my fat intake at 30 grams or less. I sure wasn’t able to do this with my favorite foods of rib eye steak and air fried pork belly bites!
In order to get this much protein I had to change my protein sources on those PSMF days. I chose to do 3 PSMF days per week on Monday, Wednesday and Friday. This left me 4 days a week to eat my normal amounts and do a refeeding of fat!
Lean Meat Protein Sources for PSMF Days:
- Skinless white meat chicken breast or turkey
- Extra lean ground chicken and turkey
- Extra lean ground beef
- Egg Whites
- Fat free Greek yogurt
- Lean cuts of beef such as eye of round, top and bottom round, top sirloin
- Shrimp, scallops and crab
- White flesh fish like cod and halibut
- Pork tenderloin or loin chops
- canned tuna (in water)
I also found that I really needed to eat 3-4 times a day, not only to make it easier to get enough protein but also I was getting hungry sooner from the lower fat intake! On my regular keto days (on which I am 99% carnivore) I had fallen into a natural routine of intermittent fasting where I ate a meal of meat and eggs at around 10am and then a steak at 5pm and that was it. Not hungry!
But this was not the case on PSMF days. Here is a sample PSMF day (recipe links at bottom of article):
- Breakfast: 2 Turkey Feta Burgers or 1 turkey feta burger and 1 PSMF Cinnamon Bun
- Lunch: Chicken tenders or Shrimp with a fat free yogurt based dip
- Dinner: Lean beef or fish or ground turkey scrambled with egg whites
- Snack: PSMF cake or deli turkey slices
I had not counted my macros in a long time, so I also had to keep careful track on those 3 days a week to ensure that my protein grams were hitting the goal! It was challenging and I never once hit the target but still the weight just fell off. And I always had my favorite foods to look forward to the next day so it was very doable for me.
Meal prep was also key for me. During the first month where I did 3 PSMF days per week I did a meal prep of lean meats that I could just grab and go during the upcoming week.
You can watch one of my meal prep sessions here.
I also tried to make it fun by cooking up PSMF Diet recipes that I have shared on Youtube! If you think that PSMF days are nothing but egg white omelets and plain chicken breast, think again! Here are a few:
- PSMF Italian Egg White Bread
- PSMF Cinnamon Buns
- PSMF Pulled Pork Pizza
- PSMF Pasta Noodles
- PSMF Turkey Feta Burgers (my personal favorite!)
At this point in my rather lengthy dieting career (yup I’m calling it a career now!) I have lost a total of 130 pounds. That is a significant weight loss and I’m grateful for every pound of it! But each pound is getting harder and I am still 40 pounds overweight.
So I am safely and carefully using the PSMF principles as a tool to help me get closer to where I want to be. By only doing the PSMF days up to 3 times per week I feel that I am doing this in a good way and avoiding any possible nutritional deficiencies or side effects.
I will be coming back to this post to update how I did in my second month and beyond.
Final Cautions Before Doing PSMF
- Do not follow the PSMF diet 7 days a week. Three days a week max is safe to do, the other 4 days will act like a refeeding phase to keep you not only satiated but sane!
- Watch for side effects like headaches and nausea. You may need electrolytes and minerals. Try my DIY Electrolyte drink here.
- Self check for signs of former addictive behavior coming back. I’ve seen it in facebook groups and myself! Watch yourself to not become overly obsessive with scale numbers and macros. If you are freaking out because you didn’t eat all your protein grams and went over on the fat grams, take a deep breath and have some bacon. And that is no joke! My first week (before I researched all this) I did a rotation of 2 days on PSMF and 1 day off and that was a mistake. I felt snakey and insane. Getting enough fat is very calming to me apparently! That week made me appreciate a simple steak.
- DO NOT do PSMF without checking with your doctor if you have any medical conditions you are being treated for (kidney disease, cancer, high blood pressure, etc). This is not the time to tax your body. Stay clean keto or carnivore for now. Same if you are pregnant or nursing, your baby needs the nutrients!
- Follow people who know what they are talking about when it comes to PSMF and don’t treat it like the latest greatest crash diet to solve all your problems. People who stay calm and treat this with respect, not hype. See my resources below.
Further PSMF Resources
The Keto Naturopath (this link is to a podcast about PSMF)
The Keto Naturopath Youtube Channel (they have recipes and good science based info)
Maria Emmerich (video What is a Protein Sparing Modified Fast?)
Save this PSMF Information to Pinterest!
30 thoughts on “What is the PSMF Diet? A Practical Guide to the Protein Sparing Modified Fast”
Besides that fat free Greek yogurt, how else can one add moisture to this diet? I can’t choke down the PSMF egg white bread that’s so popular and I’ve already been eating plain chicken and lean steaks, and it’s all so boring that I veer off low carb as it is. I’m very desperate, but at this moment, too fatigued to go into more details.
I appreciate your videos on YouTube and watch often, as I enjoy cooking videos, even if I don’t actually make most of what I see (I’m annoying finicky). I enjoy your personality too.
I hear you on this, lean PSMF days are not easy and it’s easy to get discouraged. Have you tried my Turkey burgers? Those are one of my favorites and the little bit of feta cheese in them does not add too much fat but does add moisture! Also with the PSMF bread, it goes down way easier if you throw in a couple of egg yolks at the end, it is softer. The other bread that helps is the Italian bread with the added bone broth powder. Somehow that makes it softer as well! Lean meats are way more juicy and tender if you have a sous vide wand, not sure if that is an option for you. And sometimes a person just has to take a break from PSMF and stick to Keto for awhile. I am taking the summer off to stay Keto, enjoy some summer Keto ice cream and go on holidays! In September I will be back with some new recipes, new videos for what I eat in a day of PSMF! But I need this break first to gear myself for up for it! PSMF is definitely a good way to get those last pounds off, and I want to ready mentally for this challenge! Hope you will join me in that!
I’m planning on a couple of cups of chicken broth on psmf days so maybe make a couple meals a chicken soup to add in some moisture. You could maybe make some psmf bread croutons or just crust the bread a little and dip it or maybe even like a French dip sub idea….btw I love your channel and recipes. I found you about a year ago and watch faithfully. You’re awesome!
Thanks so much, those are good ideas to help make things easier for people!
Is there any good info or thoughts on doing PSMF meals as opposed to days? So for example: being ketovore for many years I naturally eat lunch and dinner 99% of the time, no other meals. What are the thoughts on eating PSMF lunch for example at half the macros of a PSMF day and regular dinner? And doing this for 5 days a week. Meaning in total you get 5 meals of PSMF (2.5 days) and the rest regular ketovore?
Any reason it had to be the whole day? Would it present any issues?
I am experimenting with it right now – mostly because the dinner is difficult for me to make PSMF. Would that work? Or I am wasting my time?
Hi! I have not heard of people doing that but I like the idea! I would love to see how you make out! I honestly don’t see it as a waste of time, you are still doing keto or ketovore, you are still tweaking your macros to get results, cannot be anything wrong with that! It’s not one day of eating that will give you success it’s days strung together that add up. I think it’s worth trying! Please report back!
Thanks for the info, I think this is exactly what I need for a jump start, as I have been struggling on keto. I use Carb Manager, which I find helpful for tracking. I am finding it hard to get enough protein without going over on fat, calories and carbs. Can I count in protein powder? I add collagen peptides to my morning coffee, and do a low cal, high protein shake in the afternoon.
Yes for sure, count everything! The collagen, protein shakes etc do help to up your protein. If you go onto youtube, I do have some ‘What I Eat in a Day on PSMF’ videos. It can help you see what a day might look like. I find if I don’t use carb manager I will end up short on my protein and high on the fats and carbs. So good idea to track the PSMF days even if you don’t track the regular keto keto days. https://www.youtube.com/watch?v=kdeURMMHkZk&list=PLcnK_MiscYLLxwPSO2lzOz9jYoA3M7Rj5
Thank you! I will check out the link, and will be following you in the future!
Ok, hope it helps!
I hope it’s not too late to ask a question. I noticed that Maria Emmerich recommended an overfeeding day once a week. Did you every do that? If not, do you think it’s necessary or just on occasion, once a week at most, if you’re feeling particularly hungry that day?
It’s never too late to ask a question! I think this is a personal thing. For the same reason that I cannot ever have a weekly cheat day, an ‘overfeeding day’ is also tricky for me personally. I think some people can handle it and can benefit from it, but some people are also triggered by food amounts as well as too many carbs. So it’s a case of knowing yourself! If I am particularly hungry I just go for more protein in the form of meat or bacon or eggs.
Hello, thank you for all your good information and videos! I have a question for which I haven’t find an answer yet, ok I went and used the macro calculator, and my PSMF macros are 838 Calories, Proteins 132 grams, Fats: 30 grams, Total Carbs: 10 grams. How am I supposed to know how many grams of meat/egg whites/fish to eat, how many grams of fat, how many grams of vegetables or carbs? All of you seem to know, but I really don’t. Thank you
I think you pretty much answered the question right here! The answer is that on PSMF days you eat 30 grams of fats, 10 grams of total carbs in the way of veggies and other carbs and 132 grams of protein in the way of meat/fish/eggs, etc. Maybe you are asking how much weighed protein makes up these 132 grams? I would get a free account with carbmanager or myfitnesspal and check all your favorite foods in there. For example 1 whole large egg is aproxximately 70 calories, 5 grams of fat, 7 grams of protein and 0.6 grams of carbs. 3.5 ounces of skinless chicken breast is 175 calories, 0 carbs, 31 grams of protein, 4.5 grams of fat. These are things you need to keep track of while you learn what food has what macros. Hope that helps!
Thank you Keto Woman, I’m in! Congrats on your success. I see my new primary doc today so I hope she is on board. I’ve been mostly keto since the Atkins days, mostly carnivore for the past six months and mostly Intermittent Fasting with Jason Fung, MD guidelines for the past two years. Down to that last 30 lbs or so and have been stuck for 6 months.
This is a perfect way to get unstuck! Best of luck to you getting to the goal line!
So nice to “see” you here Nolu! I trust all is well with you and your journey for better health and wellness.
What is the procedure for when you are done with the diet? How easy is it to transfer to maintenance from this way of eating?
It would then just be a matter of adjusting your macros a little every week until you find that sweet spot where you can increase fat and carbs a little to see where you stabilize.
I’m really glad for all those who lost weight. I’ve been trying to do low carb since April 2004 and I just can’t stick with it. The longest I’ve gone is 21 days, and that’s way back then. Now I can’t even make it 2 days. So hungry, the food is so unsatisfying, and due to my born with it health condition of fatigue, I often can’t cook. I did a keto egg fast, but I ate more than is recommended, but it was still going good, but yet again, it got too boring and I then spin wildly out of control. It’s great to hear so many people are doing great but it’s also defeating and people have no compassion for someone who can’t do it because so many others can do it.
Have you ever considered trying carnivore? Very little cooking and food decision making, eat until satisfied and no counting of macros. I highly recommend watching the youtube channel called Zero Carb Life. You can also get some basic info from what I wrote here: https://ketogenicwoman.com/zero-carb-diet-plan-my-first-30-days/
There are compassionate people out there! Take care and don’t give up.
I’ve been keto since 2017. I lost 60 pounds and gained back 40. Having trouble losing again. I tried everything! Seems like the second time around is harder. I’ve decided to research PSMF again and found your article! So informative and inspiring! I’ve decided to try it! Thank you for all the information and your experience with this WOE. I know I’m not alone.
oh no, you are definitely not alone! I can’t even say how many times I have backslided, it’s been a long journey of 1 step forward, 2 steps back but I’ve managed to accumulate 135 pounds lost so far. Just stay with it!
Hi considering doing this psmd, how has it worked for you? How long did you do it?
I’ve also done keto since 2017/18 and I have stalled and tried everything. Ughhh so hard.
So happy to have found this article and your YouTube channel! I’m you at the start of the journey – need to lose 170lbs and I’m 63 so watching someone in their 30’s doesn’t help. Don’t need to try PSMF yet, but when I stall I know where to come for help. Thank you!
We are the same age! I have so far lost 130 ish pounds with a good 40 more to go, so we will have both lost the same at the end of this journey too! Everyone has to start somewhere, congrats for starting!
Me too, another senior here :o)! I’m 64!I need to lose 100 pounds- I’ve lost over 50. We can do this! Anita’s wealth of information has truly boosted my support and weight loss- I am refreshed and renewed!
So happy to read this!
Do you need to supplement your vitamins and minerals on a carnvore diet?
I don’t do it personally but that doesn’t mean that you don’t need to! I’m not a doctor or anything like that so can’t say. My own doctor has told me to supplement Vitamin D and I bought some but keep forgetting to take it!