What is PSMF? All you need to know about the Protein Sparing Modified Fast
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As part of the Keto Mini Challenges in 2021 we decided to try PSMF. It has been gaining in popularity on Social Media and this blog post is intended to share everything you need to know to see if PSMF is right for you!
WHAT DOES PSMF STAND FOR?
In short: Protein Sparing Modified Fast
In a bit longer: “The concept of "protein-sparing modified fast" (PSMF) was described by George Blackburn in the early 1970s as an intensive weight-loss diet designed to mitigate the harms associated with protein-calorie malnutrition and nitrogen losses induced by either acute illness or hypocaloric diets in patients with obesity, in order to adapt the patient's metabolism sufficiently to use endogenous fat stores as well as to preserve the protein contained in the body cell mass.” (source Wikipedia)
Ok, there are a lot of big words here! Read on for the version that we can all understand!
WHAT IS PSMF?
PSMF is a high protein, low fat, low carb, low calorie way of eating!
When following a Keto diet and reducing carbohydrates you force your body into Ketosis which leads to burning fat for fuel. On PSMF you take it up another level and deprive your body of most fats in food and increase protein instead. This leads to your body burning BODY fat for fuel while maintaining muscle mass thanks to the extra protein! This combined with calorie restrictions can lead to rapid weight-loss.
WHAT ARE THE BENEFITS OF PSMF?
Protein Sparing Modified Fasts can help you rapidly lose weight and body fat. There are more benefits beyond that though.
Benefits you might see with PSMF:
Reduced insulin
Reduced hunger and cravings as your body moves into Ketosis thanks to the highly reduced carbs
Support with portion control in the future as you become more aware of portions and calories
Higher level of ketosis thanks to reduces carb intake
You do not have to be eating Keto or Low Carb to try this Fast. You might get more drastic results and you might need to drink a lot more fluids and keep electrolytes up if you’re transitioning from a regular diet to this temporarily.
Although these are all great benefits, there are also risks.
If you have any pre-existing conditions, make sure to consult a medical professional before trying this.
Going beyond 3 and especially 5 days can lead to nutrient deficiencies and more which should not be taken lightly.
WHAT TO EAT DURING PSMF?
Egg whites
Lean Poultry like Chicken or Turkey Breast
Lean Beef like Filet Mignon, Tenderloin, Skirt Steak, Heart, Liver, Flank Steak
Lean Pork like Tenderloin, Pork Chop with fat trimmed, Ham
FIsh like Salmon, tuna, tilapia
Seafood like Shrimp, crab or lobster
Low carb vegetables likes asparagus, zucchini, lettuce - most above ground are fine
Seasoning and spices - ideally without sugar
Low fat protein chips or puffs
This fast is a bit of “if it fits your macros”.
You could theoretically have some butter or olive oil if you can make it work in your calorie, fat and protein macros. You could also have some low carb fruit if this fits your macros. The above are foods you can eat in higher quantities given their nutritional make up.
More on how to calculate your macros in the next section.
If you stick to the above, you could be dairy free during this fast.
When it comes to fluids, you can have water, tea, coffee, electrolytes, low fat protein shakes.
PSMF CALCULATOR
This is the most complicated part of the Protein Sparing Modified Fast. Finding your own Macros. If you’re not sure what Macros are, check out the Keto 101 Guide.
Here are a few calculators I’ve used:
With Maria’s make sure to look at the PSMF macros that are shown second.
MY PSMF MACROS
I personally used all three calculators and then took the middle which placed me at the following Macros:
Calories: 750
Protein: 110g - Meet or exceed
Fat: 25g - Stay under
Carbs: 15g - Stay under
As you can see above, with Protein you’re going to want to meet or exceed that number. With Fat and Carbs you’ll want to stay under. Calories should be seen as a ballpark you’ll hit with those macros.
PSMF MEAL PLAN
I continued Intermittent Fasting while doing following this fast meaning I only eat between noon and 7pm. Here’s what my meals and snacks looked like while doing the Protein Sparing Modified Fast and insights and learnings to follow after!
Let me preface: I do not mind eating the same things over and over and over again during short fasts.
You’ll see this reflected below. I will include further meal ideas in the following section!
Day 1 - PSMF:
Lunch: Zucchini (4oz), Chicken Breast (10oz) and a Bag of Quest Nutrition Chili Lime Protein Chips
Dinner: Cucumber (4oz), Ribeye (6oz), Quest Vanilla Protein Powder Shake
Snacks: none
MACROS: Calories: 782, Protein: 131g, Fat: 22g, Total Carbs: 12g
Day 2 - PSMF:
Lunch: Cucumber (5.5oz), Chicken Breast (10oz), Bag of Quest Nutrition Chili Lime Protein Chips
Dinner: Lettuce (1 cup), Cucumber (4oz), Chicken Breast (3oz), Ribeye (2oz), Quest Vanilla Protein Powder Shake with 1.5 Strawberries cut and mixed in
Snacks: none
MACROS: Calories: 741, Protein: 131g, Fat: 17g, Total Carbs: 17g
Day 3 - PSMF:
Lunch: Zucchini (4oz), Chicken Breast (7oz), Bag of Quest Nutrition Chili Lime Protein Chips
Dinner: Cucumber (3.5oz), Chicken Breast (7oz), Quest Vanilla Protein Powder Shake with 1.5 Strawberries cut and mixed in
Snacks: none
MACROS: Calories: 763, Protein: 131g, Fat: 17g, Total Carbs: 14g
Transition out of PSMF
After 3 days I decided to start a slow transition out of PSMF. You’ll see those meals and macros below.
Day 4 - PSMF - Transition day:
Lunch: Asparagus (6oz) - I know! A different vegetable! I was excited too lol, Chicken Breast (8oz), Snack House Puffs Flaming Red Hot (0.4oz) and ChocZero White Chocolate Bunny (0.1 oz) - yep the tiniest bite
Dinner: Asparagus (3oz), Chicken Wings (8oz), ChocZero White Chocolate Bunny (0.5oz)
Snacks: none
MACROS: Calories: 993, Protein: 110g, Fat: 54g, Total Carbs: 18g
Day 5 - PSMF - Transition day:
Lunch: Asparagus (5oz), Chicken Wings (9oz)
Dinner: Zucchini (5oz), Ribeye (10oz), ChocZero Dark Chocolate Bunny (1oz), Enlightened Keto Butter Pecan Ice Cream (2.2oz) and Eat Different Keto Cookie Dough (1oz)
Snacks: none
MACROS: Calories: 1298, Protein: 104g, Fat: 83g, Total Carbs: 29g (18 net carbs)
During transition I like to introduce just 1-2 ‘new’ foods at a time to give my body time to adjust and in this case up calories a bit on the first transition day and more on the 2nd.
Wondering about cooking fats? Yep…I used none.
HOW TO COOK WITHOUT FAT
As I started planning my meals I quickly realized that I would need to find options to cook without fat if I wanted to keep my meat and veggie portions on the bigger side.
First day I tried cooking in the griddle and waffle maker which was a bit of a fail.
Day 2 I tried the grill - BIG WIN. And day 3 the air fryer - PERFECT.
I’m currently 2 weeks post this fast as I type this and I’ve stuck to using much less cooking fats and favoring the air fryer and grill over the pan. Especially the air fryer is magical because you don’t need to stand there and stir.
HOW DID PSMF WORK FOR ME AND OTHERS?
Similar to when I did my egg fast, carnivore fast and dairy free fast I tracked my weight while I was doing this. I did not track my level of Ketosis consistently but was glad to see on Day 3 that - unlike on carnivore - I wasn’t kicked out of Ketosis. My level was at 0.9 when I’m usually around 1.1-1.3 .
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Weight loss wise, the fast held up its end of the bargain. I lost over 6 lbs within a week. The first 3 days of those following the fast and the others slowly going back to normal. A few pounds are likely to be water weight as I had been hitting the Keto snacks hard prior to starting but the others I hope to keep off.
Sleep / Energy-wise I felt fine throughout. Digestion too. Nothing out of the ordinary. Mood was good too but I did feel like cognitively I wasn’t as on top of my game which mostly showed itself when working on my corporate day job and remembering all the daily life to do’s that creep up on me as a mom.
MY LEARNINGS WITH PSMF
After doing egg fasts, dairy free, a fat fast and carnivore, this fast seemed initially the toughest - so little calories? no cooking with fat? - and ended up being my favorite. Great results on the scale. Somehow I didn’t feel hungry. It helped me stop the snacking and I think my biggest factor in succeeding:
I chewed very very mindfully and slowly.
Although I had less food on my plate it took me longer to eat it and I think that significantly contributed to my success. Also during transition.
I also had the following learnings:
Track ahead of time: Enter what you plan to eat in a tracking app ahead of time to play with the macros and see how you can make it work on your low calories
Weigh your food: For this fast it was crucial to weigh foods to make sure I hit the macros and weigh your meat uncooked
Chicken Breast: According to my tracking app - MyFitnessPal - Chicken Breast has more fat than I thought! If I had had Seafood on hand I would have done that more to free up ‘fat-grams’ for butter
Snacks as part of meals: Eating Protein Chips was a great way to feel like you’re eating a lot without ‘using up’ a lot of my macros
Once again, Every BODY is different! Doing this with a group of people showed me how differently we all react. Most of us lost weight but not all. Most of us settled into this way of eating fairly quickly. But not all. Some of us tried super creative recipes while some - like me - just ate the same thing over and over and over. Listen to your body.
PSMF TESTIMONIALS
PSMF was part of a series of Mini Challenges I started on Instagram in which groups of people do these together, provide moral support and encouragement. Maria, also known as @thatketosis on Instagram approached this fast with much more creativity than me. She eats One Meal A Day (OMAD) and shared all her creations.
On day 1 she dug in to Sweet Thai Chili Shrimp Chicken Crust Pizza
On Day 2 she had Yellowfin Tuna Steak, Pan Seared Scallops and Egg White with Broccoli and Feta plus one of her famous coffee creations with Nut Pods, MCT Oil, Skinny Syrup and Collagen. See PSMF Day 2 on Instagram.
Day 3 was a composition of Broccoli & Feta, Egg Whites & Tajin, Buffalo Chicken Meatballs as well as a Snickerdoodle Keto Chow with Iced Coffee and Nut Pods. See PSMF Day 3 on Instagram.
Day 4 with Teriyaki Shrimp, Scallops, Garlic Rosemary Cauli Rice, Half a Fastful Bar and a Tea Latte with Nut Pods, Collagen AND… the PSMF Chocolate Pudding following Maria Emmerich’s recipe. That looked AMAZING. See PSMF Day 4 on Instagram
Day 5 with HighKey Protein Cereal and Cahew Milk as well as Cheese cruster broccoli & Feta Egg White Omelette and more pudding. See PSMF Day 5 on Instagram.
Day 6 was her final day with Turkey Burger with Provolone & Ranch on a SmartBun, Lemon Pepper Haddock Filet, Garlic Cauli Mashed, Dill Pickly, Cheeseburger Protein Puffs and a Cinnamon SmartCake. See PSMF Day 6 on Instagram.
Read on to hear from Maria!
PSMF Chocolate Pudding following the recipe of Maria Emmerich
“OK!! Let’s talk PSMF
I love the idea that this is a fast where you can still EAT!! Personally I aimed for 700cals, 25-35g fat and 95-105g protein daily. I found this was a great time to utilize seafood - shrimp was my go to protein. Overall, I was pleasantly surprised with how full and satisfied I felt on such a small amount of calories. Like other stricter styles of eating, I noticed my sugar and snack cravings decreased significantly.
Also shoutout to the sweet treat that came in CLUTCH when I did want that little after dinner treat - Maria Emmerich’s PSMF chocolate pudding. Made with hard boiled EGGS. This recipe is crazy good - trust the process 😉
In 6 days, I lost 6.2lbs. Not too shabby!! I can definitely see myself incorporating this style of fasting into my lifestyle to mix things up every now and then.”
It’s been amazing to do these fasts with like minded people and see how we all approach it differently, make it work and learn whether this is a good fit for us or not.
WOULD I DO PSMF AGAIN?
That would be a big YES. I think I’ll be doing this again 2-3x / year to reset habits and go clean Keto for a few days.
If you’d like support in trying something like PSMF, Keto or other types of fasts, check out my Personal Coaching!
Want to see what other fasts I’m exploring and how I’m staying Keto? Follow on Instagram. Especially stories where I share my day to day!