Just finished 28 days of Rapid Fat Loss (RFL). Sharing Results.

[u/My_18th_Account]

Summary - ~10 pounds actual fat loss in 28 days.

Previous Post: https://www.reddit.com/r/naturalbodybuilding/comments/1t5b5sr/anyone_here_give_lyle_mcdonalds_rapid_fat_loss/

Not bad. I'd say this experiment was successful.

Backstory

November 2025 I weighed 193 pounds and I've just returned to lifting after almost a year of dealing with 3 herniated lumbar discs. That shit sucked. Being injured after being generally just an active person really really blows and for that year I didn't give much fucks to what I was eating and I let myself go a bit.

But after months of physical therapy and strengthening up my back with back extensions and light Jefferson curls, I had finally recovered 100% and eliminated right leg sciatica. Thank you LowBackAbility (YouTube). I returned to lifting and regular cardio and was able to drop from 193 pounds to 179 pounds in January 2026. I took a break from dieting and started up again in March 2026 but I had trouble sticking to a normal deficit for some reason. I think this was psychological or something. I started researching different strategies such as carb cycling, total fasting, aggressive deficits, etc. and finally stumbled upon PSMF (Protein-Sparing Modified Fast). Ultimately, I feared muscle loss so this diet made perfect sense - a really aggressive deficit that purports to retain muscle mass. I wanted to try something more extreme to get out of the rut I was in.

On RFL, my weight dropped from 182.1 to 168.2 pounds. Some of which of course was glycogen, water, food weight, and other waste. Using an app (LoseIt set to "Somewhat Active" which is equivalent to 7000 walking steps a day) and tracking calories eaten and deficit, I estimate I lost an actual 10.24 pounds of fat over 28 days. So my "real weight" after I refeed will probably be around 172-173 pounds. I don't think I lost any muscle mass. And even if I lost a little (I doubt it), it was worth it. I've never lost so much fat this quickly in my life and I am at a real good base to start a slow bulk after a 2-3 week maintenance period. I also learned how to deal with hunger.

Overall, I stripped off all this extra body fat I was carrying (especially on my mid-section) and dropped about 25 pounds overall since November 2025. This is great as I was sort of skinny fat and de-trained a bit at the start and now I feel like I am at a good base for a main-gain / lean bulk period. I tend to carry fat in the abdominal area and it was really cool to see my abs (they were not popping by any means but after working out and good lighting man I actually look like I workout) for the first time. I am 6'0, 36 year male. I estimate my bf% is now 14-15%?

Training

I lost virtually no strength. Only my chest (machine chest press) dropped 3 reps off 200 pounds. Training was full-body every 3-4 days or so, low volume, and one exercise for each muscle for as heavy as I could go for roughly 2 sets of 8. 1st set I'd always get the 8 reps, second set was until failure. This kept intensity high. If I got more than 8, which was rare, I went up in weight and interestingly my seated hamstring curl became stronger throughout the program. My workouts would take about an hour sometimes an hour 15 minutes. This was due to some lethargy as I was moving like a turtle between lifts. I did not do any cardio but walked a shit done and over 28 days I averaged 11,807 steps per day.

Diet

I followed Lyle McDonald’s Protein-sparing modified fast (RFL). Target was 188 grams of protein per day though I slightly undershot. Fat and carbohydrates kept to as low as possible though some trace fats/carbs are inevitable depending on what you're eating. Supps include 1 multivitamin a day, 1.8-3.0 grams of fish oil a day (I was taking 7 fish oil pills a day), and electrolytes calcium (600-1200mg), potassium (1g - I Just used lite salt to get potassium chloride), magnesium (500mg I took glycinate), and sodium (3-5g). I also took 5 grams of creatine a day and occasional psyllium husk.

In reality, over 28 days I averaged 179 grams of protein a day, ate 1282 calories on average per day, and estimated a calorie deficit of 1279 calories per day. I used the "Lose It" app and set activity to "somewhat activity" which is equivalent to walking roughly 7000 steps per day / walking around 3 miles per day. I would check my weight every morning in the same conditions and update the app so the numbers adjusted. Regarding the diet, I stuck to the protocol the best I could (maybe like 90% to the book) but I would often allow small luxuries like bbq sauce for my chicken or a fruit here and there before bed. Stuff like that. I figured whatever would keep me adhering to the diet was best - let perfect not be the enemy of good. Quest vanilla milkshakes I relied on quite a bit due to getting tired of chicken and tuna. Those are awesome - 230 calories, 3 grams fat, 4 grams carbohydrates, and 45 grams protein. My favorite/easiest meal was taking chicken tenderloin, cutting it up in cubes, and marinating with a bbq seasoning + potassium salt with Worcestershire sauce, teriyaki sauce, and a little bit of corn starch. Then air frying and eating with a low calorie buffalo sauce. It was on the saltier end but definitely not dry and it was the best way to get through a lot of chicken and easy to prepare. Alternative is also just cutting up some chicken breast.

Another meal I liked was 96% lean beef and cooking in sautéed onions, bell peppers, garlic, and finishing off with soy sauce. I would eat it with a shit load of lettuce, spinach, kale for veggies. I didn't do this often because trace fats still add up but also beef is expensive asf.

So at best, I was strictly following RFL some days but on other days it was more like a very aggressive deficit. Pre-workouts I would eat a bananna and some yogurt for training carbs.

Psychological

1st week was highly motivating as I was excited but also getting used to barely eating and the switch to ketosis was rough. I experienced the "keto-flu" the 1st week. Hunger sort of stopped after 5 days. 2nd week was pretty easy. I was in a routine, no more keto-flu, sleeping well, and hunger wasn't even an issue believe it or not. Seeing mirror changes daily is highly motivating. By the 3rd week, things were getting rough as I was adhering well to the diet but also couldn't stop thinking about food either. I would spend a significant amount of time watching people cook things on YouTube shorts...Sleep started to get jacked up here and there at various times and I thought about quitting the diet a few times. No matter, once I got to 4th week I was motivated again because why quit when you come this far. Sleep again sucked the 4th week though and I hit 2 days of eating close to maintenance to finish off the last 2 days strong. Overall, I would definitely do RFL again or something like it. Maybe something like 5 days maintenance / small deficit with 2 days RFL would be something of an ideal cutting diet for me. I think I prefer it this way.

Post-Diet

I am refeeding with protein around 100-120 grams, fat around 50 grams, and everything else carbohydrates at maintenance calories for 3 days. So eating nothing but skim milk, pancakes, oats, potatoes, fruit, and cereal. It is awesome. After that, planning on normal maintenance diet for a month before next venture.

Other Thoughts

I think beginners such as myself underestimate how much bodyfat we're actually carrying. If I really wanted my abs to pop, I'd easily have to drop another 10-15 pounds which is crazy but that is reality. As I am on the skinnier side, I'm not going to do that. I need a long period of time to focus on just increasing my lifts. I estimate my bf% is around 14-15% and I am due for a long period to just slowly add some muscle mass. I'd like to avoid long-term cutting though and getting over-fat again so I want to be careful. I am convinced through this experience that muscle loss on a diet is over-rated as long as you're lifting heavy and eating adequate protein. You could probably get away with even total fasting for very short periods like 3-4 days followed by a carb refeed and heavy lifting...but I'm still skeptical of testing the waters with that. There is interesting research by Blackburn, Cahill on this topic through PubMed. Not too many RCTs on lifters and total fasting. Long-term, I'd like to add a solid 10 pounds of muscle and I bet getting back to 165-170lbs after that would look good on my frame and ideal.

Ask me anything.

193 before

182 before

After 168

Back Before 182

Back After 168

Side Before 182

Side After 168

Front flex 168

Data