Protein Sparing Modified Fast (PSMF)

## What it is PSMF is a short term, very low calorie approach built around lean protein intake to drive fat loss while protecting lean mass. For me, this is a tool, not a lifestyle or long term diet. ## How I am using it I am using PSMF 1 to 2 days per week during hybrid training. The goal is to drop body fat during half marathon training to enter my half as light and strong as possible, without sacrificing endurance, strength, or muscle. It's like a "mini-cut". Fat loss is structured around training, not through it. **My general rule that will not be broken is:** > Never starve training. I time PSMF after long run days, when glycogen demands are lowest and performance is not compromised. ## Calories and protein - 900 to 1,200 calories per day - 1 to 1.25 g protein per lb of lean body mass - Protein is the primary calorie source ## Macronutrients - Carbohydrates kept very low (30g or less) - Fat kept very low (30g or less) ## Scheduling For my schedule, Monday and Tuesday are optimal. **On PSMF days:** - No running - Walking is encouraged - Lifting is for maintenance, not growth - Yoga and mobility are fine ## Food choices Lean protein focused with minimal decision making: - Chicken breast - Shrimp - Egg whites - Pea protein isolate with cold water - Whey protein isolate with cold water - Bone broth - Cod, haddock (lean white fish) - Clams, oysters - 93/7 ground beef in limited amounts - Green vegetables  Fat and added carbohydrates are intentionally avoided. ## Important notes - This is an advanced tactic, not a beginner plan - Accurate calorie and macro tracking is required - Electrolytes matter - This should never precede hard training days ## Expected results Used 1 to 2 days per week, with the remainder of the week at maintenance or a slight deficit, this approach can realistically produce about 0.5 to 1.0 lb of fat loss per week while preserving training quality. Some will say to do this for a week or two. This is too long for me as it collides with physical objectives with demands for specific nutrition. Weekly calorie balance drives results, not individual days. ## Bottom line This is not about suffering. It is about precision. Fat loss is structured around training, not through it. Used correctly, PSMF is a powerful optimization tool for active adults who want to get leaner without breaking their training. **Lock in 2026 and optimize.**