Lipoly

Your Fat Loss Sprint Guide

21 days. Calculated targets. A defined finish line — and then you're done.

Sprint Level 2 is the 21-day Fat Loss Sprint: the most commonly assigned protocol, built for moderate body fat percentages, with structured refeeds and mandatory recovery built in.

What Sprint Level 2 Is

Sprint Level 2 is assigned to individuals with moderate body fat (men 16–25% BF, women 25–35% BF). It is the most common sprint assignment across Lipoly users.

ParameterSprint Level 2
Sprint duration21 days
Protein target2.6 g/kg LBM (mid FLS range)
Fat27 g/day
Refeed timingDay 10 + final day (Day 21)
Refeed carbs5 g/kg LBM
Post-sprint recoveryMandatory 14-day Maintenance Phase

What to Expect in 21 Days

Glycogen and water depletion (2–4 kg rapid loss), transition to ketosis. Appetite suppression kicks in by day 3–4.

The most productive fat loss week. Ketosis stable, appetite manageable, mid-sprint refeed on Day 10 restores leptin and provides a psychological reset.

Fat loss continues. Hunger is typically lowest in week 3 — the body has fully adapted to fat oxidation. Final-day refeed marks the sprint end.

5–10 kg over 21 days at Sprint Level 2, depending on starting composition, sex, and adherence.

Why 21 Days Works — The Science

The 21-day window is not arbitrary. It covers the full arc of a structured PSMF sprint:

  • Days 1–3: Glycogen depletion and ketosis onset — the hardest phase
  • Days 4–10: Deep ketosis and active fat oxidation — the productive phase
  • Days 11–21: Sustained fat oxidation with mid-sprint refeed to prevent leptin crash and manage adaptation

The refeed on Day 10 is critical. Leptin levels fall during sustained restriction; a planned carbohydrate refeed restores them acutely, supporting thyroid function and managing appetite for the second half of the sprint (Byrne et al., 2018 — MATADOR study validates the restriction/recovery cycling principle).

The 3-Week Comparison

Generic 3-Week DietLipoly Sprint Level 2
ProteinGeneric or unspecified2.6 g/kg LBM — calculated from your lean body mass
CaloriesFixed generic (1,200 kcal etc.)Calculated individually from your body composition
RefeedNoneDay 10 (scheduled) + Day 21 (final)
Training"Exercise"2x/week structured strength + daily steps
RecoveryNone14-day mandatory Maintenance Phase
Science basisNonePurcell 2014 (81% vs. 50%); Palgi 1985; MATADOR 2018

Science Section

Purcell et al. (The Lancet, 2014): 81% of participants on a structured rapid weight loss protocol achieved a clinically significant fat loss target. 50% of the gradual group did — over three times the duration.

Palgi et al. (1985): In a 668-patient clinical PSMF case series, mean weight loss was 18.6 kg over 17 weeks. A proportionate 21-day sprint produces 5–10 kg of predominantly fat loss with high protein and resistance training.

3 weeks. Calculated targets. A real finish line.

See your numbers

Run the calculator on your own stats.

Sprint level, calculated macros, and a recommended duration — based on your body composition.

Sprint Level 1
Lean Body Mass: kg
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—g
Protein
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—g
Fat
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—g
Carbs
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Calories
Recommended:
Training
  • 2× strength training per week
  • 8–10K steps daily
  • No running or HIIT
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