Lipoly

Your Fat Loss Sprint Guide

Optifast and the Fat Loss Sprint are both VLCDs. Here's the difference.

Both operate at a very low calorie intake with clinical evidence behind them. One uses meal replacement products. The other uses whole-food protein you choose, cook, and track. Different experience — same science.

How Each Approach Works

Optifast

Optifast is a clinically developed meal replacement program — shakes, soups, and bars formulated to provide complete nutrition at a very low calorie intake (typically around 800 kcal/day on a full replacement program). The convenience is the point: there is no food preparation, no macro calculation, and no food decisions to make. The products do the nutritional work.

Optifast programs are commonly run through pharmacies, doctors' offices, and weight management clinics. Medical supervision is often built into the program structure, which is a genuine benefit for people who want or need that oversight. Programs typically run 12 weeks on full meal replacement, followed by a reintroduction phase.

The Fat Loss Sprint

The Fat Loss Sprint operates at a comparable caloric range (800 kcal minimum, with the upper target calculated from your body composition) using whole-food protein — chicken, fish, egg whites, lean beef, cottage cheese — combined with unlimited non-starchy vegetables. There are no proprietary products. Your food comes from the supermarket; the app calculates your protein, fat, and calorie targets from your body composition. The AI meal planner lets you plan and verify meals in plain English so you hit those targets by design.

The protocol is 14–28 days, assigned based on your body fat percentage and sprint level. Resistance training (2x/week) is required throughout. Refeeds are scheduled automatically. A mandatory 14-day Maintenance Phase follows every sprint.

Side-by-Side: How They Differ

OptifastLipoly Fat Loss Sprint
**Food type**Meal replacement products — shakes, soups, barsWhole-food protein — chicken, fish, egg whites, lean beef, cottage cheese, vegetables
**Calorie range**~800 kcal/day (full replacement program)800–1,300+ kcal/day (calculated from your body composition)
**Protein basis**Complete nutrition via formulated product2.2–3.0 g/kg lean body mass — calculated from your body composition
**Food preparation**None — products are ready to consumeRequires cooking and food choices
**AI meal planner**Not required — products are pre-calculatedPlan meals in plain English to verify daily targets before eating
**Medical supervision**Often included — pharmacy or clinicSelf-directed app; consult your doctor
**Training component**Not specified2x/week structured strength training — required
**Refeeds**Varies by programScheduled mid-sprint and final day — protocol-defined
**Duration**Typically 12 weeks full replacement + reintroduction14–28 days sprint + mandatory 14-day Maintenance Phase
**Supplementation**Covered by product formulationSeparate: electrolytes, potassium, magnesium, vitamins
**Evidence base**Clinically developed; endorsed as VLCDPSMF: 50+ years, Harvard through *The Lancet*, 2014
**Cost**Varies by program and region; products plus supervision fees$9.99/wk · $29.99/mo · $149.99 lifetime

When Each Approach Fits

  • You want the simplicity of meal replacements — no food decisions or cooking required
  • You want built-in medical supervision as part of the program
  • You travel frequently or have a lifestyle where food preparation is difficult
  • You have previously found food-based restriction harder to adhere to than a replacement approach
  • Your doctor or pharmacy has recommended or supports Optifast specifically
  • You prefer eating real, whole food throughout the protocol
  • You want to develop the cooking habits and food knowledge that carry through to maintenance
  • You want your protein targets calculated from your specific body composition rather than a standard product formulation
  • You want a structured training component built into the protocol
  • You are looking for a shorter, defined sprint rather than a 12-week full replacement program

Both are clinically grounded VLCDs. The choice between them is largely about format preference and lifestyle fit — not about which one is scientifically superior. Discuss both with your doctor, particularly if you have pre-existing health conditions.

The Science Behind the Fat Loss Sprint

The Fat Loss Sprint is built on the Protein-Sparing Modified Fast — a clinical protocol developed at Harvard Medical School in the 1970s and used in obesity medicine for over 50 years. Key published findings:

**Purcell et al. (The Lancet Diabetes & Endocrinology, 2014):** 81% of participants on a rapid structured protocol achieved a clinically significant weight loss target — compared to 50% on a gradual approach. Dropout: 3% vs. 18%. Both approaches had identical long-term regain profiles.

**Longland et al. (AJCN, 2016):** High protein intake (2.4 g/kg/day) combined with resistance training at a 40% caloric deficit produced simultaneous fat loss and lean mass preservation. This is the evidence base for Lipoly's protein targets and mandatory training requirement.

**DiRECT Trial (Lean et al., The Lancet, 2018):** Structured very low calorie diet achieved type 2 diabetes remission in 46% of participants at 12 months.

668-patient PSMF case series: mean weight loss 18.6 kg; significant reductions in blood pressure and triglycerides.

Zero deaths documented in modern supervised PSMF protocols using complete protein and electrolyte supplementation (Seim & Flanagan, 1984; Wadden et al., 1990). Endorsed by NICE (UK), EASO, and AHA/ACC for appropriate candidates.

One Practical Difference Worth Noting

Optifast products cover electrolytes and micronutrients within the formulation. The Fat Loss Sprint requires separate supplementation — sodium, potassium, magnesium, and a standard multivitamin — taken daily throughout the sprint. This is specified in the app and is a non-negotiable part of the protocol; the 1970s safety events in early VLCD programs were attributed to electrolyte deficiency, not caloric restriction. Supplementation is the fix.

Same calorie range. Whole food. Your body composition in the targets.

Lipoly is a self-guided informational tool, not a medically supervised program. Consult your doctor before starting any VLCD — including both Optifast and the Fat Loss Sprint.

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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