Warsaw Method (FPU) Insulin Calculator
Estimate fat-protein units (FPU) and the extra extended insulin a high-fat, high-protein meal needs — on top of your normal carbohydrate bolus.
How to Use This Calculator
- Enter the fat in your meal in grams — read it from the nutrition label or a carb-counting app.
- Enter the protein in grams from the same source.
- Enter your insulin-to-carb ratio (ICR). Not sure of it? Estimate your ICR with the 500 Rule.
- Read the result: your fat-protein units (FPU), the carb-equivalent, the extra insulin, and the suggested extended-bolus duration.
The extended dose is given on top of your normal carbohydrate bolus — ideally as a pump's extended/square-wave bolus. Always agree the approach with your care team first.
How the Warsaw Method Works
Carbohydrate is not the only macronutrient that raises blood glucose. Large amounts of fat and protein also drive a slower, later glucose rise — often 3 to 6 hours after eating — which a standard carb-only bolus misses. The Warsaw Method, developed at the Children's Memorial Health Institute in Warsaw, Poland, quantifies that effect using fat-protein units (FPU).
One FPU is 100 kilocalories of fat and protein. Each FPU is dosed like 10 g of carbohydrate, using your own insulin-to-carb ratio — but delivered slowly so the insulin matches the delayed rise.
Worked example: a meal with 30 g fat and 40 g protein = (30 × 9) + (40 × 4) = 270 + 160 = 430 kcal → 430 ÷ 100 = 4.3 FPU. At an ICR of 1:10, that is 4.3 × 10 g = 43 g carb-equivalent ≈ 4.3 units of extended insulin.
How Long to Extend the Bolus
The more fat and protein, the later and longer the glucose rise — so the insulin is spread over a longer window (typically as a pump's extended or "square-wave" bolus):
| Fat-Protein Units | Suggested extended-bolus duration |
|---|---|
| 1 FPU | ~3 hours |
| 2 FPU | ~4 hours |
| 3 FPU | ~5 hours |
| 4 or more FPU | ~8 hours |
On injections (without a pump), some people split the dose or give a second injection later — this must be planned with your care team to avoid stacking and lows.
Which Foods Most Need Fat-Protein Dosing?
Fat-protein dosing matters most for meals that are high in fat or protein but low in carbohydrate, because a carb-only bolus barely covers them yet they still raise glucose for hours. Common culprits include:
- Pizza — the classic example; cheese and oil drive a long, late rise often peaking 4–6 hours later.
- Cheese, cream and full-fat dairy eaten in quantity.
- Fatty or processed meats — bacon, sausage, ribs, fried chicken.
- Nuts and nut butters, and rich desserts combining fat and protein.
- Low-carb, high-fat (keto-style) meals, where protein becomes the main glucose driver.
Light, mostly-carb meals rarely need it — a standard carbohydrate bolus is usually enough. The Warsaw Method is most useful when fat and protein clearly outweigh the carbs on the plate.
Frequently Asked Questions
What is the Warsaw Method?
The Warsaw Method is a carb-counting extension that doses insulin for fat and protein, not just carbohydrate. Fat and protein are converted into fat-protein units (FPU), and each FPU is treated like 10 g of carbohydrate, delivered over an extended period to match the delayed glucose rise.
How do you calculate a fat-protein unit (FPU)?
Multiply grams of fat by 9 and grams of protein by 4 (their calories), add them, and divide by 100. For example, 30 g fat and 40 g protein give (270 + 160) ÷ 100 = 4.3 FPU.
How much insulin does one FPU need?
One FPU is dosed like 10 g of carbohydrate using your own insulin-to-carb ratio. With a 1:10 ratio, one FPU needs about 1 unit. This is given on top of your carbohydrate bolus, spread over several hours.
Is the Warsaw Method safe to use on injections?
It was designed for insulin pumps, which can deliver an extended bolus. On injections it is harder and riskier because the dose can't be spread out, raising the chance of delayed hypoglycemia. Only attempt it with guidance from your diabetes care team.
Why does my blood sugar rise hours after a high-fat meal like pizza?
Fat slows digestion and, along with protein, triggers a slower glucose release that can peak 3–6 hours after eating — long after a carb-only bolus has worn off. That delayed rise is exactly what the Warsaw Method's extended fat-protein dose is designed to cover.
How is the Warsaw Method different from regular carb counting?
Carb counting doses insulin only for carbohydrate. The Warsaw Method adds a second dose for the fat and protein in a meal, converted into fat-protein units and delivered slowly. You still count carbs as usual — the FPU dose is an extra, extended layer on top.
Sources
- Pańkowska E, Błazik M. "Bolus calculator with nutrition database software: the Warsaw approach to insulin therapy." J Diabetes Sci Technol. 2010.
- Walsh J, Roberts R. Pumping Insulin. 5th ed. 2012.
Last reviewed: June 2025