Lasagna: four swaps, 135 calories off every square.

Classic vs lighter, per serving.

The same lasagna, made two ways from the same library entries and the same 8 servings. The lighter version is the one built on the screens below.

Saturated fat comes from the same USDA entries; the recipe sheet itself shows calories, protein, carbs and fat. Calorie and macro figures are fitness estimates, not medical or dietary advice.

Swap by swap.

Each change in turn, from the classic to the lighter version, and what it does to one serving.

1. Buy 95% lean beef, not 80/20

−58 kcal, +2 g protein, −7 g fat, −2.7 g saturated fat a serving

Same 400 g, 58 kcal and 7 g of fat less a square, and 2 g more protein.

2. Use Italian-style turkey sausage, not pork

−34 kcal, +2 g protein, +4 g carbs, −7 g fat, −2.5 g saturated fat a serving

Same 250 g with the flavour of fennel and pepper: 34 kcal and 2.5 g of saturated fat less a square.

3. Layer part-skim ricotta

−6 kcal, +3 g protein, −1 g carbs, −1 g fat, −0.8 g saturated fat a serving

The same 450 g of part-skim ricotta saves 6 kcal and 0.8 g of saturated fat a square, and adds 3 g of protein.

4. Top with part-skim mozzarella

−20 kcal, −3 g fat, −1.7 g saturated fat a serving

The same 250 g of part-skim mozzarella saves 20 kcal and 1.7 g of saturated fat a square.

5. Use 15 g of oil, not 30 g

−17 kcal, −2 g fat, −0.3 g saturated fat a serving

The meat sheds its own fat. The extra spoon was 17 kcal a square.

Ground meat: read the lean percentage, not the animal.

The number on the pack moves the calories more than the animal does. A 96/4 pack sits between the 95% and 97% entries: choose the closer one, or scan the barcode.

Oil and fat: the type changes the fat, the amount changes the calories.

The three oils below are each 884 kcal per 100 g, and ghee is within a few calories of them. Swapping one for another moves the saturated fat, not the calories; using less is what saves them. Butter is lower per gram only because part of it is water.

The sample data

These are the amounts of the lighter version used on the screens below, with each figure taken from the library entry for that ingredient. They are sample figures for a pot or tray of this size, not a measurement of anyone's kitchen.

Calorie and macro figures are fitness estimates, not medical or dietary advice. Ingredient values are from USDA FoodData Central, which is in the public domain.

Why this recipe

Lasagna is hard to estimate because every layer is a different food. Building it as one recipe gives you a square that already includes the pasta, the meat and both cheeses, and shows which layer the calories actually come from.

What to weigh

Weigh the noodles dry and the meat raw. The tray bakes down as the noodles take up water and the meat sheds fat, so the sample weighs 2,500 g from 2,806 g of ingredients and a square is 313 g.

Tips while you build it

• Read the lean percentage on the pack and pick the library entry that matches. A 96/4 pack sits between the 95% and 97% entries; choose the closer one, or scan its barcode.
• Drain the ricotta in a sieve for twenty minutes so the layers hold. Part-skim ricotta firms up well once the egg is in.
• Rest the tray for fifteen minutes before cutting. A square is about 313 g, and a steady square weighs the same each time.

Go further

• Making the family-recipe version? Save a second recipe with 80/20 beef, pork sausage, whole-milk ricotta and mozzarella, and log whichever one you baked.
• Serving it with garlic bread or salad? Log those as separate foods.

Each change is a second recipe with its own name, so the first stays as you built it.