Moussaka: frying the eggplant adds 111 calories a slice.

Classic vs lighter, per serving.

The same moussaka, 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. Use 95% lean beef, not ground lamb

−90 kcal, +3 g protein, −12 g fat, −5.0 g saturated fat a serving

The same 500 g saves 90 kcal and 5.0 g of saturated fat a slice, and adds 3 g of protein.

2. Roast the eggplant with 20 g of oil, not fry it in 120 g

−111 kcal, −12 g fat, −1.7 g saturated fat a serving

This is the largest swap in the pot. The eggplant soaks up the frying oil, and roasting saves 111 kcal a slice.

3. Make the béchamel with 1% milk

−11 kcal, +1 g carbs, −1 g fat, −0.8 g saturated fat a serving

The same 500 g of 1% milk saves 11 kcal and 0.8 g of saturated fat a slice.

4. Use 30 g of butter, not 80 g

−45 kcal, −6 g fat, −3.2 g saturated fat a serving

The roux needs less than you think. The extra 50 g was 45 kcal and 3.2 g of saturated fat a slice.

5. Top with 40 g of parmesan, not 80 g

−20 kcal, −2 g protein, −1 g carbs, −1 g fat, −0.8 g saturated fat a serving

A light dusting browns as well as a thick one. The other 40 g was 20 kcal a slice.

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

Moussaka is hard to estimate because it is three layers and the calories are in the two that look innocent: the oil the eggplant drinks and the béchamel on top. Building the tray as one recipe gives you a slice with all three layers in it.

What to weigh

Weigh the eggplant raw, before slicing, and the meat raw. The tray bakes down as the eggplant releases water, so the sample weighs 2,600 g from 2,958 g of ingredients and a slice is 325 g.

Tips while you build it

• Salt the slices for twenty minutes, pat them dry and roast them on a rack. They brown and soften without sitting in a pool of oil.
• 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.
• Rest the tray for fifteen minutes before cutting. A slice is about 325 g.

Go further

• Making the taverna version? Save a second recipe with ground lamb, 120 g of frying oil, whole milk and 80 g of butter.
• Serving it with a salad? Log the salad as its own food.

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