Cooking for two: same pot, different goals

The idea: same ratio, different grams

When two people in a household want different amounts of food, the usual answer is two dinners or one compromise. There is a third option. A recipe is a fixed mixture, so every gram of it carries the same proportions of protein, carbohydrate and fat. Change the weight of the portion and you change the calories and the grams of each macro together, in proportion. The ratio stays put. The grams do not.

Where the two targets come from

Suppose two people sit down to the same pot. They do not need the same amount of energy, and a common starting point for estimating it is the Mifflin–St Jeor equation. For men it is 10 × weight in kg + 6.25 × height in cm − 5 × age + 5, and for women the last term is −161 (Mifflin et al., 1990). A systematic review of predictive equations found it predicted resting metabolic rate within 10 percent of the measured value in more people than the other commonly used equations (Frankenfield et al., 2005). “More people” still leaves some outside that band, which is why the result is an estimate.

Here are two made-up adults. Person A is a 35-year-old woman, 65 kg and 165 cm. Person B is a 38-year-old man, 85 kg and 180 cm.

• Person A: 10 × 65 + 6.25 × 165 − 5 × 35 − 161 = 650 + 1,031 − 175 − 161 ≈ 1,345 calories at rest.
• Person B: 10 × 85 + 6.25 × 180 − 5 × 38 + 5 = 850 + 1,125 − 190 + 5 = 1,790 calories at rest.

That is resting energy only. Activity, and whatever each person is aiming for, move the daily target from there, and that part is personal. For the rest of this example, assume each person has settled on a dinner target: 550 calories for A and 800 for B.

Splitting the pot

Take a chili that, per 100 g of finished dish, has 9 g protein, 11 g carbohydrate and 4 g fat. Using the 4/4/9 factors (21 CFR 101.9), that is 36 + 44 + 36 = 116 calories per 100 g, which is 31 percent protein, 38 percent carbohydrate and 31 percent fat. (The recipe is invented to make the arithmetic clean.) Each portion is the target calories divided by 116, times 100.

Cook 1,164 g of finished chili and the pot empties exactly. If you scale the recipe, scale every ingredient, and weigh the finished pot as we describe in the batch-cooking article.

When protein should not scale with calories

Calories scale with the portion. Protein may not need to. Sports nutrition position stands express protein per kilogram of body weight, with 1.4 to 2.0 g/kg/day as the range they call sufficient for most exercising people (ISSN position stand, 2017). For the two people above, that is 91 to 130 g a day for A and 119 to 170 g for B. A smaller portion may leave one person a little behind on protein even when the calories are right.

The easy fix is an add-on. Cook the shared pot, and give the person who needs more protein a measured extra, such as a side of plain cooked chicken, Greek yogurt or beans, weighed on the plate. The base stays shared and the difference is a few grams that you can write down.

Two cautions

• Goals are personal. This article is about arithmetic, not about what either person should aim for. If either of you has a medical condition, is pregnant, or has been given a plan by a clinician, use their numbers.
• Do not compare plates. A bigger portion is not more food in a moral sense. It is the same recipe, measured to a different target.

How we use this

The calculator on this site gives each person their own starting targets, and recipes in MacroCrafted are built from gram weights, so a portion is just a weight. Doing this for a household in one view, with separate profiles, is on our roadmap rather than a feature today.