Many care facilities assume portion sizing for special diets follows the same rules as regular catering—but that's a dangerous misconception. Every gram matters with vulnerable clients, where overfeeding can trigger medical crises and underfeeding leads to rapid deterioration. You need precision-based calculations that account for each client's medical restrictions.
Why portion calculation in care is different
Care catering isn't about taste and costs alone. Every portion must align with the client's medical needs. Too much can be harmful, too little leads to malnutrition.
⚠️ Important:
Portion calculation in care is medical advice. Always work together with dietitians and doctors. These guidelines are general and don't replace professional advice.
Basic portion guidelines per target group
Different care groups have different needs:
- Elderly (65+): 1800-2200 kcal/day, smaller portions, more frequent
- Diabetes: Count carbohydrates, max 45-60g per main meal
- Kidney patients: Limited protein (0.6-0.8g per kg body weight)
- Heart disease: Max 2000mg sodium per day
Calculation per meal type
💡 Example: Diabetic lunch
For a diabetic patient weighing 70kg:
- Carbohydrates: max 50g (2 slices of bread + fruit)
- Protein: 25g (100g chicken or fish)
- Vegetables: unlimited (minimum 150g)
- Fats: 15g (1 tablespoon oil)
Total: approximately 400 kcal
Translating special dietary needs into portions
Gluten-free: Replace wheat with rice, quinoa or gluten-free pasta. Keep the same gram weights.
Low-salt (heart patients): Max 0.5g salt per portion. Use herbs and spices for flavor.
Protein-restricted (kidneys): Calculate exactly: body weight × 0.8g = daily protein requirement.
One of the most common blind spots in kitchen management is underestimating how quickly protein can accumulate throughout the day—even a slice of bread contains 3g protein that counts toward the daily limit.
💡 Example: Kidney patient 80kg
Maximum protein per day: 80kg × 0.8g = 64g
- Breakfast: 15g protein (1 egg + milk)
- Lunch: 20g protein (60g cheese)
- Dinner: 25g protein (80g meat/fish)
- Snack: 4g protein (crackers)
Total: 64g protein distributed throughout the day
Cost calculation for special diets
Special diet products often cost 20-50% more than standard ingredients. Factor this into your cost price:
- Gluten-free bread: €8/kg vs. €2/kg regular
- Lactose-free dairy: €1.50/liter vs. €1.00/liter
- Low-salt broth: €12/kg vs. €4/kg
💡 Cost price example:
Gluten-free lunch for 1 person:
- Gluten-free bread (80g): €0.64
- Topping (50g): €1.20
- Vegetables (100g): €0.80
- Special margarine: €0.40
Total cost price: €3.04 (vs. €2.20 standard)
Registration and control
Keep track of the following for each special diet portion:
- Exact gram weights of all ingredients
- Nutritional values per portion (kcal, protein, carbohydrates, fat, salt)
- Allergens and intolerances
- Date and time of preparation
Systems like KitchenNmbrs can help record this data per recipe and automatically calculate nutritional values.
How do you calculate portions for special diets? (step by step)
Gather medical information per client
Ask the dietitian or doctor for exact guidelines: how many kcal, protein, carbohydrates, salt per day? Which ingredients are forbidden? Create an overview per person.
Calculate daily distribution across meals
Divide the daily amounts across breakfast (25%), lunch (30%), dinner (35%) and snacks (10%). For diabetes: distribute carbohydrates equally across main meals.
Weigh all ingredients exactly
Use a digital kitchen scale (accurate to 1 gram). Record all weights and calculate nutritional values. Check for cross-contamination with allergens.
Check and document each portion
Compare the calculated portion with the medical guidelines. Note any deviations and the reason. Keep this data for at least 3 years for accountability.
✨ Pro tip
Audit your portion weights every 2 weeks by randomly checking 5 special diet meals during service. Staff tend to eyeball portions after a few months, but a 20g protein overage for kidney patients can cause serious complications.
Calculate this yourself?
In the KitchenNmbrs app you can do this in just a few clicks. 7 days free, no credit card.
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Frequently asked questions
Can I determine portions myself for diabetic patients?
No, always work together with a dietitian. You can prepare the portions according to their guidelines, but the medical responsibility lies with the care provider.
How do I prevent cross-contamination with allergens?
Use separate cutting boards, knives and pans for allergenic ingredients. Prepare these meals first, before regular catering. Wash thoroughly between different preparations.
What if a client doesn't eat the entire portion?
Record how much was eaten and report this to the care provider. If the client consistently eats too little, the portion size or menu needs to be adjusted.
📚 Sources consulted
- EU Verordening 852/2004 — Levensmiddelenhygiëne (2004) — Official source
- EU Verordening 853/2004 — Hygiënevoorschriften voor levensmiddelen van dierlijke oorsprong (2004) — Official source
- EU Verordening 1169/2011 — Voedselinformatie aan consumenten (2011) — Official source
- NVWA — Hygiënecode voor de horeca (2024) — Official source
- NVWA — Allergenen in voedsel (2024) — Official source
- Codex Alimentarius — International Food Standards (2024) — Official source
- FSA — Safer food, better business (HACCP) (2024) — Official source
- BVL — Lebensmittelhygiene (HACCP) (2024) — Official source
- Warenwetbesluit Bereiding en behandeling van levensmiddelen (2024) — Official source
- WHO — Foodborne diseases estimates (2024) — Official source
Food Standards Agency (FSA) — https://www.food.gov.uk
The HACCP standards shown in this application are for informational purposes only. KitchenNmbrs does not guarantee that displayed values are current or complete. Always consult the FSA or your local authority for the latest regulations.
Written by
Jeffrey Smit
Founder & CEO of KitchenNmbrs
Jeffrey Smit built KitchenNmbrs from 8 years of hands-on experience as kitchen manager at 1NUL8 Group in Rotterdam. His mission: give every restaurant owner control over food cost.
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