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Draft: not yet reviewed by a clinician

Use this page to prepare questions for your care team. It does not replace their advice. Your own targets and doses come from your nephrologist, diabetes team and renal dietitian.

Portions

In short

Most kidney-diet problems are size problems. "A large amount of a low-potassium food can easily turn it into a high-potassium food" (NKF), and the same is true for phosphorus, sodium and carbohydrate. Learn a few standard portions, measure them for a week, and you will be able to judge them by eye at home and when eating out.

Your numbers: standard portions

Food Kidney-diet portion Looks about like
Fruit or vegetables ½ cup half a baseball (1 cup is a fist or a baseball)
Cooked meat, poultry or fish 3 oz (85 g) a deck of cards or the palm of your hand; fish fillet: a checkbook
Cheese 1 oz a pair of dice
Cooked rice, pasta or cereal ½ cup is about 22 g carbohydrate (white rice) a rounded handful or a tennis ball
Peanut butter 2 tbsp a ping-pong ball
Nuts ¼ cup a golf ball
Juice for a low 4 oz (½ cup) not "a glass"

Hand and object guides from MedlinePlus; kidney portions from NKF and NKF dining out. Hands differ in size: check your own hand against a measuring cup once.

Portion and serving are not the same. A portion is how much you choose to eat. A serving is the amount on the Nutrition Facts label, and the two often do not match (NIDDK); the label's serving may not match your kidney diet plan either (NKF label guide). If you eat two label servings, double every number, carbohydrate included.

What to do

  • Measure your dishes once. Fill your usual bowl, mug and glass with water from a measuring cup and write down what each holds. Many bowls hold more than one label serving.
  • Measure for one week. Use a measuring cup for starches, fruit and vegetables, and a kitchen scale for meat if you have one. After that, check yourself by eye and measure again now and then.
  • Serve on a smaller plate and put the extra away before you sit down.
  • Use your hand away from home. Meat the size of your palm, starch the size of your fist or less, and ask for a box at the start of a restaurant meal (Eating out).
  • Log what you really ate. In the app, pick the food, then change the number of servings or type the grams. The warnings and the meal's carbohydrate total change with the amount, before you save (app contract; Logging food).

Examples: when the portion changes the answer

Food Small portion Bigger portion
Cantaloupe ½ cup: about 210 mg potassium 1 cup: about 430 mg
Tomato 2 medium slices (¼ inch): about 95 mg potassium 1 whole tomato: 292 mg
Yogurt, plain low-fat ¼ cup is the portion 6-oz pot: 398 mg potassium, 245 mg phosphorus
Peanut butter 1 tbsp: about 90 mg potassium 2 tbsp: about 180 mg potassium, 107 mg phosphorus
Bagel ½ bagel is the portion whole bagel: about 420 mg sodium, 52 g carbohydrate
White rice ½ cup: about 22 g carbohydrate restaurant plate (2 cups): about 89 g
Restaurant protein 3 oz kidney portion 4–8 oz restaurant serving, 2–3 times as much (NKF)

USDA FoodData Central values through the app's food list (FDC).

A worked example. The label on a box of cereal says 1 cup is 25 g of carbohydrate and 30 mg sodium. Your bowl holds 2 cups when it is full. A full bowl is 50 g of carbohydrate and 60 mg sodium, plus the milk. If you measured 1 cup into the same bowl, it would look half empty, which is why the first week of measuring matters.

Ask your care team

  1. Which portions matter most for me: fruit, vegetables, meat or starch?
  2. How big should my meat portion be at lunch and dinner?
  3. Can you show me my portions on a plate at my next dietitian visit?
  4. How much carbohydrate should my usual bowl of cereal or rice have?

Get help now if…

  • Portions do not cause emergencies. If a large meal is followed by a low or a very high glucose with ketones, follow your plan; see Treating a low, Sick days and Get help now.

Sources

Not yet reviewed by a clinician. Facts and sources last checked 2026-10-06.