Portion Sizes: Separating Myth From Guidance

Weighing produces better data and worse adherence; hand-based portions scale with body size and work in restaurants.

Key takeaways

• Protein portion: 1 palm
• Vegetable portion: 1 or more fists
• Most useful single change: Fill half the plate with vegetables and fruit before serving anything else.
• Commonest mistake: Treating hand portions as precise; they are deliberately approximate.
• See a doctor if any of the signs under "When to speak to a doctor" below apply to you.

What the guidance actually says

Before the corrections, the published figures. Everything below is measured against these.

Where people go wrong

Common beliefs that the figures do not bear out.

• Treating hand portions as precise; they are deliberately approximate
• Cutting below the point where you can get through the day
• Using this method if you count carbohydrates for insulin dosing

What to do instead

• Fill half the plate with vegetables and fruit before serving anything else
• Adjust by one portion at a time and wait two weeks before judging
• Use the same method when eating out
• Add protein or vegetables rather than cutting further if you are constantly hungry

The part that is genuinely uncertain

Guidance changes, and it changes because evidence does. The figures above reflect current US guidance from the bodies named at the foot of this page; where those bodies revise their position, theirs is the account to follow rather than this one.

Related topics

• Reading the Nutrition Facts Label: What the Evidence Actually Says (Food Safety)
• The Evidence on Food Labels, Without the Hype (Nutrition)
• Reading Recipes Critically: What Published Guidance Supports (Healthy Recipes)
• Childhood Nutrition: Sorting the Evidence From the Noise (Children's Health)

Where to go next

• Your Questions About Portion Sizes, Answered
• The Short Guide to Portion Sizes
• Portion Sizes — the reference entry
• Weight Management: The Complete Guide
• The Evidence on Weight Fluctuation, Without the Hype
• The Evidence on Weight Maintenance, Without the Hype

When to speak to a doctor

Talk to your doctor or a registered dietitian rather than using general portion guidance if you have diabetes that requires carbohydrate counting, chronic kidney disease, or a history of an eating disorder, and stop and talk to your doctor if focusing on portions is making you anxious about food. If you have thoughts of harming yourself, call or text 988, and call 911 for fainting or chest pain.

Where this comes from

• USDA — MyPlate
• National Institute of Diabetes and Digestive and Kidney Diseases — Just Enough for You: About Food Portions

How this page was put together

Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarized or generalized beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.

Medical disclaimer

This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to your doctor, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 911.