serving sizes

Portion-Control: How to Eyeball Serving Sizes

December 21, 2020

First, let us work through the who, what, where, when, and why of serving sizes:

How to Determine Serving Sizes

Who actually eats the serving described on the nutrition facts label?
It is rare that a person reads every nutrition facts label and counts out or measures the serving size.  I remember completing my first college assignment in nutrition 101. We kept a detailed food log with exact portions for every item we consumed. I think that is the last time I actually measured and weighed every item that went into my mouth.

What is a serving size and how do you know if you are eating the correct serving size?
A serving size is described as,  “A standardized amount of food. It may be used to quantify recommended amounts, as is the case with MyPlate food groups, or represent quantities that people typically consume on a Nutrition Facts label” (1)  This differs from a portion size, which is simply the amount of food you eat at any given time. You can also use the Bariatric Food Pyramid for an overview of the recommendations for post-ops.

Each food group has a recommended number of servings per day. A dietitian can help you determine the appropriate servings for your age, activity, and health goals.

Where can I find out the correct serving size for foods without a label, like produce or prepared foods?
Many of the foods we eat come in packages with the nutrition facts panel. This will tell you what is considering one serving and how many servings are in the package. Produce, meats, and restaurant meals do not come with labels, but you can find recommended serving sizes at any of the following websites:

When is the last time I actually saw a deck of cards at the same time I was preparing dinner so that I could serve myself a piece of chicken the same size as the cards?  Ummmmm – never.

Why are we talking about this?
You have likely read articles and seen news stories about the growing portion sizes at many restaurants and the expansion of America’s waist size. 

When we choose a meal, or sit down to a plate of food, open a bag of chips, or put a fork into a box of takeout; we rarely take time to consider what amount of that food to consume – we just eat it.  We were trained as children to eat what is on our plate. But, a healthy and recommended serving and the amount served do not often match.

Fad Diets Lack of Appropriate Info

So many fad diets highlight the ‘right’ foods and villainize the ‘wrong’ foods without teaching appropriate servings.  Knowing recommended serving sizes could help you reach your health and weight goals while eating foods from every food group.

So now we know what a serving size is and why they exist, but how can you monitor your serving sizes in the real world?  

For many years dietitians, doctors, and websites have referenced tubes of lipstick for the correct serving of cheese, or a deck of cards for 3oz of meat, and tennis balls for apples.  This is all great but we rarely have those things within sight at meal or snack time. If you want to ‘eyeball’ your servings you have to develop the skill. 

  • Start measuring out your cereal according to the serving size listed on the nutrition label. 
  • Buy a food scale (it will help in cooking and baking too) and weigh out your meat before and after you eat it.
  • Use your measuring cups for cut fruit and cooked vegetables.

While you do all these things, pay attention to where they land on your plate. Do you have bowls with a pattern on them?  When you pour in your 3/4c of cereal (as an example), where does it land – on the blue flower, the red line, the first groove? Once you establish this you can simply pour your cereal, or pasta, or rice, etc, up to those markers. The more you do this at home the easier it will be to eyeball serving sizes when eating out or at a dinner party or a lunchtime meeting at work.

If you want some updated items for reference, here is my current list:

  • A cell phone without a case is about 2oz of fish – stack 2 phones and estimate 4oz beef, chicken, or pork.
  • A computer mouse is about ½ a cup – for fruits or vegetables or grains and pasta.
  • A yogurt cup is usually about 5oz in weight and ½  cup volume  - a good visual for pasta or rice.
  • A soda can is 12 fluid oz or 1 ½ cups -  this is a great place to start for vegetables – you can always have more vegetables.

Again, the best way to eyeball your serving sizes is to practice at home by measuring your portions when you have the time and resources. The more you do this, the better equipped you will be when eating outside the home.  Believe me, after being a registered dietitian for nearly 15 years, I consider eyeballing portions my hidden talent.


pinterest serving sizes
Jeannie Boyer


Jeannie Boyer is a registered dietitian, licensed in South Carolina with over 10 years of experience with weight loss and weight management along with a background in clinical nutrition. She obtained her B.S. in nutrition from East Tennessee State University followed by a dietetic internship at Emory Hospital in Atlanta, GA. Jeannie spent many years working with a bariatric practice in California before moving back to the south and is excited to continue working with weight management at East Cooper Bariatric Surgery.