Understanding how to calculate portion size

If you are new to logging or have been at it for a while, you may have wondered about the best way to measure or calculate portion size. A key aspect of tracking is accurately determining how much food and drink you’ve consumed.

If you don't measure your portions, you’ll often underestimate how much you are taking in. If you are trying to lose weight, this can lead to frustration and a lack of progress. Figuring out portions of commonly consumed foods, such as bread or crackers, where the serving size is listed on the package, is straightforward. However, what about figuring out portions of pasta, meat, peanut butter, and oils?

This article delves into the details of calculating the portion size of foods and drinks, with specifics around weighing, measuring, and estimating food portions for weight loss.

How to calculate portions with accuracy Weigh your food!

Weighing is the most accurate way to measure or calculate portion size. You can purchase a kitchen scale at most big box stores or online. We suggest investing in a digital scale as opposed to an old-fashioned spring-loaded scale. The digital scales are easier to use and more accurate. With a digital scale, you can easily zero out the weight of the container as well as select different units of measure (e.g. grams, ounces, etc.). Serious about losing weight? Check out MyNetDiary and start weighing your food!

Measuring volume- Use measuring cups & spoons

Another approach to calculating portion size is to use measuring cups and spoons or a glass measuring cup to determine volume (e.g., cups, fl oz, ml, etc.). These items can be purchased at big box stores or online.

Using a measuring cup designed for liquids is easier, more accurate, and less messy. See below for an example of this type of measuring cup.

When measuring the volume of a solid (e.g. flour, cereal, etc.), you can use standard measuring cups (if measuring weight is not an option). Level off the contents with the flat side of a knife to get an accurate measurement. Use metal or plastic measuring cups, whichever you prefer. Standard measuring cups look like those shown in the photo below.

You can use measuring spoons to measure very small amounts of liquids or solids. Level off solids with the flat side of a knife. Use metal or plastic measuring spoons—whichever you prefer. They look like the ones shown in the photo below.

Buy several sets of measuring cups and spoons. That way, you always have one clean and ready for measuring.

Estimating portion size

If you have already started recording your intake, then you know how difficult it is to estimate portion size. MyNetDiary created a Portion Guide to aid in the process. Look for the open book icon (see example below) when tracking to access the guide.

Tip: Metric system is available for weight, length, and volume measurements.

For more help estimating portion size when you cannot measure, check out the Serving Size Card from the National Heart, Lung, and Blood Institute. This card displays portion size using familiar objects. Also, visit WikiHow for more helpful visual representations of portion size. See below for a quick summary.

Grain Products	1 cup cereal flakes = 1 fist 1/2 cup cooked rice, pasta or potato = 1 tennis ball 1 oz slice of bread = 1 cassette tape 1 oz chips = 1 handful
Vegetables, and Fruit	1 cup salad greens = 1 baseball 1 medium baked potato = 1 computer mouse 1 medium piece fruit = 1 baseball 1/2 cup fresh fruit = 1 tennis ball 1/4 cup raisins = 1 egg
Dairy and Cheese	1½ oz cheese = 4 stacked dice 1/2 cup ice cream = 1 tennis ball
Meat and Protein Alternatives	3 oz meat, fish, or poultry = 1 deck of cards 3 oz fish fillet = 1 checkbook 2 tablespoons peanut butter = 1 ping pong ball
Fats	1 teaspoon = 1 dice or tip of a finger 1 tablespoon = 1 poker chip

Tip: We tend to serve ourselves more food when we use larger dishes and less food when we use smaller dishes. If you are trying to lose weight, consider using smaller plates and bowls if you are not able to measure your portion size.

Always measure calorie-dense foods

Some foods are so high in calories that an error in portion size means a large error in calorie intake. If you are focusing on selecting portions for weight loss, this can translate to unexpected calorie intake and potentially impact your weight loss.

Consider always measuring the following items:

• Fats and oils
• Nuts, nut butters, seeds, and seed butters
• Avocado, guacamole, pesto, dips, and salad dressings
• Chocolate
• Alcohol
• Syrups, honey, and sugar
• Dried fruit
• Trail mix

Always measure comfort & snack foods

Let’s be honest. If you consume foods straight out of the original packaging, you have no idea how much you have eaten unless you eat the entire package. Portion out what you want, log it, and then enjoy it. By implementing this simple rule, you can save hundreds of calories.

Here is a list of foods people tend to overeat unless portioning out ahead of time:

• Ice cream, gelato, or frozen yogurt
• Cookies
• Crackers
• Chips
• Cheese
• Peanut butter
• Nuts
• Guacamole

Make up your own list of items and post somewhere near the food - This will help remind you to measure out these items before eating them!

Tricky portion sizes

Food labels typically display serving size as consumed, but not always. There are many exceptions that make logging a bit tricky. Here are some tips that will help you calculate portion size.

• MyNetDiary uses the USDA National Nutrient Database as the foundation for the food item file. If you visit the USDA database, choose “Standard Reference” under “Select Source” - this will allow you to search basic or generic foods to find equivalent weights and measures, check to see if there is a cooked version available, and check how food items are worded if you can’t find them in MyNetDiary.
• If you eat a food that is cooked, then ideally, log the cooked generic version of the food item. Doing so will give you the most accurate calories and nutrient content.
• Pasta and rice. Food labels typically display 2 oz dry, which makes close to 1 cup cooked (about 220 calories). USDA has a number of cooked pasta and rice options, so I would choose one of those unless you use a flavored convenience product.
• Oatmeal and other cooked cereals. Food labels typically display the dry weight and/or volume that corresponds to 1 cup of cooked product (about 160 calories). USDA has cooked generic versions, so use those unless you use a flavored convenience product.
• Meats, fish, and poultry. Most meats shrink about 25% with cooking. For example, if you started with 4 oz raw ground beef, then the actual cooked weight of the patty is closer to 3 oz. Food labels, if available, typically list raw weight but USDA has many cooked versions of various meats to select from.
• Fresh fruit. For fruits with edible skin, there are food items with and without the skin, so choose the one that you consume. For bananas, peel the banana, then measure the weight to be consumed. If you can’t measure the weight, then measure the length and find the closest description (small, medium, etc.).
• Tip: add “raw” to your name search to find basic fresh fruit or vegetables.

Measurement equivalents

The measurements provided in the table below might be helpful when logging.

English	Metric
1 teaspoon = 0.33 tablespoon	5 ml
3 teaspoons = 1 tablespoon	15 ml
2 tablespoons = 1 fl oz = 1/8 cup = 0.125 cup	30 ml
4 tablespoons = 2 fl oz = 1/4 cup = 0.25 cup	60 ml
6 tablespoons = 3 fl oz = 0.38 cup	90 ml
8 tablespoons = 4 fl oz = 1/2 cup = 0.5 cup	120 ml
16 tablespoons = 8 fl oz = 1 cup	240 ml
16 fl oz = 2 cups = 1 pint = 0.5 quart	480 ml
32 fl oz = 4 cups = 2 pints = 1 quart	960 ml (just less than 1 Liter or 1000 ml)
1 oz	28 grams
3 oz	85 grams
3.5 oz	100 grams

Ask us for help

If you need help logging a food item or just have questions about nutrition, weight, or diabetes, post them at the “Ask RD” forum in the Community. We are available to help.

Still new to MyNetDiary? Learn more today by downloading the app for FREE.

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