Visualizing Portion Sizes

This is a guest blog post by Larry Istrail

Estimating portion sizes is arguably the most important, yet difficult aspect of approximating your daily caloric intake. Simply stated, the inability to assess serving sizes yields inaccurate caloric estimations and potentially less weight loss, or more weight gain.

For these reasons, at PhotoCalorie we believe learning to estimate portion sizes correctly is the first step to achieving your goals. The best way to do this is by using your hands. Since weighing every food you eat is not a reasonable solution, hands offer a practical method that anyone can implement, whether at home or at your local Denny’s.

(c) PhotoCalorie 2010

The photos above are examples of how a hand can be an excellent measure for a variety of different foods. (More serving size photos, such as the ones above, can be found on our website:

For example, once you can memorize that 3 ounces of meat is about the thickness of a deck of playing cards and the size of your palm, all meats are at your mercy. Steaks, chicken breasts, and salmon filets will be no match for your new portion assessment tools.

Unfortunately food industries and restaurants make this practice more difficult than it should be, serving your drinks and foods in giant packages, cups and bowls.

In dietary research, it turns out people have terrible trouble estimating their serving sizes. Dr. Brian Wansink, a professor of nutritional science and human behavior at Cornell University, has demonstrated that as portion sizes increase, so too does your measurement error, and even developed a mathematical formula to predict it. Practically, this means that you are less likely to correctly estimate your portion size if you eat foods from the plates or cups they were served in.

Buying smaller plates and glasses and serving bowls can be very effective at combatting this. Despite sounding like a silly celebrity secret to weight loss, scientists studying food behavior consistently find that the size of the plate effects how much you eat. Basically, the bigger the plate, the more you eat. Doesn’t matter the type of food or type of person. Not even nutrition experts seem to be immune to unconsciously serving themselves more food if they have a bigger plate.

The same is true for serving bowls and liquids. People eating M&Ms or popcorn from larger containers eat more without even realizing it. In Dr. Wansink’s popcorn experiment, those given the large bucket of popcorn ate 53% more popcorn than the those given the medium bucket, even though the popcorn was stale!

Glasses and cups are no different. Even bartenders pour more liquid into a wider shot glass when asked to pour a shot. People asked to pour a cup of juice into a skinny or wide glass pour less into the skinny glass. You can read more about this research here.

What to do:

Hands offer a practical tool for estimating your daily food intake. To minimize the effects of growing portion sizes and food industry influence, buy smaller plates and glasses, and serve food in smaller serving bowls.

Larry Istrail is the Co-Founder and nutrition lead of PhotoCalorie, LLC, a start-up company that has created a web based food journal and nutrition search engine, offering the ability to take pictures of your food, search nutrition facts for multiple foods in one step, and share your journal with others. He also maintains the PhotoCalorie Blog, dispensing practical information obtained from dietary research and food-related current events.
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  • Mari

    Great post. And Mindless Eating, by Dr. Brian Wansink is truly a fascinating book. It’s study after tireless study of how rarely you actually accurately estimate how much you eat, will eat and how much of a role outside factors play on us with focus groups. He totally turns us all into lab rats and shows us the deal. It’s fabulous and one of the best (diet) books you can read that will help rewire your thinking to be just a little bit more aware of what you’re putting in your mouth.

  • GrowingRaw

    I agree that people have trouble measuring portions but don’t realise it. Well, they don’t measure, because they already have an idea in mind of what a serving size is. That idea is often inaccurate. It can work the other way too though. For example, national nutrition surveys in Australia have shown that although many people think they’re eating the recommended 5 servings of veg a day, they’re often not actually reaching that target. Sometimes they think that eating 5 different types of vegetables is enough, but they haven’t eaten a large enough portion of each vegetable.