On losing weight (Part 4 – Volumetrics)

Calories and grams: the building blocks of a slimmer you.

What is volumetrics?

My previous post in this series was about a cell phone app called Noom. Noom builds its program (and its food database) on a concept called volumetrics.

CNN article on volumetrics

Put simply, volumetrics is all about eating food that has a low calorie density so that you will feel satisfied, but will not gain weight. The measure used by Noom is calories per gram, and it’s very easy to calculate. Take a look at the following label:


You only need to look at two items in the list to figure out the calorie density of this food: 200 calories per serving, and 172 grams per serving. So, for this food you would divide 200 by 172 and you come up with 1.16 calories per gram. That’s actually quite a good calorie density.

Why do I care?

There’s two numbers here:

  • Grams – The total amount of food you eat. In theory, the higher this number, the more satisfied (or full) you will feel after eating a meal.
  • Calories – The amount of the food that is absorbed by your body. In theory, the higher this number, the more weight you will gain after eating a meal.

It makes sense that you want the grams to be high, so that you feel satisfied, and you want the calories to be low so that you don’t gain weight. It’s that simple.

Now, given that 3600 calories is roughly a pound, and also given that 454 grams is a pound, we can calculate that a density of about 7.9 calories per gram indicates that every single bit of a given food (after you have exceeded your basal metabolic rate) will go directly to your gut. Wegmans brand butter, for example, has 100 calories in a 14g serving, yielding a density of 7.1 calories per gram. That’s pretty close to the worst possible number.

NOTE: This is a major simplification of the topic. There are many other issues that can come into play that will affect how calories relate to weight gain / loss. These factors are taken into account in something called the thermic effect of food. For a very interesting application, see this article on number of calories in a banana. This is a relatively new topic of research, and the contributing factors and implications are not fully understood at this time.

Noom’s color coding system

Noom uses a red / yellow / green system to indicate how likely it is that a particular food will cause you to gain weight. This is largely based on the calorie per gram figure, although other factors are considered as well.

Typically, foods with less than 1.0 calories per gram are considered to be green. Between 1.0 and 3.0 is yellow, and above 3.0 is considered to be red. Considerations such as how long a food takes to digest (keeps you feeling full longer) and how much fat content the food has can also come into play, but the calorie density is the main indicator.

Noom recommends that you try to structure your diet in such a way that about 50% of the calories you consume are in the green category, about 35% are yellow, and about 15% are red. Based on my goal of 1800 calories per day, that means that 900 of those should be from green foods, 600 from yellow, and 300 from red.

Some food examples

Let’s take a look at several examples of calorie density calculations:

Green foods

 CaloriesGramsDensity (cal / g)
Egg whites30570.5
Quaker instant oatmeal160433.7
Whole wheat mini pitas110482.3
Red grapes901280.7
Italian blend salad15900.2
Fat free milk902400.4

Yellow foods

 CaloriesGramsDensity (cal / g)
Whole egg70501.4
95% lean ground beef150851.8
Pork chop160851.9
Haddock 1001130.9
Extra virgin olive oil120148.6
Apple juice1102400.5

Red foods

 CaloriesGramsDensity (cal / g)
Turkey bacon45281.6
Pop tart210504.2
80% lean ground beef210852.5
Potato chips160285.7
Whole milk1502400.6

The color categorizations above are all according to the Noom food database. I’m not sure I completely agree with all of the assigned colors. For example, I would personally consider haddock to be a green food. Noom doesn’t, though.

Some of the anomalies have a very good reason for being categorized the way they are, though. Take whole milk, for example. While its calorie density is well under 1.0, close to half the 150 calories (70 of them) are delivered in the form of fat. Given that this is in a quickly digested liquid form, it makes sense for it to be a red item. Try to “fill up” on milk sometime. Good luck with that.

That’s a lot of food

If you follow Noom’s suggestions and eat 50% of your calories from “green” (very low calorie density) foods, then it will take a lot of food to meet your daily calorie goals. For example, if you were to eat only baby carrots all day, and your daily caloric intake goal is 1800 calories, then you would need to eat almost 5 pounds of baby carrots to get 900 calories (50% of your goal).

This is a silly example, but it illustrates the concept that you need to eat large portions of green foods to provide sufficient nourishment for your body. It can take a very long time to eat such large quantities of food. You wouldn’t be able to easily do it within 3 normal meal times. You would need to be almost continually eating throughout the day.

So plan ahead! What foods will you eat? How much will you eat? How long do you think it will take to eat it all? In the next post, I will discuss the specific changes I have made to my diet.

– danBhentschel

3 thoughts on “On losing weight (Part 4 – Volumetrics)”

  1. Why is it called “volumetrics” if the calculation is based on mass rather than volume? It seems like volume would more directly correlate to fullness anyway, although it would have to be post-mastication volume…

    1. The same thought has occurred to me. I can’t really comment authoritatively since I didn’t come up with either the concept, or the name, but here is the conclusion I have come to after a decent amount of consideration. I believe that the original concepts of the practice were actually based on volume, rather than mass. However, the volume of a food is difficult to come by. It’s not something that is typically printed on a food label. I think that for most foods, the mass and (especially post-mastication) volume are relatively proportional to each other, such that the mass, which is a commonly available measure on most food labels, is a reasonable substitute for volume when calculating the relative calorie density of various foods. Hence, the term “volumetrics” probably is based on the underlying concepts, which are volume-based, but the practice uses mass because it is readily available to the consumer, and is a reasonable approximation of relative volume.

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