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The Scoop on How Your Body Processes Plant vs. Animal Calories

By Courtney Campbell

Not all calories are created equal. The 100 calories in a bag of potato chips and 100 calories of (purple) carrots are not the same nutritionally. You’ll feel much fuller eating a whole bag of carrots, if you can make it through.

The same goes for how plant and animal calories are processed by the body, which can impact the nutrients you receive and how you feel. We breakdown the difference in digestion time and protein usage in plant vs. animal calories to help you make an informed decision.

Digestion Time

Although we can scarf down a delicious meal in a matter of minutes, food can last in our 25-foot-long gastrointestinal tract between 36 hours and 72 hours. How long food stays in transit varies from person to person and by what you eat that day.

Why is digestion time so important? The longer food stays in your digestive tract, the more sluggish and constipated you can feel. But you can increase food transit time by changing up the amount of meat and fiber you consume.

Animal calories, which will always have higher amounts of fat than fruits, vegetables, and grains, take longer to digest, as fat molecules are more complex than carbs.

Additionally, vegetarian diets, which are generally high in fiber, tend to have a quicker transfer time (ranging from 27 hours and 54 hours) because fiber helps move food along, according to a study published in the “British Journal of Nutrition.” Those who consume less than 30 grams of fiber a day have slower transit times. So, up your fiber intake for quick digestion.

Protein Usage


The most common question posed to vegans and vegetarians is perhaps, “Where do you get your protein from?” It’s a huge misconception that a plant-based diet lacks in protein. With a variety of protein-packed grains and legumes at your disposal, it’s easy to reach the daily protein requirements on a plant-based diet.

Now that you’ve made sure you’re getting your fill of protein, what happens next? After it’s been ingested, protein breaks down into amino acids. There are 20 total animo acids, but your body only needs to ingest the nine amino acids it can’t produce. (These nine are called the essential amino acids.) Depending on whether the protein is plant- or animal-based, the rates at which the amino acids are absorbed and used within the body will vary.

Animal-based proteins contain all of the essential amino acids, and are considered complete. While there are some complete plant-based proteins, such as quinoa, chia, soy, and buckwheat, most plant-based proteins are incomplete. This means they’ll have to link up with a food or supplement that contains a protein-forming amino acid in your digestive tract to become complete. Nearly all whole foods, including leafy greens and veggies, satisfy this requirement. However, you may want to take a B12 supplement to ensure you’re ingesting all the essential amino acids.


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Although both plant and animal calories provide enough nutrients and protein, the choice between the two impacts how you feel. In addition to keeping your digestive tract moving, diets high in plant protein have also been linked to a lower risk of heart disease, reduced risk of Type 2 Diabetes, and limits weight gain.


purple carrot plant-based diet