The Diet Question You Should Be Asking But Aren’t

getting-enough-fiber I could buy a lot of legumes if I had a dollar for every time someone asked me where I get my protein from (I eat a plant-based diet). It is a question I grow tired of, not only because of how frequently it is asked, but because of the lack of basic knowledge behind it.

There are a number of industries that have sold the idea of a high-protein diet to the American public. The meat and dairy industries benefit, of course, but so does the fitness market, especially the companies that sell protein powders derived from a wide array of sources, some animal-based, some plant-based. Protein is a big money maker these days, but should it be?

There is no question that protein is essential for healthy human function. It not only builds the body’s tissues, but it generates and regulates hormones essential to the efficient running of all the body’s various systems. There are eight amino acids the human body can’t synthesize from fat or carbohydrate, and so those essential amino acids must be consumed in the diet. So we definitely can’t ignore protein. But neither should we elevate it to the level it has been.

According to the American Council on Exercise, getting around 15 percent of calories from protein is sufficient, not only for the maintenance of hormone function, but also for maintaining or building muscle. Additionally, the maximum amount of protein the body can use for muscle-building is 2 grams/kg of bodyweight. (See “Optimal Protein” references below.)

The focus, then should not be on how many grams of protein you are consuming each day or with each meal, but should start with how many calories you need to maintain a healthy weight and fuel your desired activity level. A male adult athlete will need a relatively large amount of calories, and therefore a relatively high number of grams of protein to sustain his activity level; whereas a sedentary, overweight male adult should be consuming relatively few calories (to lose weight) and therefore relatively little protein.

Not only is excess protein not beneficial to the body, but it may be harmful. A number of studies have shown that diets high in animal protein are closely associated with increased risk for heart disease, diabetes, stroke and certain cancers. (See links to resources at the end of this post.) Consuming too much protein in one sitting also taxes the kidneys, and long-term, repeated overconsumption may lead to kidney stones, ketosis and even kidney failure.

In the meantime, no one is ever asking me where I get my fiber from. Nor are they worrying about how many grams of fiber they are consuming in their own daily diet. This seems odd to me, since fiber is essentially a dietary superhero: a diet high in fiber is associated with lower risk for heart disease, high cholesterol, type 2 diabetes, stroke and diverticulitis. Yet, Americans consume less than half of the recommended 35 grams of fiber daily, according to a 10-year study published in 2012.

Not only is fiber great for your health, it appears to beat protein when it comes to weight loss as well. According to researchers conducting the Seventh Day Adventist Studies, Women who eat a vegetarian diet weigh, on average, 19 pounds less than non-vegetarian women in the same population, and vegan women weigh 34 pounds less. For men, the story is much the same, with vegetarians weighing 16 pounds less and vegans weighing 32 pounds less than their non-vegetarian counterparts. These studies compare individuals from the same population who have similar demographics and lifestyle habits (due to their religious practices) making this truly an apples-to-apples study.

Here is one final thing to consider. Protein is present in all whole plant food in some quantity. There tends to be very little in fruits, a bit more in starchy vegetables, and quit a lot in leafy greens, grains and legumes. But there is no fiber at all in meat, eggs, poultry, dairy or fish. Zero grams. Zero point zero, actually.

So the next time someone asks me where I get my protein, I will say, “Everything I eat has protein in it. But where are you getting your fiber from?”


Optimal Protein Intake:

  • More is not always better. Total daily protein intake should not be excessive and should be reasonably proportional (≈15% of total caloric intake) to carbohydrate (≈55% of total caloric intake) and fat (≈30% of total caloric intake). Protein consumption beyond recommended amounts is unlikely to result in further muscle gains because the body has a limited capacity to use amino acids to build muscle. – Natalie Digate-Muth, MD, MPH, RD, ACE Senior Consultant for Healthcare Solutions, 2011 ACE Fit For Life.
  • 2g/kg is the maximum usable amount of protein. –  Tipton, K.D. 2011. Symposium 2: Exercise and protein nutrition: Efficacy and consequences of very-high-protein diets for athletes and exercisers. Proceedings of the Nutrition Society, 70(2), 205–14.

Protein, Ph and Kidney Function
High-Protein Diet and Cancer Risk
Animal-Based Protein, Heart Disease and Mortality
Benefits of Fiber

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