Why eating beans feels inefficient for increasing protein intake

I spent 1.5 hours eating my lunch yesterday. I don’t think I’ve ever chewed food for that long, and it’s likely because I was trying to get the majority of my lunchtime protein through beans. Just as it sounds, as an omnivore, eating beans to meet one’s total daily protein goals (for me, that’s somewhere between 100-120 grams per day given I have a rigorous workout regimen and keep active) feels extremely, extremely inefficient. Why does it feel this way? It’s because beans are far less protein dense than meat and require eating much larger volumes of food to get the same amount of protein. And for someone who is generally just not used to eating a large quantity or volume of food per meal (and was previously used to skipping breakfast completely pretty much every day, even on days I work out), this is a bit of a rude awakening and hard adjustment. According to ChatGPT, this inefficiency comes down to biology and nutrition:

  • Lower Protein Density: Animal proteins (like chicken or beef) deliver about 20-25g of protein in a 100-calorie serving. Beans provide about 6-9g of protein per half-cup (100 calorie) serving. To match a standard 6-oz. chicken breast (50g of protein), you would need to eat nearly three cups of cooked beans; that is bonkers to me.
  • Carbohydrate Overhead: Beans are roughly 70% carbohydrates. Because of this, trying to hit high daily protein targets (e.g. 120 grams!!) solely through beans will likely cause you to exceed your daily caloric or carbohydrate limits.
  • The Fiber Fullness Factor: Beans are loaded with dietary fiber. While great for health, the sheer volume of fiber creates extreme early satiety, making it physically uncomfortable to consume enough beans to reach heavy protein goals.
  • Amino Acid Spikes: Most beans are considered “incomplete” proteins because they are lower in the essential amino acids methionine and cysteine. While your body naturally balances amino acids over the course of the day, some fitness goals require a concentrated spike of all nine essential amino acids at once for optimal muscle synthesis.

So the way to get around this if you want to eat mostly plant-based is to try inserting as many of the small number of complete plant proteins into your diet as possible, which is mostly: SOY, SOY, and SOY. So that means — tofu and all tofu products, like soy milk or tempeh. It could mean incorporating small numbers of oddly complete protein plant foods like quinoa, chia seeds, or hemp seeds, though all are highly caloric, so you have to limit to a tablespoon or less per serving). The good thing is that I am an omnivore, so I will still be eating meat and seafood. But I don’t usually eat those things at breakfast, so animal protein, at most, would be for consideration only for lunch and dinner. Nuts are all great but are incomplete proteins, and like the seeds noted above, are highly caloric and thus should be eaten in smaller quantities (toppers as opposed to the main show – who is going to eat an entire cup or two of nuts in a single sitting?!).

I’m in a period of diet adjustment, and it feels bumpy and funny, and I feel like I am just always chewing food, but I will see what tweaks I can continue to make. As my friend says, this is always a work in progress.

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