Walk into any gym and you'll hear it. Someone is swearing by four shakes a day. Another person is terrified that "too much" will wreck their kidneys. It’s a mess of conflicting advice that usually leaves people staring at a chicken breast wondering if it's enough or way too much. Honestly, the answer to what percentage of my diet should be protein isn't a single magic number that applies to your neighbor, your boss, and your marathon-running cousin.
It depends.
The National Academies of Sciences, Engineering, and Medicine suggests that for adults, protein should make up 10% to 35% of total daily calories. That is a massive range. If you eat 2,000 calories, that’s anywhere from 50 grams to 175 grams. Why the gap? Because a sedentary office worker has vastly different cellular needs than a CrossFit athlete or someone trying to maintain muscle while losing thirty pounds.
The "Bare Minimum" vs. Optimal Performance
Most people look at the Recommended Dietary Allowance (RDA) and think that’s the goal. It isn't. The RDA for protein is currently set at 0.8 grams per kilogram of body weight. For a 165-pound person, that’s about 60 grams of protein.
Here is the kicker: the RDA is literally defined as the minimum amount you need to keep from getting sick or losing lean tissue. It is the floor, not the ceiling. If you are active, 0.8 grams is probably going to leave you feeling recovered like a wet noodle.
Research, including a prominent 2018 meta-analysis published in the British Journal of Sports Medicine, suggests that for those looking to build muscle, the "sweet spot" is closer to 1.6 grams per kilogram. If you're doing the math in your head, that's double the RDA. When we talk about what percentage of my diet should be protein, we have to factor in your activity level first. If you’re lifting heavy three times a week, hitting that 25% to 30% mark is often where the magic happens for recovery.
Why Your Age Changes the Math
As we get older, our bodies get "resistant" to protein. It’s a process called anabolic resistance.
Basically, a 20-year-old can eat a small yogurt and their muscles start the repair process. A 60-year-old might need double that amount of leucine—a specific amino acid—to trigger the same muscle protein synthesis. Dr. Gabrielle Lyon, a functional medicine physician who specializes in "muscle-centric medicine," often argues that middle-aged and older adults should prioritize protein even more than the young "gym bros" do. This helps stave off sarcopenia, which is just the fancy medical term for losing muscle as you age. Losing muscle is how you lose independence.
🔗 Read more: Ingestion of hydrogen peroxide: Why a common household hack is actually dangerous
Stop Thinking in Percentages, Start Thinking in Grams
The problem with focusing solely on what percentage of my diet should be protein is that percentages are shifty.
If you go on a "crash diet" and cut your calories to 1,200, but keep your protein at 20%, you’re only getting 60 grams. That’s not enough to protect your metabolic rate during a deficit. Your body will literally start burning your own muscle for fuel because it’s easier to break down than stubborn fat stores. This is why people get "skinny fat." They lose weight, but their body fat percentage stays high because they lost muscle too.
A better way? Aim for a goal weight gram count. Many experts, including sports nutritionists like Dr. Bill Campbell, suggest aiming for 0.7 to 1 gram of protein per pound of target body weight.
- If you want to weigh 150 lbs, aim for 120-150g of protein.
- If you are significantly overweight, use your "lean body mass" instead so you don't overconsume.
- On a 2,000-calorie diet, 150g of protein is 600 calories.
- That’s 30%.
See how that fits into the 10-35% range? It’s high, but it’s manageable.
The Thermal Effect: The Secret Weight Loss Weapon
Protein has a "secret" advantage over carbs and fats: it's hard to digest.
This is known as the Thermic Effect of Food (TEF). When you eat fat, your body uses about 0-3% of those calories just to process them. Carbs take about 5-10%. Protein? It takes about 20-30% of its own calories just to be broken down and used.
You’re essentially "burning" calories just by choosing the steak over the pasta. Plus, protein is the most satiating macronutrient. It suppresses ghrelin (the hunger hormone) and boosts peptide YY, which makes you feel full. If you’ve ever tried to overeat plain chicken breasts, you know it’s physically difficult. Overeating pizza? Easy.
💡 You might also like: Why the EMS 20/20 Podcast is the Best Training You’re Not Getting in School
Is High Protein Dangerous?
You've probably heard that high protein diets "destroy" your kidneys.
For people with pre-existing chronic kidney disease (CKD), yes, they need to be very careful and follow a low-protein protocol under a doctor's eye. But for healthy individuals? The data isn't there. A study led by Dr. Jose Antonio followed athletes consuming extremely high amounts of protein (over 3 grams per kilogram) for a year. The result? No changes in kidney function or lipid profiles.
Your kidneys are remarkably good at filtering out the nitrogen byproducts of protein. Just make sure you're drinking enough water. Protein metabolism requires hydration.
The Quality Debate: Plants vs. Animals
Does it matter where the protein comes from? Sorta.
Animal proteins (eggs, whey, beef, fish) are "complete," meaning they have all the essential amino acids in the right ratios. Plant proteins often lack one or two essential aminos. If you're vegan, you can't just count the "total grams" and call it a day without variety. You need to combine sources—like rice and beans or soy—to ensure you're getting the full profile.
Soy and quinoa are rare plant-based "complete" proteins, but you usually need to eat a higher volume of them to get the same amount of leucine found in a small piece of salmon.
How to Actually Hit Your Target
Hitting 30% protein is actually kind of annoying if you aren't prepared. Most people eat a carb-heavy breakfast (bagel), a moderate-protein lunch (sandwich), and then try to cram 80 grams of protein into dinner.
📖 Related: High Protein in a Blood Test: What Most People Get Wrong
That doesn't work well. Your body is better at processing protein in "pulses" of 30 to 50 grams throughout the day.
- Start the day with 30g. Eggs, Greek yogurt, or a scoop of high-quality whey. If you skip protein at breakfast, you're playing catch-up all day.
- The "Palm" Rule. A piece of meat or fish the size of your palm is roughly 20-25 grams.
- Snack smart. Swap chips for beef jerky, edamame, or cottage cheese.
- Liquid help. If you can't chew another piece of chicken, a shake is a perfectly valid tool. It's not "cheating."
Finding Your Specific Number
To figure out exactly what percentage of my diet should be protein, look at your current body composition and your goals.
- Weight Loss Focus: Aim for the higher end (25-35%). You need the satiety and the muscle protection.
- Endurance Athlete: You need more carbs for fuel, so you might sit comfortably at 15-20%, but your total calories will be higher, so the total grams still stay high.
- General Health/Maintenance: 15-25% is usually the "goldilocks" zone for most people who just want to feel good and stay healthy.
The biggest mistake is staying at the 10% bottom limit while trying to live an active lifestyle. You'll feel tired, you'll lose hair, and your recovery will tank.
Actionable Next Steps
Stop guessing. For the next three days, don't change how you eat, but track every bite in an app like Cronometer or MyFitnessPal. Look at your average protein percentage.
If you're under 15%, try to increase it by just 5% this week. Add one high-protein food to your breakfast. If you’re already at 20% and hitting a weight loss plateau, try bumping it to 30% while keeping total calories the same.
Notice how your hunger levels change. Most people find that once they hit that 25% to 30% mark, the "cravings" for junk food start to fade because the body is finally getting the nitrogen and amino acids it needs to maintain its structural integrity. It's less about "willpower" and more about giving your biology the right tools. Keep your water intake high, watch your energy levels, and adjust based on how your muscles feel the day after a workout.