Protein Supplementation and Requirements

Protein is a building block for new muscle tissue and helps repair damaged muscle; a lesser role is to supply energy during intense exercise. People who exercise — especially those just starting to train — need 50 to 100 percent more protein than their sedentary counterparts (Coleman & Nelson Steen 1996). However, most Americans typically eat more protein than they need. The average daily intake for sedentary adults is approximately 100 grams per day, or 1.4 g of protein per kilogram of body weight (1 kg = 2.2 lb).

Requirements:

• Sedentary (no regular exercise): 0.8 g per kg. Example: a sedentary female weighing 125 lb (≈57 kg) needs 46 g of protein per day (57 × 0.8). Seventy percent should come from high-quality sources (lean meats, fish, eggs, low-fat dairy) — satisfiable with one cup of milk, one cup of yogurt, and 2–3 oz of lean meat; grains, starches, nuts, seeds, and legumes (including soy) provide the rest.
• Active (runs/cycles/swims/works out ≥3×/week): 1.2 to 1.4 g per kg (Lemon 1995). A 125-lb active female needs roughly 70–80 g/day — about 23–35 g more than her sedentary counterpart.
• Building muscle / actively weight training: 1.4 to 1.8 g per kg per day (Lemon 1995). Building 1 lb of muscle requires an additional 100 g of protein, met by adding 15 g per day for one week (an extra 2 oz of lean meat per day).

Bigger, not better: Any extra protein not used is ultimately stored as fat. Protein is broken into amino acids; if unused, these are broken down further and used as energy or stored as fat. Many weight lifters overdo supplementation and get stronger only because they've gained weight — bigger but no leaner. Excess protein by-products can contribute to dehydration and, long-term, can compromise kidney function. High-protein diets are usually high in fat, leaving little room for carbohydrates; inadequate carbohydrate intake means poor muscle glycogen storage and premature muscle fatigue.

Recommendations: Amino acid / protein supplements provide extra protein at great financial expense (some clients spend up to $200/month), are not proven safe or effective, and are not currently regulated by the U.S. FDA. Nonfat dry milk is an inexpensive, high-quality alternative (¼ cup = 11 g); soy-based protein powders help strict vegetarians.

The 1.4-1.8 g/kg/day muscle-building ceiling is now considered too conservative -- current consensus supports up to roughly 2.2 g/kg/day for people actively training for strength/hypertrophy, and higher still during a caloric deficit to preserve lean mass. The kidney-function caution has not held up in subsequent research for people with healthy kidneys; it remains a legitimate concern only for those with pre-existing renal impairment. And "not proven safe or effective" is dated for basic whey/casein protein powders specifically -- they're now well-supported as an effective, convenient way to hit a protein target, particularly around training. The core "extra protein doesn't build extra muscle by itself, and whole foods can meet these targets" framing still holds. See verification_note in this module's frontmatter.

• Protein builds and repairs muscle; minor role supplying energy in intense exercise.
• Exercisers (especially beginners) need 50–100% more protein than sedentary people.
• Sedentary intake averages ~100 g/day ≈ 1.4 g/kg; 1 kg = 2.2 lb.
• Requirement (sedentary): 0.8 g/kg — e.g. 125-lb (57-kg) female = 46 g/day; 70% from high-quality sources.
• Requirement (active ≥3×/week): 1.2–1.4 g/kg — 125-lb active female ≈ 70–80 g/day.
• Requirement (muscle building / weight training): 1.4–1.8 g/kg/day (source's original ceiling — see 2026 update).
• Building 1 lb of muscle = +100 g protein (≈ +15 g/day for a week ≈ +2 oz lean meat/day).
• Unused protein is stored as fat; excess can dehydrate and stress kidneys (source's original framing — see 2026 update on the kidney claim).
• 2026 update: current consensus supports up to ~2.2 g/kg/day (higher still in a deficit) for people training for strength/hypertrophy; the kidney-damage concern hasn't held up for healthy kidneys specifically; basic whey/casein protein powders are now well-supported as effective, not "unproven."
• Supplements are costly, unproven, FDA-unregulated; nonfat dry milk (¼ cup = 11 g) is a cheaper alternative.

• macronutrient-distribution — protein's share of total calories.
• high-protein-diets — protein and weight loss.
• sports-nutrition-overview — one of the four focus topics.
• sports-bars — companion sports-nutrition topic; bar protein content.