If protein is good for muscle retention, fat loss, and satiety, wouldn't more always be better? Not exactly. There's a range where additional protein provides diminishing returns, and at extreme intakes, there are potential downsides worth knowing about.

The good news is that "too much protein" is considerably higher than most people eat — and for most people increasing protein is a bigger concern than overdoing it. But the ceiling is real, and understanding where it sits helps you set your targets sensibly.

What High-Protein Actually Means

Context matters here. The RDA for protein in the US is 0.8 g per kg of bodyweight — a figure designed to prevent deficiency in sedentary adults, not to optimize body composition or athletic performance.

By that standard, 1.2 g/kg would be "high protein." By the standards of someone training seriously, 1.2 g/kg is moderate.

Most research on protein for body composition and athletic performance converges on a practical range of 1.6–2.2 g/kg for active individuals. This is the range where benefits are well-established: muscle protein synthesis is maximized, muscle is preserved during a calorie deficit, recovery is supported, and satiety is high.

Above 2.2 g/kg, the evidence for additional benefit gets thinner. Above 3.0 g/kg, you're in territory where most studies show no further gain in muscle or performance — you're just eating more protein than you can use.

Where "Too Much" Begins

From a body composition standpoint, excess protein beyond what your body can use for muscle protein synthesis is either oxidized for energy or, at very high intakes, converted to glucose or fatty acids. It doesn't build more muscle indefinitely.

The practical ceiling for muscle building appears to be around 2.2 g/kg of bodyweight for most people. Some research in athletes and during aggressive recomposition supports going up to 3.0–3.1 g/kg, but the marginal benefit above 2.2 g/kg is small for most people.

For a 75 kg person:

• 1.6 g/kg = 120 g protein/day (lower end of the active range)
• 2.2 g/kg = 165 g/day (upper end of well-supported range)
• 3.0 g/kg = 225 g/day (higher end of research range)

Beyond 225 g/day for a 75 kg person, you're eating more protein than research shows to be useful for muscle or performance.

The Kidney Concern — Real or Overstated?

The most common worry about high protein diets is kidney damage. This concern comes from the fact that kidneys process protein waste products (primarily urea), and high protein diets do increase the workload on the kidneys.

The evidence suggests: high protein diets are safe for people with healthy kidneys. Multiple systematic reviews and meta-analyses have found no adverse effects on kidney function in healthy adults consuming up to 2.2–3.5 g/kg per day over months to years of study follow-up.

However, the picture changes for people with existing kidney disease. If you have chronic kidney disease, reduced kidney function, or are at elevated risk, dietary protein restriction is often recommended to reduce the kidneys' filtration load. High protein diets are contraindicated in this population.

If you have any history of kidney issues, check with your doctor before significantly increasing protein intake.

What Happens to Excess Protein?

Protein can't be stored in the body the way fat can. When you eat more protein than you need:

1. A portion is used for muscle protein synthesis and other protein turnover processes. 2. The remainder is deaminated — the nitrogen is stripped off and excreted as urea, and the carbon skeleton is used for energy. 3. At very high intakes, some protein-derived carbon skeletons may be converted to glucose (gluconeogenesis) or potentially to fat, though this pathway is less efficient and less relevant at typical dietary protein levels.

The practical implication: protein calories count, even if protein is harder to store as fat than carbohydrates. Eating 400 g of protein per day in an attempt to build muscle faster won't work — you'll just be running your kidneys harder and spending calories on protein that could come from cheaper carbohydrates or fats.

Setting Your Protein Target

Use the macro calculator to work out protein targets based on your weight, goal, and activity level. The tool applies the per-kg targets from research to give you a daily gram figure.

As a starting framework:

Most people who actively train sit comfortably at 1.8–2.0 g/kg. This covers almost all the benefit without eating impractically large amounts of protein.

Is High Protein Intake Sustainable?

One practical limitation of very high protein intakes is adherence. Getting to 250+ g of protein per day requires a lot of dietary focus — protein sources need to dominate almost every meal. Many people find it monotonous and difficult to sustain.

Higher protein intakes also increase satiety significantly. This is a benefit during fat loss, but at very high levels it can make it hard to consume enough total calories for muscle gain. If you're trying to bulk and eating 3 g/kg of protein, you may struggle to eat the carbohydrates needed to fuel training and achieve a calorie surplus.

A common practical balance for muscle-focused athletes: hit 2.0 g/kg of protein and fill remaining calories with carbohydrates and fat in proportions that support training and enjoyment. Chasing protein targets above 2.2 g/kg rarely improves outcomes meaningfully.

Signs You're Getting Enough (and Too Much)

Getting enough protein:

• Muscle soreness recovers within 48–72 hours of hard training
• Strength holds steady or increases during a fat loss phase
• Hunger is manageable between meals

Potentially eating more protein than needed:

• Very high urine output and strong-smelling urine (from urea excretion)
• Digestive discomfort — high protein diets can cause gas and bloating, particularly from protein supplements
• Significant dietary monotony or difficulty hitting calorie targets despite eating frequently

For most people eating in the 1.6–2.2 g/kg range with adequate calories and training, neither of these extremes is relevant. The sweet spot is wide enough that you don't need to be precise to the gram — getting into the range consistently matters more than hitting an exact number every day.