For most healthy adults, consuming more than 2 grams of protein per kilogram of body weight per day crosses into excessive territory. That’s about 150 grams daily for a 165-pound person. Below that threshold, your body handles protein well. Above it, you start taxing your kidneys, losing hydration faster, and potentially crowding out other nutrients your body needs.
The Recommended Range
The baseline recommendation for protein is 0.8 grams per kilogram of body weight, or about 0.36 grams per pound. For a 165-pound adult, that works out to roughly 60 grams per day. This number represents the minimum to prevent deficiency, not necessarily the optimal amount for someone who exercises regularly, wants to build muscle, or is trying to lose weight.
Health guidelines place the acceptable range at 10% to 35% of total daily calories from protein. On a 2,000-calorie diet, that upper end translates to about 175 grams. Most people land somewhere in the middle of this range without trying. The trouble starts when protein intake consistently exceeds 2 grams per kilogram of body weight each day, which is the threshold the Mayo Clinic identifies as excessive. For context, that level is most commonly seen in people following aggressive bodybuilding diets, eating multiple protein shakes daily on top of regular meals, or doing prolonged carnivore or keto-style diets heavy in meat.
What Happens When You Eat Too Much
Your body has no real way to store excess amino acids the way it stores fat or glycogen. When you eat more protein than your tissues can use for repair, muscle building, and other functions, the surplus gets broken down. Your liver converts the nitrogen from amino acids into urea, which your kidneys then filter out. This process demands extra water, which is why one of the earliest signs of protein overconsumption is persistent thirst or darker urine, even when you’re drinking what feels like enough fluid.
Other common signs include digestive discomfort (bloating, gas, constipation), particularly if your high-protein diet is displacing fiber-rich foods like vegetables, fruits, and whole grains. Bad breath is another telltale sign. When your body breaks down large amounts of protein, it produces ammonia as a byproduct, and that ammonia can make your breath noticeably unpleasant. This is especially common when protein intake is high and carbohydrate intake is low.
Kidney Strain and Who’s Most at Risk
For healthy kidneys, moderate protein surpluses are generally manageable. The real concern is for people with existing kidney disease or those at higher risk for it, including people with diabetes or high blood pressure. High protein intake forces the kidneys to work harder to clear waste products, and for kidneys already under strain, that extra load can accelerate damage.
The National Kidney Foundation recommends that people with chronic kidney disease who are not on dialysis follow a lower-protein diet, with an emphasis on plant-based protein sources. The exact amount varies by body size, nutritional status, and the stage of kidney disease. If you have any degree of kidney impairment, your protein targets will look very different from what fitness influencers recommend.
The Bone Health Question
One long-standing concern about high protein diets is that they leach calcium from bones. The logic seems straightforward: metabolizing protein creates an acid load, and your body pulls calcium from bones to neutralize it, leading to increased calcium in your urine. This concern has persisted for decades, but the research tells a more nuanced story.
High protein intake does increase urinary calcium excretion. However, it also boosts calcium absorption in the gut, raises levels of a growth factor called IGF-1 that supports bone formation, and lowers parathyroid hormone (which, when elevated, breaks down bone). According to USDA-published research, these beneficial effects offset the calcium losses. Multiple long-term population studies actually show that higher protein intake is associated with greater bone mineral density and fewer fractures. So for most people, high protein diets are not a bone health threat, as long as calcium intake is adequate.
Your Body Can Only Use So Much Per Meal
There’s a practical ceiling to how much protein your muscles can use from a single meal. Research consistently shows that muscle protein synthesis, the process of repairing and building muscle tissue, ramps up as protein intake increases but plateaus once you hit a certain dose. For most adults, that threshold sits around 30 grams of protein per meal. One study found that a 30-gram serving of beef maximally stimulated muscle protein synthesis, and eating more in that same sitting didn’t increase the muscle-building response.
That doesn’t mean protein beyond 30 grams per meal is wasted entirely. Your body still digests and absorbs it. The amino acids get used for other processes or oxidized for energy. And interestingly, the thermic effect of protein (the calories your body burns just digesting it) does continue to climb above 30 grams. In one controlled trial, a 50-gram whey protein dose produced a significantly higher thermic effect than a 30-gram dose, with the body burning about 18% of the meal’s energy during digestion compared to 13%. So the extra protein still costs your body energy to process, which matters if you’re trying to manage weight. But in terms of building muscle, spreading your intake across three or four meals tends to be more effective than loading it all into one or two.
Animal vs. Plant Protein at High Intakes
Where your protein comes from matters, especially at higher intake levels. A large study tracking over 400,000 participants for 16 years found that greater consumption of plant protein compared to animal protein was associated with lower overall mortality and lower cardiovascular disease mortality. The effect was meaningful: participants who replaced just 3% of their calories from animal protein with plant protein were 10% less likely to die from any cause during the follow-up period.
This doesn’t mean animal protein is inherently dangerous. But it does suggest that if you’re eating a high-protein diet, tilting the ratio toward beans, lentils, nuts, seeds, tofu, and whole grains offers a protective advantage. Animal protein sources often come packaged with saturated fat, while plant sources tend to bring fiber, antioxidants, and other compounds that support cardiovascular health. The type of protein you eat may ultimately matter as much as the quantity.
Practical Protein Targets
For most adults who exercise a few times a week and want to maintain or build muscle, somewhere between 1.2 and 1.6 grams per kilogram of body weight is a well-supported range. That’s roughly 80 to 110 grams daily for a 150-pound person. Older adults who are trying to prevent age-related muscle loss may benefit from the higher end of that range, since the body becomes less efficient at using protein with age.
If you consistently find yourself above 2 grams per kilogram (about 1 gram per pound of body weight), you’re entering the zone where returns diminish and risks start to accumulate. The extra protein won’t build more muscle, and your kidneys, hydration status, and digestion may pay the price. A simple check: if you’re experiencing persistent thirst, constipation, bad breath, or unusually dark urine despite good fluid intake, your protein load is worth reconsidering. Aim to spread your intake across meals in portions of 30 to 45 grams, favor plant sources when possible, and keep your overall diet varied enough that protein isn’t crowding out fiber, healthy fats, and the micronutrients your body runs on.