Paleo, keto, Atkins, or Dukan — high protein diets are trendy and appealing with their promise of weight loss without hunger. Plenty of people jump at the chance to enjoy practically unlimited bacon burgers (without the bun). Protein is one of the essential nutrients your body needs to build and repair tissue, too, so you can feel virtuous while you tuck in. But is there such a thing as eating too much protein? And if so, what are the consequences?
Kidney damage
Eating excessive protein can damage kidneys. While people with healthy kidneys may not be harmed by a high protein diet, especially in the short term, global studies find that long-term use of high protein diets can lead to kidney disease.
People who already have poor kidney function or are at risk of kidney disease, such as diabetics and obese people, are at greater danger from overeating protein. However, kidney stones and gout can also be a consequence of high protein diets.
Some research suggests that animal protein is at fault here. Higher levels of plant protein don’t show the same pattern.
Excess protein
Your body doesn’t really have a good way to store protein. Protein can be burned for fuel, in which case some of that protein will be converted into glucose, your brain’s energy source. However, your body will usually produce glucose from carbohydrates, so protein doesn’t lead to higher levels of blood sugar.
What isn’t burned for fuel will be stored as fat.
Bone loss
You might expect that more protein would lead to strong bones, but it actually is associated with bone loss. With overconsumption of protein, calcium is excreted in urine and less stays in the body.
A study comparing women who ate red meat five times a week with those who had it only once a week found that the high protein eaters had a significantly higher risk of forearm fractures.
How much is too much?
Harvard Medical School points out that there is little agreement on just how much protein people need, or how much is too much. There is no standard recommendation.
Popular suggestions include .8 grams per day for every kg of body weight, which works out to about 51 grams of protein for a 140-pound person; 46 grams for an average woman and 56 grams for an average man; or 10% of total calories.
You may find it easier to use the Plate Method than to count grams. Or, since much of the research showing negative consequences of too much protein involve animal protein, try the Mediterranean diet to increase the proportion of plant foods you eat.
If you have questions about how much protein you should eat each day, ask your doctor. Find a doctor.