For many people, ketosis is usually maintained best when protein stays around 0.6 to 0.9 grams per pound of lean body mass per day, or roughly 1.3 to 2.0 grams per kilogram of lean body mass. This is often a practical range that allows the body to maintain muscle, repair tissue, and support health without pushing protein intake so high that ketone production is more likely to decline.

In real life, many people still remain in ketosis with moderate to fairly high protein intake. A moderate protein intake is often around 70 to 120 grams per day. A higher intake that is still often workable may be around 120 to 160 grams per day. Once intake regularly rises above 160 grams per day, it becomes more likely for some people to notice reduced ketone levels, though this is not a hard cutoff and does not apply equally to everyone.

Body size changes everything. A smaller sedentary person may notice reduced ketones if they regularly go much above 100 to 130 grams per day. In contrast, a larger, more muscular, or more active person may remain in ketosis at 140 to 190 grams per day, and sometimes even more. This is why general keto advice can be misleading when it ignores differences in body composition and activity level.

A simple estimate by body type can help make this more practical. A small person with low activity may do well around 70 to 100 grams of protein per day. An average-sized person with moderate activity may often function well around 90 to 140 grams. A large or muscular active person may often tolerate 120 to 180 grams without major issues. These are not exact limits, but they are useful reference points.

It is also important to understand the difference between too little, enough, and too much protein. Too little protein can increase the risk of muscle loss, poor recovery, weakness, and reduced resilience. Enough protein supports health, preserves lean mass, and usually still allows ketosis when carbohydrates remain low. Too much protein becomes more likely when intake clearly exceeds the body’s repair and maintenance needs, especially if total calories are also high and carbohydrates are not tightly controlled.

For many average adults, the range where protein may begin to noticeably weaken ketosis is often somewhere around 130 to 170 grams per day or more. Even then, this is still only a rough estimate. Some people will remain in ketosis above that range, while others may see ketones fall sooner.

The main point is that protein needs to be appropriate, not minimal. Keto is not about avoiding protein at all costs. It is about keeping carbohydrates low enough to allow ketone production while eating enough protein to maintain strength and health. The exact amount that is too much depends on the individual, but for many people, the answer lies not in eliminating protein, but in staying within a range that matches body size, activity, and metabolic goals.