Does Ketosis Cause Kidney Damage?

The ‘Lean for Life’ program is mildly ketotic, and only for a brief portion of the program. It has not been associated with kidney damage or disease in individuals who have normally functioning kidneys.

Concerns regarding undue stress on the kidneys are often aimed at very low carbohydrate, very high protein ketogenic diets. Few studies have shown any actual damage, however. (Note: Although the Weight Loss portion of the ‘Lean for Life’ program is mildly ketogenic, it is not considered to be exceptionally “high protein” for most individuals.)

Dietary ketosis is among the most maligned and misunderstood concepts in nutrition medicine. Particularly among researchers who don’t actually treat patients, ketosis (the presence of ketone bodies in the urine) is often confused with ketoacidosis, which is a life-threatening build-up of ketone bodies due to muscle wasting and dehydration as in states of shock or uncontrolled Type 1 diabetes. In the Type 1 diabetic, the absence of insulin leads to a toxic build-up of blood glucose and an extreme break-down of fat and muscle tissue. This condition doesn’t occur in individuals who have even a small amount of insulin, whether from natural production or artificially administered. Whereas patients in ketoacidosis are closely monitored in Intensive Care Units, individuals in ketosis are amongst the healthy, active population.

Dietary ketosis is a natural adjustment to the body’s reduced intake of carbohydrates as the body shifts its primary source of energy from carbohydrates to stored fat. The presence of insulin keeps ketone production in check so that a mild, beneficial ketosis is achieved. Blood glucose levels are stabilized within a normal range and there is no break-down of healthy muscle tissue.

It would be difficult to make a credible argument against ketosis, which has been used so successfully among both healthy people seeking improved fitness and nutritionally fragile children with epilepsy, diabetes, and cancer. There has been speculation that ketosis can put undue stress on the kidneys (McArdle, WD, Essentials of exercise physiology. Philadelphia, PA Lea & Febiger, 1994) though few clinical studies have shown any damage.

In perhaps the highest protein intake ever studied, an adult male bodybuilder consumed an average of 2,263 calories, 71% from protein or 2.27 grams per pound for 10 weeks. His weight dropped from 168 lbs. to 139 lbs. and his body fat from 16% to 4.4%. Blood analysis found an increase in a reliable test of kidney function called “blood urea nitrogen” or BUN from 16 to 53 (normal is 6 to 25) without evidence of kidney damage. We would not advocate such high protein intake for such an extended period but it is interesting to note how much people have pushed the limits without suffering consequences.

Everyone is in some degree of ketosis all day. The most sensitive tests of ketosis (“NMR” and “blood ketone level”) show that we all have ketones under any condition. For instance, anyone off the street (not dieting or exercising, having just eaten) may have a ketosis reading of 0.003 to 0.01; most of us are up to about 50 after not eating overnight; after completing a marathon, runners have readings of over 100; in the first week of a diet (whether or not it’s “ketogenic”), the readings are around 200-300. There is no definition for the precise level that constitutes “ketosis.” Most weight control and ketogenic epilepsy or cancer treatment programs define ketosis as visible color on a urine dipstick. The problem is, we may have enough ketones in our urine to turn the stick a different color at 6:00 but not at 6:15. It is a very crude, and very transient, measurement.

Some of the benefits many people experience while in a state of dietary ketosis for intentional weight loss may include rapid weight loss, decreased hunger and cravings, improved mood, increased energy and, as long as protein intake is adequate, protection of lean mass.