Can a high protein diet in bodybuilders lead to metabolic acidosis?

Can a high protein diet in bodybuilders lead to metabolic acidosis?

A fascinating new study (Kim 2011) took eight elite Korean bodybuilders whose dietary intake was analysed for markers related to the condition metabolic acidosis. Metabolic acidosis is a serious problem which can lead to an increase in the breakdown of skeletal muscle tissue, a reduction in protein synthesis and a negative nitrogen balance (meaning you are losing muscle mass).

Previous research has demonstrated that a high protein diet can lead to mild metabolic acidosis (Frassetto 1998) and worsened thyroid function which may account for the negative nitrogen balance and reduction in protein synthesis (Brungger 1997).

Could we, as bodybuilders, be unwittingly producing the exact opposite outcome to that which we seek by ingesting protein over and above what is recommended?

The participants in the trial averaged 4.3g of protein per kg of bodyweight and over 5000 calories a day (it was their offseason) and measures of various markers including nitrogen and creatinine levels was taken. The level of nitrogen in the urine and creatinine was elevated which is indicative of the fact that at this level of protein intake the body was excreting more than it would be expected to do under normal dietary conditions.

The study also investigated the level of minerals such as calcium in the urine which would expect to be considerably elevated in the presence of metabolic acidosis. In this respect, while the levels were considered at the higher end of the reference range they were far from the levels associated in cases of metabolic acidosis.

What makes these bodybuilders different?

It was theorised by the researchers that a combination of high intensity resistance training and increased potassium and calcium intakes would together act as a buffer against the possibility of metabolic acidosis in high protein consuming bodybuilders.

Take Away Message

High protein diets have been repeatedly demonstrated to be better for both weight loss and muscle gain. The fact these elite bodybuilders who were all natural athletes subscribed to this pattern of eating reinforces the prevalence of this belief in modern day bodybuilding circles. High protein diets are associated to greater satiety, an increased thermic effect, and produce an environment conducive for muscle gains. The study showed that as a population, bodybuilders can offset any potential negative effects from very high protein diets by training hard and ensuring adequate mineral intake. In this case, the bodybuilders use of vitamin/mineral supplements combined with their training served to protect them from the negative outcomes that their diets could engender in the non-exercising general population.

Further Reading

Metabolic responses to high protein diet in Korean elite bodybuilders with high-intensity resistance exercise (Hyerang Kim, Saningun Lee, and Ryowon Choue 2011)

© 2012, Reggie Johal. All rights reserved.