We know that insulin resistance is a condition that is a precursor to diabetes, but we’re still filling in the pieces as to the blood chemistry of those obese people who actually develop insulin resistance. One recent study out of Duke has found that these obese people have been found to hold onto proteins called branched-chain amino acids (BCAAs), which are found in high levels in meat products, at far higher levels than non-obese people and there’s a suspicion that these amino acids, in combination with a high-fat diet, may be contributing to insulin resistance. The team found that the BCAA signature in obese humans consisted of the branched-chain amino acids plus a cluster of several products related to the body’s breakdown processes for BCAA.
Apparently this overload causes changes at the cellular level that can lead to insulin resistance; the scientists found specifically that insulin resistance occurred in animals with a diet high in the branched-chain amino acids, but only if they were ingested along with a high level of fat in the diet. Because obese humans tend to ingest high-fat diets, the combination of high-BCAA and high-fat intake might contribute to insulin resistance in obese humans. BCAAs comprise as much as 25 % of amino acids in dietary protein, and are particularly enriched in diets high in animal (meat) proteins.
So what do we do with all of this great information? Well, the animal data suggest that there is nothing wrong with obtaining protein from sources that are high in branched-chain amino acids, as long as you are not eating beyond what your energy needs are, meaning, if you add a lot of unneeded protein to a fatty diet, perhaps that’s where you get into problems. So either you burn up the fat and use the protein for muscle building in the gym, or follow the old rule of thumb: eat everything in moderation.