StudyRepo

Meta-analysis about the amounts & role of protein required to sustain lean body mass. "∼32–46 g of high-quality dietary protein/day is reported to be required to maintain protein balance (2). This is considerably less than amounts of protein reportedly consumed by American adults (∼65–100+ g/day)" The remaining protein is deaminated, turned into glucose, and oxidized as fuel. Many studies report that, despite this, feeding protein does not seem to increase blood glucose. This study fed doubly-labeled protein from whole eggs and traced how much of the glucose entering the bloodstream during the following 8h came from this protein. It ended up being only around 4%. It therefore seems that the process of gluconeogenesis is highly regulated, it's not that "excess protein automatically gets turned into glucose and dumped in the bloodstream."

In this Brazilian 27-day RCT, protein restriction had nearly the same effect on weight loss & glucose control as caloric restriction.

Having previously established the positive effects of protein restriction, and having narrowed it down to BCAA restriction, this experiment sought to test which of the 3 BCAAs is mediating the effect. It turned out to be mostly isoleucine, with valine playing a smaller role. FGF21 was shown to be part of what mediated the effects of isoleucine restriction.

The article reviews the literature about the Randle cycle and mitochondrial inertia, and develops a model to explain how lipids and BCAAs play together to promote insulin resistance. A literature review shows that BCAAs are associated with insulin resistance and diabetes more than any other metabolite studied. Yet the negative effects of BCAAs only seem to show up in "high-fat" diets. The authors therefore believe that BCAAs can "clog up" the TCA cycle similarly to lipids, possibly competing for similar pathways. This can then lead to glucose intolerance.