The impact of what we eat is a very relevant and socially important topic. What we eat affects our health and well being, yet beyond this, the topic is at the centre of a culture war. Over the years, certain foods have been labeled as “bad” for us, from fats in the 1980s to carbohydrate more recently. Now, I wish to turn our attention to protein ingestion. Not because its the only macronutrient left, but because many of the modern-day health concerns we face can be attributed to how much we eat, as well as the make up of those calories. Plus, the marketing and fitness fads almost forcing protein down people’s throats, marketing it as a dietary saviour, with claims that it can cause no harm. Of course, common sense tells us that nothing in excess will turn out to be good for us.
Hence the focus of this paper takes on the protein craze that is sweeping across society. Firstly, its worth clarifying a few points; 1) protein ingestion is required for muscle mass growth and development. Amino acids provide the building blocks for our cells, 2) eating protein as part of a balanced and healthy diet is not likely to cause any harm. These points are not new, but it’s the over consumption of protein that I am interested in. The common belief is that when we eat protein, its used for muscle mass growth, with any excess simply being removed in our urine. This is only true to an extent and offers only part of the story. Amino acids are used to make proteins, enzymes, hormones, and other important molecules. Indeed, our muscle mass is essentially the product of the delicate balance of protein synthesis (making new muscle) and protein degradation (or breakdown of muscle mass).
In addition to this, amino acid can be oxidised to produce ATP energy, which occurs in the muscle and liver. Amino acids can also be used to make #sugar (glucose), #fats and cholesterol. So here we have some basics in metabolism. When protein intake exceeds our immediate needs for muscle growth and repair, the excess can be converted into glucose and fat, both of which can be stored as energy sources for later use. However, excessive storage of these energy substrate can disrupt normal metabolic processes. For example, increased energy consumption of both carbohydrates (ref) and fats (ref) are implicated in causing insulin resistance.
Furthermore, and very important to the issue at hand, evidence also suggest that amino acids can themselves interfere with normal metabolic processes. For example, Branched-chain amino acids (BCAA) plasma concentration positively correlate with insulin resistance and predict the development of type 2 diabetes in adults with previously no metabolic issues [1]. Indeed, high plasma amino acids interfere the way insulin acts to remove glucose from the blood and into the muscle. For those that like more detail, amino acids can reduce insulin-stimulated glucose disposal in muscle via overactivation of key cellular processes including mTOR/S6 kinase pathway and reducing the activation of the insulin receptor (i.e. phosphorylation of IRS1 [2]).
In conclusion, it’s clear that protein holds a pivotal position within a balanced diet, as well as serving as a crucial component for weight management, as it can help reduce body fat and suppress appetite. High-protein diets, such as the Zone diet, aim to maintain insulin levels within a certain range (normal insulin range 2.6 - 24.9 mIU/L) to promote fat burning and weight loss. However, the effectiveness and safety of high-protein diets for long-term weight loss are still debated. In addition, excess energy intake in any form, will lead to this energy being stored. Protein is no exception and in excessive amounts, amino acids are stored in the body as triglyceride or converted to glucose by the liver. In addition, too much amino acids can interfere with important signalling processes, resulting in metabolic syndrome, weight-gain and even type 2 diabetes. For those interested in learning more, you may wish to read our review paper on this topic [3].
1. P. Wurtz, P. Soininen, A.J. Kangas, T. Ronnemaa, T. Lehtimaki, M. Kahonen, et al. Branched-chain and aromatic amino acids are predictors of insulin resistance in young adults. Diabetes Care, 36 (3) (2013), pp. 648-655
2. F. Tremblay, M. Krebs, L. Dombrowski, A. Brehm, E. Bernroider, E. Roth, et al. Overactivation of S6 kinase 1 as a cause of human insulin resistance during increased amino acid availability. Diabetes, 54 (9) (2005), pp. 2674-2684
#sugar #fats #weightloss #insulinresistance #insulin #weightloss #weightlossjourney #weightlosstransformation #protein #aminoacids #muscle
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