Is A High-Protein Diet Dangerous?
I’ve been getting a bit of flak lately about the dietary protein intake that I’ve been recommending. Somebody recently said to me that they read that we can only absorb 30g of protein per meal, so eating more is a waste. This information is false. In my research to back-up my claim, I came across an article from 2009 on the Precision Nutrition website. This article tackles the high-protein diet and hammers home the point that I’ve been trying to make: the human body needs protein; not just for muscle synthesis, but for countless other metabolic functions.
Please feel free to read the article, but to summarize:
Two studies were conducted in 2009 with respect to protein intake. Both studies showed that muscle protein synthesis was stimulated maximally in the 20-30g range, regardless of higher protein consumption rates. I assume that this is where the myth about 20-30g per sitting began.
However, before jumping to conclusions, should we consider that maybe the extra protein was actually being used by the body in other productive ways (aside from muscle synthesis)?
Look at the results from a different angle an ask yourself the following questions:
1) What else will you eat? Carbs? Remember that not only do carbs spike insulin like crazy, but they have a lower thermic effect than protein (more on this below). If you’re loading up with excessive carbs, not only will your body composition suffer, but your health will deteriorate over time due to constantly elevated blood sugar (i.e. diabetes). Fats and protein should almost always make up the majority of your caloric intake.
2) What about the other benefits?:
Increased thermic effect of feeding — While all macronutrients require metabolic processing for digestion, absorption, and storage or oxidation, the thermic effect of protein is roughly double that of carbohydrates and fat. Therefore, eating protein is actually thermogenic and can lead to a higher metabolic rate. This means greater fat loss when dieting and less fat gain during overfeeding/muscle-building.
Increased glucagon — Protein consumption increases plasma concentrations of the hormone glucagon. Glucagon is responsible for antagonizing the effects of insulin in adipose tissue, leading to greater fat mobilization. In addition, glucagon also decreases the amounts and activities of the enzymes responsible for making and storing fat in adipose and liver cells. Again, this leads to greater fat loss during dieting and less fat gain during overfeeding.
Metabolic pathway adjustment – When a higher protein (20-50% of intake) is followed, a host of metabolic adjustments occur. These include: a down regulation of glycolysis, a reduction in fatty acid synthesis enzymes, increase in gluconeogenesis, a carbohydrate “draining” effect where carbons necessary for ridding the body of amino nitrogen is drawn from glucose.
Increased IGF-1 — Protein and amino-acid supplementation has been shown to increase the IGF-1 response to both exercise and feeding. Since IGF-1 is an anabolic hormone that’s related to muscle growth, another advantage associated with consuming more protein is more muscle growth when overfeeding and/or muscle sparing when dieting.
Reduction in cardiovascular risk — Several studies have shown that increasing the percentage of protein in the diet (from 11% to 23%) while decreasing the percentage of carbohydrate (from 63% to 48%) lowers LDL cholesterol and triglyceride concentrations with concomitant increases in HDL cholesterol concentrations.
Improved weight loss profile —Research by Layman and colleagues has demonstrated that reducing the carbohydrate ratio from 3.5 – 1 to 1.4 – 1 increases body fat loss, spares muscle mass, reduces triglyceride concentrations, improves satiety, and improves blood glucose management.
Increased protein turnover — All tissues of the body, including muscle, go through a regular program of turnover. Since the balance between protein breakdown and protein synthesis governs muscle protein turnover, you need to increase your protein turnover rates in order to best improve your muscle quality. A high protein diet does just this. By increasing both protein synthesis and protein breakdown, a high protein diet helps you get rid of the old muscle more quickly and build up new, more functional muscle to take its place.
Increased nitrogen status — Earlier I indicated that a positive nitrogen status means that more protein is entering the body than is leaving the body. High protein diets cause a strong positive protein status and when this increased protein availability is coupled with an exercise program that increases the body’s anabolic efficiency, the growth process may be accelerated.
Increased provision of auxiliary nutrients — Although the benefits mentioned above have related specifically to protein and amino acids, it’s important to recognize that we don’t just eat protein and amino acids — we eat food. Therefore, high protein diets often provide auxiliary nutrients that could enhance performance and/or muscle growth. These nutrients include creatine, branched chain amino acids, conjugated linoleic acids, and/or additional nutrients that are important but remain to be discovered. And don’t forget the vitamins and minerals we get from protein rich foods.
Looking over this list of benefits, it’s hard to ignore the fact that we don’t just need protein for its effect on muscle synthesis. Since a higher protein diet can lead to a better health profile, an increased metabolism, improved body composition, and an improved training response, why would anyone ever try to limit their protein intake to the bare minimum?
In conclusion: For optimal cellular function and healthy body composition you should aim for 0.7-1g of protein per pound of body weight each day. This intake will make sure that you’re getting enough protein to reap all the benefits that this macronutrient has to offer, including but not limited to the muscle-building benefit. If you would like to lose some weight and tone up your body, try substituting some carbs for protein. It’s amazing what this small change can do!
– DW
