We have all heard of proteins at one point or another in our life but do we really know what they are or do? Let´s find out.
Proteins are made up of amino acids. There are 20 amino acids. These amino acids can be arranged in a million different ways to create millions of different proteins. Amino acids can be categorized as essential or non-essential. Essential amino acids are those that we cannot create through our own metabolism. Therefore we need to obtain them through foods. Non-essential amino acids are those that our body can synthesize (build). One gram of protein contains 4 calories (in comparison, one gram of carbohydrates also contains 4 calories, and one gram of fat 9 calories). Proteins are used by the body to:
- Build, strengthen and repair/ replace things, such as tissue.
- Make antibodies for our immune system.
- Make hormones.
- Muscle contractions.
- Make enzymes.
- Transport things.
- Store things .
Dietary thermogenesis (DT) is the process of energy production in the body caused directly by the metabolizing of food consumed. Consuming more protein causes a greater energy expenditure than consuming fat and carbohydrates (2) ( click here to read more). And diets high in protein are more important than the low carb or low fat component in achieving body weight loss and weight maintenance (3). This is because, higher protein diets generally help people lose less muscle and more fat at the same calorie intake. (4-7). However, after a certain point eating more protein isn´t going to help you lose any more fat. And in extreme cases it could even make you gain fat (it´s quite hard to turn protein into fat but it could happen). But with all this said, most people probably eat less proteins than they are suppossed to. Here is what is recommend by the experts (8):
- Infants require about 10 grams a day.
- Teenage boys need up to 52 grams a day.
- Teenage girls need 46 grams a day.
- Adult men need about 56 grams a day.
- Adult women need about 46 grams a day
but if you ask me, it probably woudn´t hurt if we consumed a little bit more especially if you are exercising (9)! But, I will explain that in my next blog, where I will also talk about if eating too many proteins is bad for the kidneys and how much should we be consuming.
So to summarize:
- Proteins cause a greater energy expenditure, when you metabolize them, than consuming fat and carbohydrates.
- Diets high in protein are very important in achieving body loss and body maintenance. .
- Proteins are made up of amino acids. There are 20 amino acids, that can be divided into essential and non-essential.
- 1 gram of protein contains 4 kcla.
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- Westerterp KB. Diet induced thermogenesis. Nutr Metab (Lond),2004 Aug 18;1(1):5
- Soenen S, Bonomi AG, Lemmens SG, Scholte J, Thijssen MA, van Berkum F, Westerkep-Plantenga MS. Relatively high-protein or `low -carb´ energy-restricted diets for body weight loss and body weight maintenance. Physiol Behav, 2010 Oct 10;107(3):374-80.
- Layman DK, Evans E, Baum JI, Seyler J, Erickson DJ, Boileau RA. Dietary protein and exercise have additive effects on body composition during weight loss in adult wome. J Nutr. 2005;135(8):1903-10.
- Leidy HJ, Carnell NS, Mattes RD, Campbell WW. Higher protein intake preserves lean mass and satiety with weight loss in pre-obese and obese wome. Obesity.2007;15(2):421-29.
- Layman DK. Protein quantity and quality at levels above the RDA improves adult weight loss. J Am Col Nutr.2004;23(6)
- Wycherley TP, Moran LJ Clifton PM, Noakes M, Brinkworth GD. Effects of energy-restricted high-protein,low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trials. Am J Clin Nutr.2012;96(6):1281-98.
- Source for Acceptable Macronutrient Distribution Range (AMDR) reference and RDAs: Institute of Medicine (IOM) Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. This report may be accessed via www.nap.edu
- Wolfe RR, Deutz NE. Is there a maximal anabolic response to protein intake. Nutr, 2013 Apr,32(2):309-13
Comments on: "Proteins- Part 1" (4)
Waiting for Part 2 !!!
Glad to hear that 😉
Good blog! But how about that latest study by the University of Granada saying that a hyper-proteic diet makes you more likely to have kidney problems in the future? Here is the info,
Sorry for bringing a shadow on our friends the proteins.I was a great believer of them too!
Thanks for the comment and don´t worry you can post whatever you want. Sometimes I will be wrong or the studies I mentioned are old and a new one came out saying the contrary. So, the more information the better. Now, with regards to the study you mentioned there are a couple of things I disagree with. First, in the study they were feeding the rats a diet in which the proteins represented 45 %!!! of the diet. That is a lot!! The normal recommendations are that proteins should represent just 10%, and when I mentioned in my last blog that we should increase that, (specially in people who exercised) I did not mean 45%!! Also, if you look at the literature, withing wide limits, there is no evidence that a diet high in protein has any detrimental effects on those with normal renal function .(http://www.ncbi.nlm.nih.gov/pubmed/16174292, http://www.ncbi.nlm.nih.gov/pubmed/19138405) http://www.fasebj.org/cgi/content/meeting_abstract/25/1_MeetingAbstracts/983.25) Second, I don´t know if those rats were allowed to exercised or how much. When I say, there should be an increase in protein intake, again, I am talking about people who are exercising. Couch potatoes are probably fine eating the recommend dietary guidelines for protein intake. So to summarize, I agree that if 45% of your nutrients are coming from proteins it is probably not a healthy idea (specially if you are not exercising), but a diet high in protein (withing a wide range ) should not have any detrimental effects on those with normal renal function. Those with a renal dysfunction should NOT be eating a diet high in protein! Thanks for the comment and I would love to hear your opinion on what I just said.