Nutrition for Weight Loss
The Facts About Protein

Protein in food is made up of chains of different combinations of twenty amino acids. Eight of these amino acids your body can't live without and can't manufacture (termed indispensable amino acids). Your body needs to be provided with these amino acids from food, and the best way to do this is to eat foods high in protein.

I find it interesting that most of these amino acids actually come from plant sources, which we obtain either by directly eating the plant, or by eating the meat of an animal that has eaten the plant.1

What happens to protein once we eat it ?

Once our bodies actually receive different proteins, the body breaks them down into their different component amino acids and then uses them as biological building blocks to re-make new amino acids and new proteins for use throughout the body. When this occurs, the amino acids are transported into the bloodstream using specific carrier molecules. There appears that amino acids compete with each other to be taken into the bloodstream and then transported to areas of the body where the specific amino acids are needed. In such cases where protein supplements contain alot of the same amino acids, the amino acids in excess are taken up, while other essential amino acids may be left behind. 2

How much protein do we need in our daily diet ?

Men need about 40 - 50 grams of protein each day and women require somewhere between 36 - 40 grams per day.3,4 When more protein is consumed than is necessary (amino acids can't be stored !) the amino acids are broken down and used to produce fatty acids, glucose, urea and body heat.

Excess protein consumption is not generally deemed to be harmful, as the by-products can be expelled through urine, but may cause the body to expel a higher rate of calcium than is absorbed 5, and may also lead to kidney problems.

Both Saxelby (AUS) and Barasi (UK) report that the average diet includes up to 100 grams per day of protein. The likelihood that protein deficiency is occurring is very small. Having said this, there are circumstances where protein deficiency can still occur. When people are hospitalised over long periods of time, protein deficiencies can result from a number of factors such as lack of appetite. Very overweight people also can be prone to this which often results in their overall size masking the gradual muscle wasting within their bodies. Careful monitoring by a health practitioner is necessary in cases such as this.

So what do our body's use proteins for ?

Different types of proteins play many different roles within the body and these range from enabling blood clotting, acting as catalysts for the millions of chemical reactions that occur within the body every day, helping to maintain the body's immune system and of course maintaining the health and structure of the body's cells.

Our bones, muscles, connective tissues, blood cells and organs all have proteins within them. Without a good source of the essential proteins in our body, bone structure, muscles and vital organs will undergo wasting.

How do we make sure we're getting the right protein and amino acid mixtures ?

Our body requires a constant supply of the eight essential amino acids, because amino acids are either broken down to make other amino acids and proteins, or used to produce glucose (gluconeogenesis) for energy and the rest becomes waste excreted in the urine. So, in order for our bodies to maintain the above functions, we need to consume regularly, at least the eight essential kinds of amino acids which cannot be manufactured by the body. These eight essential amino acids are isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.4 Having said this, other amino acids can become essential in times such as a burns trauma or when a woman becomes pregnant.

Proteins from plant foods will tend to have a lower amount or not include one of these essential amino acids, and will not be as digestible as animal foods. Whole eggs and human milk provide the best match to our amino acid needs.

The table below shows which foods contain these eight essential amino acids:

Isoleucine	Many meats, fish and cheese
Leucine	Poultry, red meat and dairy
Lysine	Fish, meats, dairy and wheat germ
Methionine	Found in most foods, with high amounts in whey proteins in diary 6
Phenylalanine	Many meats and dairy
Threonine	Most meats, nuts, beans, wheat germ and seeds
Tryptophan	Small amounts found in meat, eggs, dairy and some nuts and seeds
Valine	Common in most foods

Source: AFPA Fitness

Does eating more protein help to create and maintain muscle mass ?

Now this is where it gets interesting ! There are those that say, creating and maintaining muscle mass depends on what you eat, and there are some that say, it depends on your training.

I consulted my basic nutrition textbooks, and they are in general agreement, that a higher intake of protein, has no beneficial effects on increasing or maintaining muscle mass.

Simply eating more protein, essentially will not help to increase muscle mass, with the exception of times where protein deficiency exists, increasing protein intake can help to repair and maintain muscles. If one of these essential amino acids are not included in the diet, protein synthesis will be slow and can in some prolonged cases lead to muscle wasting as seem in poor countries where malnutrition is common. There may only be a benefit to eating more protein, if the quality of your protein intake is poor, or if your protein intake is deficient. So eating the above foods, can do a lot to creating muscle mass if you have very little muscle mass.

Barasi (Principal Lecturer in Nutrition at the University of Wales Institute) in her book states that exceeding 2 grams of protein per day gives no advantage to building muscle, and may actually compromise carbohydrate intake (page 297). Wahlqvist agrees, pointing out that the recommended daily intake of 0.75 grams per kilogram, per day has already allowed for a margin of safety.

However he does comment that a normal diet that is low in fat, can achieve similar levels of protein and that branched chain amino acids, such as leucine, isoleucine and valine have a "building up" effect on muscle mass. (page 329)

So foods such as eggs, dairy and red meat which include proteins made up of amino acids like leucine, isoleucine and valine could all help to build muscle, however, primarily, it is the training that many athletes do, that increases the size of muscles, their strength and capacity.(Barasia, p.297)

More recent research seems to be suggesting however, that high protein intakes may be beneficial. A recent work published in the JACN found that the consumption of milk by untrained male participants, was associated with an increase in body weight and fat free soft tissue.7.

Lambert et. al., wrote in his paper designed to set down macronutrient nutritional design for bodybuilders, that a higher intake of protein at 30% of the total energy intake "will reduce lean mass loss relative to a lower protein intake (approximately 15% of energy intake) during energy restriction. The higher protein intake will also provide a relatively large thermic effect that may aid in reducing body fat." He sets down quite specifically the dietary requirements for bodybuilders, which I'll quote directly for you here.

" In both the off-season and pre-contest phases, adequate dietary carbohydrate should be ingested (55-60% of total energy intake) so that training intensity can be maintained. Excess dietary saturated fat can exacerbate coronary artery disease; however, low-fat diets result in a reduction in circulating testosterone. Thus, we suggest dietary fats comprise 15-20% of the body builders' off-season and pre-contest diets. Consumption of protein/amino acids and carbohydrate immediately before and after training sessions may augment protein synthesis, muscle glycogen resynthesis and reduce protein degradation. The optimal rate of carbohydrate ingested immediately after a training session should be 1.2 g/kg/hour at 30-minute intervals for 4 hours and the carbohydrate should be of high glycaemic index. In summary, the composition of diets for body builders should be 55-60% carbohydrate, 25-30% protein and 15-20% of fat, for both the off-season and pre-contest phases. During the off-season the diet should be slightly hyperenergetic (approximately 15% increase in energy intake) and during the pre-contest phase the diet should be hypoenergetic (approximately 15% decrease in energy intake)."8

Now while you may not be a bodybuilder, or even an aspiring bodybuilder, you can still derive something from this. That is, that bodybuilders do not eat high protein diets all year round, they alter their diets depending on whether they are coming into, or going out of a competition phase. High protein diets are backed by some evidence to suggest that while they can provide an increase in muscle mass and strength, and reduce body fat, may not be beneficial in the long term. There is significant evidence to suggest here, that eating a higher than usual protein diet may help in burning fat and building muscle, but exceeding 2 g/kg/day may not yield any benefit.

So, eating more protein can help to a certain degree, but eating protein to the exclusion of carbohydrates is not healthy, and may cause unwanted side effects, such as calcium deficiency and kidney problems. Eating healthily, and including eggs, milk, red meat, fish and poultry regularly will ensure that you are giving your body the right amount of amino acids that it needs to function properly.

References:

1. Barasi (1997) Human Nutrition Oxford University Press. Page 60

2. Barasi (1997) Human Nutrition Oxford University Press. Page 62

3. Barasi (1997) Human Nutrition Oxford University press. Page 71, 73

4. Saxelby (2002) Nutrition For Life Hardie Grant Books, Page 16, 17

5. Wahlqvist (2002) Food and Nutrition Allen and Unwin. Page 223, 431

6. Hinrichs J. Mediterranean Milk and Milk Products. Eur J Nutr. 2004 Mar;43 Suppl 1:I/12-17.

7. Rankin JW, Goldman LP, Puglisi MJ, Nickols-Richardson SM, Earthman CP, Gwazdauskas FC. Effect of post-exercise supplement consumption on adaptations to resistance training. J Am Coll Nutr. 2004 Aug;23(4):322-30.

8 Lambert CP, Frank LL, Evans WJ. Macronutrient considerations for the sport of bodybuilding. Sports Med. 2004;34(5):317-27.

Wishing you much health and wellness