Tuesday, August 28, 2012

Protein Is Essential, But Too Much is Too Much

Why do I consider protein the important focus for the short and long-term?

In a word, it's satiety.

That and animal based protein is nutrient-dense; when in included at adequate levels in your diet, it is much easier to meet nutrient needs each day.

Most calorie restricted diets not only reduce calories, they significantly reduce protein intake. I think this is the cause of the hunger often reported once an individual is into their lower calorie diet after a few weeks. While starvation does work in the short term, long-term 95% of people who lose weight will gain it back within three years, 99% will within five.

When you do not eat enough protein, you are starving, slowly but surely; and that holds true even in a state of excess calorie consumption.

Protein is a really neat macronutrient, not only does it provide us with essential amino acids, it also is used throughout the body to repair and build muscle, cells and tissue. Amino acids are critical to maintain our health, but they're not really a great energy source - when the body's energy sources are low, it begins to degrade proteins for use as an alternative energy source. Amino acids can be classified as glucogenic or ketogenic.



Glucogenic amino acids can be degraded to pyruvate or an intermediate in the Krebs Cycle. They are named glucogenic because they can produce glucose under conditions of low glucose. This process is also known as gluconeogenesis, or the production of "new glucose." Amino acids form glucose through degradation to pyruvate or an intermediate in the Krebs Cycle. The intermediates can then be converted to oxaloacetate, the main precursor for gluconeogenesis. (glucogenic amino acids: alanine, cysteine, glycine, serine, threonine, tryptophan, asparagine, aspartate, phenylalanine, tyrosine, isoleucine, methionine, threonine, valine, arginine, glutamate, glutamine, histidine, and proline).

In contrast, ketogenic amino acids can produce ketones when energy sources are low. Some of these amino acids are degraded directly to ketone bodies such as acetoacetate (leucine, lysine, phenylalanine, tryptophan, and tyrosine). The other ketogenic amino acids can be converted to acetyl CoA. Acetyl CoA has several different fates, one of which is the conversion to acetoacetate. Although not a preferential energy source, acetoacetate can be metabolized by the brain and muscle for energy when blood glucose is low and acetoacetate cannot be used in gluconeogenesis, since acetyl CoA cannot be converted directly to oxaloacetate.

The above is what happens when you consume adequate protein each day. So, what happens if you consume too many calories and/or too much protein? Basically, when energy sources are high, both glucogenic and ketogenic amino acids are converted to fatty acids through the intermediate acetyl CoA. Other amino acids that are degraded to intermediates in the Krebs Cycle are siphoned off into the production of urea, a nitrogenous carboxyl compound that is filtered through the kidneys and secreted in the urine.

Put another way, you now have fatty acids that can store as body fat.

It is for this reason one should not consider a low-carb diet as an all-you-can-eat buffet, just hold the carbs. Whether you're new to carbohydrate restriction, or a long-term veteren, you need to know how much protein you need at minimum, and also understand where the maximum is for weight loss and weight maintenance.

How does one know how much is enough and how much is too much?

It depends largely on weight. In fact, it is really all about how much one weighs. Protein requirements are based on body weight because body weight takes into account mass, lean body tissue and structural maintenance. The more you weigh, the more protein you need; the less you weigh, the less you need.

The absolute minimum, to meet EAA requirements is considered 0.8g/kg body weight. On a low-carb or carb-controlled diet, one does require more to fuel gluconeogenesis and most agree that protein requirement ranges, from 1.0g/kg to 1.5g/kg. A good middle maximum is 1.2g/kg if someone is active. For this reason, I usually provide individuals with a minimum target for protein each day based on the EAA minimum (0.8g/kg) from animal foods, then provide a range of maximum from all sources, including the vegetables they'll consume, that ranges 1.0g/kg and 1.2g/kg. In the years I've helped people understand how much protein is enough, I've only encountered a couple who were very active and could consume 1.5g/kg.

The chart below provides protein requirement and upper protein range for those restricting carbohydrate in their diet.

WEIGHT
PROTEIN
EAA MIN
PROTEIN
GNG RANGE
350-plus
125g
160-190g
340
123g
154-185g
330
120g
150-180g
320
116g
145-175g
310
113g
140-170g
300
109g
136-165g
290
105g
131-160g
280
102g
127-155g
270
98g
122-150g
260
95g
118-145g
250
91g
114-140g
240
87g
110-135g
230
84g
105-130g
220
80g
100-125g
210
76g
95-120g
200
73g
90-115g
190
69g
86-110g
180
66g
86-100g
170
62g
77-95g
160
59g
72-90g
150
56g
70-85g
140
55g
70-85g
130
55g
70-85g
120-less
55g
70-80g

10 comments:

  1. Isn't there a big difference in EAA and the protein listed on the label? Also, most calorie counters don't list EAAs. Do you use a rule-of-thumb ratio or something else?

    ReplyDelete
    Replies
    1. EAA is complete in most animal products. I usually suggest targeting the minimum above as your animal sources and the rest from whatever else you eat, including more animal foods.

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  2. Animal based foods contain all the EAA's in good ratios, so if you eat the minimum protein for your weight (EAA minimum above) from animal based foods (meat, poultry, game, fish, eggs, cheese) you're going to be well within range for EAA requirements. The higher total above is from all sources, including vegetables, nuts, etc. since each of those has "limited" proteins - that is one or more EAA is off in ratio to meet EAA.

    Basic rule of thumb is to divide grams of protein for EAA (minimum above) by 7 and that should give you an approximate number of ounces of meat, poultry, fish, eggs and cheese to eat (eggs = 1 ounce meat). So if you're minimum protein to meet EAA is 80g, that translates to about 11.5 ounces of meat, fish, eggs, cheese a day.

    ReplyDelete
  3. If one wanted to increase muscle mass Regina, how much more would one want ABOVE the GNG range? FE: Let's say you wanted to add 10 pounds of lean mass. How much more protein per day would be required? Since we can't know the rate of synthesis exactly, what do you think is a good ball-park figure?

    ReplyDelete
  4. Great post Regina. Q: If one wanted to increase muscle mass, how much more protein would one want ABOVE the GNG range? FE: Let's say you wanted to add 10 pounds of lean mass. How much more protein per day would be required? Since we can't know the exact rate of MPS, what do you think is a good ball-park figure?

    ReplyDelete
    Replies
    1. Data in various studies find no real benefit to go above 1.5g/kg body weight.

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  5. Regina - what is someone is an obese 300 pounds and should weigh lean 120? How do you figure the protein - for what they WEIGH or, what they should weigh?

    ReplyDelete
    Replies
    1. One needs protein based on current weight, so someone who weighs 300 would target eating at least 109g a day, with a range up to 136-165g. As they lose weight, they reduce protein to match their current weight. If they don't want to reduce protein along the way, if they target say 110g (basic minimum), they don't need any adjustment until about 220....by then only adjust IF they're still eating that much protein - a person's intake usually will fall slowly over time, it's darn hard to eat excess protein.

      Delete
  6. Anonymous6:53 PM

    great post. do the weights you refer to for the protein (e.g. 110oz per day) raw weight or cooked weight?

    ReplyDelete
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    ReplyDelete