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