Excess Protein and Fat Storage – Q&A

sQuestion: I have done a lot of study in diets and nutrition but to this day I have not been able to get any concrete evidence on what happens with excess protein in the body and I’m hoping you can help.

To make things simple, lets take a theoretical diet consisting of 5000 calories of pure protein for a 60kg, 175cm female.

Many people claim that excess protein will get wasted while others say that all excess calories eventually end up being stored as fat.

I have done my own research on the breakdown of protein into amino acids and I understood it as: some of the amino acids are wasted while others will go through the cycle of conversion and will still be used by the body for energy.

Answer: Ok, first things first.  The example given above is absurdly non-physiological.   The satiating power of protein would make such a high protein consumption impossible.  That is, 5000 calories of pure protein is 1250 grams of pure protein.  Can’t be done.  Beyond that, while the biochemical pathways for the conversion of protein to fat do exist in humans, the likelihood of it ever happening in any but the most absurdly non-physiological circumstances are effectively nil.

Let me put this in perspective.  Despite a lot of claims to the contrary, the actual conversion of carbohydrate to fat in humans under normal dietary conditions is small approaching insignificant (a topic I discussed at least briefly in Nutrient Intake, Nutrient Storage and Nutrient Oxidation).

Make no mistake, the conversion of carbs to fat (a process called de-novo lipogenesis or DNL) can happen but the requirements for it to happen significantly are fairly rare in humans under most conditions (to discuss this in detail would require a full article, interested readers can search Medline for work by Hellerstein or Acheson on the topic).


A Quick Look at Food Allergies and Intolerances

In recent year, a lot of ideas have become strangely popular on this place that we call the Internets, one of those is concern over various food allergies and intolerances.  As I’ll discuss below, not only are true food allergies and intolerance two totally different things, there is a lot of nonsensical information being thrown around about food allergies.

What seems to have happened is that one person stated that certain ideas were true and a bunch of people who didn’t know any better simply started repeating those ideas until they became an accepted ‘truth’.  Unfortunately, science says different and that’s what I’m going to look at.

The most common one that seems to be constantly repeated is that if you eat the same food (usually protein since most true food allergies are caused by proteins) continuously, you can give yourself an allergy to that food.  This happens to be utterly wrong as I’ll show below.

There are other silly ideas, one of the dumbest I’ve seen of late is that you can cure a food allergy by not eating that food for 6 weeks.  This is not only wrong but potentially fatal.  True food allergies (again, I’ll discuss what this means in a second) never go away; if someone has a true allergy to a food, they can’t ever eat that food again for all practical purposes.

Actually, that’s not entirely true, one weird study showed that children with peanut allergies could eventually get to where they could eat half a peanut but it took months and months of feeding them like 1/4 peanut to get them to that level.  Hooray.  For all practical purposes, a true food allergy never goes away and the idea that abstaining from that food will make it go away is simply absurd.

Since most food allergies occur in response to protein foods, I’m actually going to simply be excerpting the section from The Protein Book about food allergies and intolerances.  For anybody who’s interested, I’ve included the references cited in this section at the end of the article.


Fish Intake and Mercury

Fish has long been a part of athletic and other ‘healthy’ diets and there are many many reasons for that to be the case.  In no particular order, here are a few:

Fish is a high-quality animal protein which is generally readily available and (depending on location) fairly inexpensive.  As well, low-fat fish (canned tuna has been a stable for athletes and bodybuilders for decades) are nearly fat free and, as it turns out, even the fattier cuts of fish contain a large amount of ‘healthy’ fats in the form of the omega- 3 fish oils.

As I mentioned in What are Good Sources of Protein – Amino Acid Profile Part 1, some work has also suggested that the high taurine content of fish may improve insulin and/or leptin sensitivity.

All of these factors add up to fish being a good choice of proteins.

However, at the same time, not all is good in the land of fish.  An issue of some concern has to do with the mercury content of fish.  Mercury, as I imagine most know, is a toxic metal compound that, when it accumulates in the body, can cause a lot of problems.

A question that comes up often enough to be worth addressing is just how much fish can be consumed on a daily basis to get the benefits of it as a protein source while avoiding potential issues with mercury.

To address this, I’m simply going to excerpt the section on fish from Chapter 10: Whole Food Protein of The Protein Book where I examine fish protein and the issue of mercury content.

As you’ll see, depending on the type of fish in question, mercury can range from non-detectable to very low to exceedingly high.  And given the recommendations (at the end of the article) for daily limits to mercury content, it becomes clear that while some fish can be consumed in significant amounts daily, others are limited (e.g. 4-5 oz of canned tuna per day is about the limit even if bodybuilders and athletes often eat far more than that) and others exceed daily intake recommendations by far.


What Are Good Sources of Protein? – Wrapping it Up

Ok, so this series got a little out of control; what can I tell you, I have a lot to say on the topic of dietary protein as a function of having written The Protein Book.

I’ve covered a lot of information ranging from the somewhat technical/theoretical (speed of digestion) to very practical (micro-nutrient content, fatty acid content) in an attempt to answer the question what are good sources of protein?

In this final part, I want to cover a few other issues that go into answering that question (that didn’t require a full-blown article of their own) and then I’ll finish by presenting a summary table where I’ll attempt to put everything from this entire series into a comparable perspective.

In What Are Good Sources of Protein – Introduction, I included a short list of other important factors such as effects on appetite and blood sugar that I already addressed in previous parts of this series so I won’t touch on them here.  The issues I do want to touch on are availability, the actual protein content, and cost.



It should be obvious that whether or not a given protein source is good or not doesn’t matter if someone can’t get it.  The ease of availability of a given protein in a given location is clearly an issue but not one I can speak to except in the most general of terms.  What I have access to in the US has no bearing on what someone overseas can or cannot get; in fact I’m quite sure I’ve left out certain whole food protein sources simply due to being located in the US.  What someone might have access to in Norway might not be available here and vice versa.


What Are Good Sources of Protein? – Dietary Fat Content

Having looked at a few key micro-nutrients (iron, zinc, B12, calcium) in What are Good Sources of Protein – Micronutrient Content, I want to move towards the wrap up of this series by looking at another issue of importance in choosing protein sources.  That issue is the dietary fat content.

Now, without going into a lot of detail, but due to some more ‘fringe’ nutritional groups in the Internet, I suspect many will disagree with this article.  The reason is that some groups have decided that 40 years of nutritional research is flawed and biased, that the current beliefs about fatty acid intake and health are exactly the opposite of the truth, etc, etc.

When and if I ever bother to address such points (it’s usually about as useful as responding to the anti-milk people), I’ll go into more detail about this.  For now, I won’t except to say that I find both extremes of the argument to be flawed.

Saturated fat isn’t the killer nutrient that some make it to be, nor is it healthful and beneficial; the truth, as always lies in the middle and whether a high fat intake or a particular type of fat is good, bad or indifferent depends on the context.  The rest of the diet, activity, body-fat stress, etc. all determine what is good, bad or otherwise.  For more details, I’d refer readers to my two part article Carbohydrate and Fat Controversies where I go into detail as to my take on a lot of this argument.

And with that out of the way, let’s get started.


A Primer on Fats with a Bit on Cholesterol

There is often a lot of confusion regarding the issue of dietary fat not the least of which is a common misunderstanding between the issue of dietary cholesterol and dietary fat.  Simply, cholesterol and dietary fat are completely distinct chemical compounds. The confusion, mind you, came out of the early research dealing with diet, dietary cholesterol, dietary fat intake, and blood cholesterol levels.