Picking Your Goal Weight

Rather than picking an arbitrary number for vanity there’s a better way.  BMI may be the worse way possible (this Smart BMI page does better). Looking at pictures of other people is probably the second worse possible way. To pick your goal weight you should take these things into account –

  • Gender
  • Lean Body Mass
  • Age
  • Ideal Body Fat

Each of these can be determined fairly easily.


I’m going to assume that you know your gender although that may not be a safe assumption.

Determining your Lean Body Mass

There are on-line calculators which let you determine your Lean Body mass. Here’s one of them (US Navy Calculator – Body Fat Calculator).  For an example, I put in my current numbers:

That has my Lean Body Mass at 142 lbs and my current Body Fat percentage at 21%.

Ideal Body Fat Percentage by Age

The ideal body fat percentage can be found in various on-line charts such as (Ideal Body Fat Percentage by age) –

I am 55 years old and they have my idea body fat percentage at 20.9%. Pick your own number from above.

Goal Weight

The goal weight is the Lean Body Mass divided by (1 minus the ideal body fat percentage). For me that’s –

142 (Lean Mass from the US Navy calculator above) divided by (1 minus .209 from the Ideal  Body Fat percentage chart at my age) = 179.5 lbs

I am at 180.4 so I am within 1 lb of my ideal weight.


Not Losing Weight But Losing Inches

What about people who say that they are not losing weight but they are losing inches? The comment is often something like this:

with the increased protein intake of the keto diet, our bodies produce more muscle mass instead of fat deposits like on a carbohydrate rich diet. Muscle weighs more than fat so that would explain fat disappearing but scale numbers not changing

Maybe… Or maybe not…

Muscle is more dense (lower volume) per pound than fat (article). But gaining muscle mass is very slow. Lyle McDonald say that a young untrained male who begins training can put on as much as two lbs of muscle mass in a month. A woman can put on around half that much. So the rate that people are actually putting on muscle mass is pretty small. And unless someone is exercising pretty hard they won’t put on nearly as much. And older people will put on muscle even slower.

So the if someone is stalled for a couple of days or even weeks it’s not likely that they have put on much muscle mass in that time period. Given months, maybe they have put on some.

But this point can be answered by measuring a person’s body fat percentage.

So, there could be some muscle replacement. Or there could be loss of lean body mass. How do you tell the difference? Take measurements with a tape measure and use a calculator to determine your muscle mass.

And your own body fat percentage goals can be set based on tools like “Visualize Body Fat Percentage“. Make your goal to achieve a body fat percentage not a goal weight. The goal weight can be determined from the goal body fat percentage, etc.


Hunter Gatherers and High Protein Diets

JOURNAL OF ANTHROPOLOGICAL ARCHAEOLOGY 2, 1-31 (1983) Energy Source, Protein Metabolism, and Hunter-Gatherer Subsistence Strategies (entire paper as PDF document) JOHN D.

During late winter and spring, hunter-gatherers in temperate, subarctic, and arctic environments often relied on diets that provided marginal or inadequate caloric intakes. During such periods, particularly when stored food supplies dwindled or were used up entirely, lean meat became the principal source of energy. Nutritional problems associated with high-protein, low-energy diets are discussed. These problems include elevated metabolic rates, with correspondingly higher caloric requirements, and deficiencies in essential fatty acids. The relative benefits of adding fat or carbohydrate to a diet of lean meat are evaluated in light of the protein-sparing capacities of these two nutrients. Experimental data indicate that although both enhance high-protein, low-energy diets, carbohydrate is a more effective supplement than fat. Given the nutritional inadequacies of a lean-meat diet, the paper concludes with a discussion of alternative subsistence strategies that increase the availability of carbohydrate or fat at the critical time of year.


Metabolism and Aging

Intuitively, we all know that our metabolism slows as we age. Did you though this has been quantified? Here’s the chart of Basal Metabolic Rates in men and women vs age:

So this, at least in part, demonstrates why it is harder at 50 to lose weight than when we are 20. For a man of 20 their BMR is about 46 and the same man (at the same size) their BMR is around 38. That’s only 82% of the age at 20. So, yes, it is harder to lose weight since you have to eat less to lose weight than you did when you were young, but it is not at all impossible.

Even if you are older, you can do it.


Protein Turns into Cupcakes?

Dr Fung makes the following statement on this webpage (Why Low Carb Is High in Fat – Not Protein):

Once again, these amino acids are absorbed into the portal circulation and directed towards the liver where excess amino acids get turned into glucose.

Turns out the process is much more complicated. To be fair Dr Fung may be simplifying the process for his readers, but the process is more like this (which is probably still an oversimplification). From (Amino Acid Metabolism and Synthesis Explained):

Amino acids that are in excess of the body’s needs are converted by liver enzymes into keto acids and urea. Keto acids may be used as sources of energy, converted into glucose, or stored as fat. Urea is excreted from everyone’s body in sweat and urine.

So it is not quite as simple as Dr Fung lays it out. And keto acids are exactly the goal of any Low Carb diet, ie, the production of ketone bodies. We know that the production of glucose from ketones is necessary to feed brain cells (and some other cells) since they don’t get glucose from carbohydrates when we are on a ketogenic diet. In the absence of any dietary carbohydrates we may actually need more Protein to fuel this very path.

Are the Low Protein LCHF folks then making a serious mistake with very low levels of Protein? Are they relying on studies for necessary Protein levels where subject were not in Ketosis? I will bet a donut they are.

What is the basis for “in excess of the body’s needs”? On what timeframe? Is that per day, meal, hour?

Another Protein Experiment

I did a previous Protein Experiment where I compared the response of my Blood Sugar to 50 grams of Whey Protein vs 50 grams of Casein Protein. Since both of those were “pure” Protein with very little fat, I was curious how those results would compare to animal protein which had fat.

For this experiment I chose Chicken Drumsticks. I weighed them amount of mean (total minus bones left at the end) and the nutritional information shows them to have been close to 50g of Protein:

Here is the Blood Glucose numbers (smoothed) over several hours added to the data from the original Whey/Casein test.  The chicken drumsticks are in yellow.

Accounting for Differences

  1. The drumsticks (in yellow) are lower overall because I have been on the PSMF longer and my blood sugar levels have dropped. This is evidence, at least to me, that the PSMF is doing good things for my metabolic health.
  2. There was a dip at the start of the chicken wing experiment which was due to exercise. In this case it was a particularly grueling Saturday morning routine with a lot of lifting and burpees, etc.  That explains the drop from 72 down to 64 at the start.
  3. The highest number was very comparable to the Whey and Casein numbers in terms of rise from the minimum. The max rise in Blood Sugar in all of these cases was no more than 20 units.
  4. The slope down with the animal Protein is longer and slower. That may explain less feelings of hunger as the consumption of the Protein ends.
  5. The curve is longer than either of the “pure” Proteins. The fat may extend that longer than the pure proteins. I’d like to repeat the experiment with low fat chicken breasts and see if it’s the fat or if it is the animal Protein vs Milk Protein of the Whey/Casein choices that makes a difference.


50 grams of Protein is a decent serving size. It is more than enough to stimulate Protein Muscle Synthesis.

All in all, I see nothing to worry about with eating Protein even for Type 2 Diabetics like myself. With all of the “Protein turns into candy bars” fear mongering out there, some sanity needs to be applied to the subject.


Of course, I would encourage any diabetic to test to see where they are with this same test. At least this way they know what effect Protein would have on their body. If they are a Type 1 Diabetic this information could be helpful to determine what amount of Insulin they should add for Protein.


mPSMF – Weight Loss Progress

My modified Protein Sparing Modified Fast is moving along very well. Here’s my weight loss chart (from Cron-o-meter):

I had a nice drop over the past couple of days. Note that I started teh food diary in Cron-o-meter on Oct 24th. That may contribute to the losses due to the increased attention to intake. Before that I was using my own spreadsheet to track diet.  Cron-o-meter may be making me more accurate with measuring food intakes.

Goals Changes?

My newly adjusted weight goal is 170 lbs. That’s 144.4 lbs of Lean Body Mass and 15% body fat. That’s in the middle of the athlete range of body fat and on the low end for an older man like myself.

Modified Protein Sparing Modified Fast (PSMF)

I am calling what I am doing a Modified Protein Sparing Modified fast (PSMF) since the classical PSMF does not factor in fat oxidation rates.

I think it’s useful to factor in fat oxidation rates since that’s the maximum amount of fat a person can pull from their body per day. See my post, “Hypophagia – How much fat can I lose in a day?” for details.

Lyle McDonald’s Rapid Fat Loss Book

Lyle McDonald’s book “Rapid Fat Loss” (RFL) simply puts people on a particular amount of protein depending upon what stage of the diet a person is on. As the diet goes on and a person loses body fat their protein amount increases on Lyle’s method. So basically, his method is Very Low Carbs (except certain unlimited green veggies).

I think the fault in Lyle’s method isn’t so much that it leads to excessive protein consumption. Some would say that there’s no such thing as too much protein and within limits they could be right.

I think the fault in Lyle’s method is not factoring in the limits of hypophagia. Drop your calorie intake too low (below what the body can provide) and something has to give. If you can’t lose more than a particular amount of fat per day then why would you eat at a lower calorie amount than that?


Ideal Body Fat Percentage

The article (Ideal Body Fat Percentage Chart: How Lean Should You Be?) lists two different idea body fat percentage charts:


Note the references to Jackson, A., & Pollock, M. (1978). Generalized equations for predicting body density of menBritish Journal of Nutrition, 40(3), 497-504. doi:10.1079/BJN19780152 (Full Text).

By age (second chart) my ideal body fat percentage is  20.9%. At a LBM of 144.4 lbs, that’s:

144.4 / (1 – .209) = 182 lbs or about 10 lbs to go to that goal.



Goal Weight Calculation

I discovered that I did the calculations wrong for my target weight. Lyle McDonald has a formula on his Body Composition site:

Goal Weight = Current Lean Body Mass / (1-Goal Body Fat percentage as a decimal)

My LBM is 144.4. My Goal Body Fat percentage is 15%. So the correct goal weight is:

144.4/(1-.15) = 170 lbs

Checking it backwards, if my fat percentage is 15% then my LBM is 85%:

170 x 0.85 = 144.5 – so that’s the correct formula.

I was calculating it as LBM x (1 + Body Fat percentage as a decimal) which was a number of 166 lbs. I know it’s not a huge difference but at 190.8 lbs getting to 170 seems slightly more doable than 166 lbs.

I really like Lyle’s site. Lot of good information. And better math than my own math.