Bodyrecomposition Mailbag 3

So another dig into the mailbag to save myself having to think of another feature article to write.  The three questions today have to do with fat loss and muscle sparing, phosphatidylserine, cortisol and water retention.   Finally is a look at causes of a plateau in weight gain.

Dietary Deficit and Fat Loss when Muscle Sparing is the Same

Hi Lyle. A nerd question: Since the only two things in human body which can: 1. store energy 2. be able to gain and loss in a huge range all year long (compare to glycogen which could only be gained and lost in a small range), are fat and muscle (is that ture?). So is that true all diet would result in exactly the same amount of fat loss, if 1. the deficit is the same and 2. the muscle loss or protection is the same? Ignoring all other factors like insulin level?


Short answer: yes-ish and I say that as I’m going to actually address a question that you didn’t actually ask.

Sort of by definition if the total actual tissue loss is the same and lean body mass (LBM) sparing is identical, actual fat loss will be the same.  It has to be.  If 10 total pounds of tissue is lost and both diets only allow 1 pound of LBM loss, the other 9 lbs has to be fat (ok, something truly screwy could go on such as loss of bone or organ mass but it’s usually pretty small).

Now, if you want to be pedantic and look at weight loss, this isn’t necessarily true.  This is why I was using the odd term tissue loss.  Because part of total weight loss is not actual tissue loss but things like glycogen, water, food in the gastrointestinal tract and such.  Those will vary depending on diet, a low-carbohydrate diet will cause glycogen to become depleted, water and minerals to be lost and since carbohydrates are the primary source of the food residue that comes out the other end, that will also be decreased. Ketogenic diets may cause a loss of water weight of 1-15 lbs in the first several days for example.