Taxonomy of Low Carb Studies

I’ve been collecting studies for a while and hosting them on GitHub at OpenKeto/KetoStuff. Here’s the structure of the studies.

Some of the studies can be put into multiple places so I picked one or the other place to put them without much pattern as to why. Classifying the LC Diet as Energy Input is possibly the key insight into this pattern. Also, the Effect of the Ketogenic Diet on Diabetes is under MetS.

With GitHub Desktop you can replicate the entire repository onto your computer or select individual files to download. Copyrights are the individual holders. Studies are reproduced here and were found on the Internet in general.

 

 

Crunching Data from Cronometer

In my last post I showed how to export data from Cronometer to your favorite spreadsheet. I ran my own data and got this for totals:

Item kcal percent
Energy (kcal) 434318.19
Total Protein 155395.72 35.8%
Total Fat 259107.39 59.7%
Total Carbs 33405.04
Total Fiber 13593.28
Total Net Carbs 19815.08 4.6%

This data started at the end of October last year so it has about 7 months of complete food logs.

I have to admit I am surprised that my Protein number is that high (more than 35% of calories from Protein). But following Dr Ted Naiman’s macros that puts me at a P:NPE ratio of 1.045 which is pretty much in the middle of the maintenance range. And I have been fairly stable in weight for the past couple of months.

Here’s my weight plotted across the same time span with a red trend line. I hit a new low this AM (164.1lbs).

Here’s where it gets kinda fun. I was able to plot weight vs calories. For this I used a Pivot Table and used the sums feature to get the totals for each day.

Here I have plotted the P:NPE ratio (normalized by multiplying by 100) against my scale weight hoping to see a correlation. 100 is equal grams of protein to carbs plus fat. Numbers over 100 are more protein. Numbers under 100 are less protein.

When the blue lines are high, I was doing a PSMF cut. When the blue is around 100 I was trying for maintenance. Hard to see much of a correlation there. It could be the scale is exaggerated for the P:NPE ratio compared to the weight scale but the weight seems to be taking a fairly steady drop.

Calories in:Calories Out Meets Reality

Let’s try the same thing with calories. Surely, that will show a correlation to weight change? For this one I added the light blue trend line as a polynomial and the light green line as a poly trend line poly. Calories are scaled down to 1/10th. Clearly, when I eat 1500 calories a day I lose weight a bit faster but it’s really hard to see much of any correlation between my weight and the number of calories I eat.

 

Keto Podcasts

I listen to quite a few Keto Podcasts. They can be informative and in some cases entertaining. Here’s some of them.

  • The Paleo Solution Podcast – It might seem like an odd first choice but I really like Robb Wolf’s style. He’s one smart paleo cookie. He has quite a bit of keto content and has done keto for much of his adult life.
  • 2 Keto Dudes – There’s a lot to like with these two software developers turned keto dudes. They’ve had a similar journey to mine with overcoming Type 2 Diabetes and their interview format is flexible enough for them to have guests that aren’t exactly in line with their higher-fat views. I’d like to see these guys get closer to goal weight but their reluctance to do Protein Sparing Modified Fasts (PSMF) is really slowing down their progress.
  • Keto for Normies – Her voice can be grating and his can sound like a meathead but their hearts are in the right place. They aren’t afraid to try things like PSMF or Carnivore and report on their successes or failures.
  • The Primal Blueprint Podcast is hosted by Mark Sisson, author of a famous low-carb paleo blog Mark’s Daily Apple.
  • Ben Greenfield FitnessBen Greenfield is another really sharp guy with some good insights into keto and athletic performance.
  • Keto Savage – This is the guy who ate 4000 calories a day and gained body fat.
  • Keto Geek – A good science keto show.
  • Ketodontist – An orthodontist/dentist who lives keto and has some great interviews as well.
  • Keto Talk with Jimmy Moore – It is with great reluctance that I list this podcast. Mostly I am listing it because Jimmy Moore tends to have some pretty good guests. But Jimmy’s dramatics are a bit to take at times.

The same sets of guest often make the rounds on each of these shows. They all seem to have the same list of keto guests such as Dave Feldman (Cholesterol Code), Marty Kendall (Optimising Nutrition), Shawn Baker (Carnivore Diet), Ted Naiman (Burn Sugar Not Fat),  Robert Sikes (Keto Savage), Luis Villasenor/Tyler Cartwright (KetoGains). It does also entertain me that the podcasters often interview other podcasters.

I haven’t deliberately omitted any podcasts that I know of. There’s some I have not listened to yet so if I find a new one, I will add it to this list.

 

Weight to Height Ratio = Predictor of Mortality

From this study (Ashwell M, Mayhew L, Richardson J, Rickayzen B (2014) Waist-to-Height Ratio Is More Predictive of Years of Life Lost than Body Mass Index. PLoS ONE 9(9): e103483. https://doi.org/10.1371/journal.pone.0103483):

Mortality risk associated with BMI in the British HALS survey was similar to that found in US studies. However, Waist to Height Ratio (WHtR) was a better predictor of mortality risk. For the first time, Years of Life Lost (YLL) have been quantified for different values of WHtR. This has been done for both sexes separately and for three representative ages.

 

Objections to the Keto Diet – Part 3 – Keto diets are “unnatural”

This was my favorite criticisms of the ketogenic diet by one of the dietitians. Eating meat and vegetables is somehow unnatural. Just think how twisted that is. The truth is what is unnatural is eating processed, refined food. That’s the very definition of unnatural.

This is the central point of the Paleo/Keto movement. The diet is primal. We ate meat and vegetables for most of our genetic history. Processed/refined foods came to their place in the past 100 or less years. A mere blink in our history. Is our memory so short that we don’t know what our ancestors ate?

What About Fat?

But, let me be more generous in my response. Suppose the unnatural aspect is “eating all that fat.” Guilty as charged – the Low Carb diet does use fat as the fuel instead of carbohydrates. To someone who is ordinarily carb fueled this seems like the natural state of humans.

And, eating fat would be unnatural if nature didn’t have a mechanism in our bodies to deal with dietary fat. Fortunately, we are made to live off our body fat for long periods of food shortage. Famines were common place in our history since weather shifts and some years rains don’t come.

Genesis 12:10 Now there was a famine in the land, and Abram went down to Egypt to live there for a while because the famine was severe.

In fact, what is unnatural is food abundance. That is also fairly recent in our human history. We can live for days or weeks (months if we have enough body fat) without food. The Guiness Book record holder is Angus Barbieri who went for 382 days without food on a medically supervised fast (Longest Fast Yet – Aug 2017).

We were built to survive periods without food and consume our own body fat. We all face this every single night. Our bodies shift from burning the food we eat to burning our body fat as we sleep. When we eat we break that fast (aka breakfast). There’s nothing unnatural about this at all. If it wasn’t true we could not lose body fat.

This is a key strategy I have used to lose weight. It’s called Intermittent Fasting where I stretch out that period of fat burning by skipping breakfast. It is particularly effective since the fat we eat stays in our bodies for up to 10 hours being digested and used for fuel. After that we switch to burning stored body fat.

Overshot My Recomp Goals – Part 3

Consequences for Fasting

In Part 2, I looked at the problems with low body fat.

The first obvious consequence of being low on body fat is that I can’t do any extended fasts anymore. I really liked fasting. My longest fast was 25 days with water only. I also did four fasts of 9-10 days. And a bunch of 3-4 day fasts.

I didn’t lose a ton of weigh net from the fasts. But I did learn to not be hungry and that’s a pretty big accomplishment. I wonder if that’s part of what is happening now? Does fasting break the hunger cycles? Or is it just low carb that does that?

I probably need to evaluate doing intermittent fasts. I’ve still been eating in a window. I eat a Protein meal at 11:30, another protein meal at 3:30, do CrossFit at 5:30, then eat at 7:00 PM. That’s approximately a 16:8 fast:eat window. This gives the body time to drop glycogen stores, insulin and glucose levels.

Intermittent Fasting combined with Ketogenic (Low Carb) are a killer combination. Keto doesn’t provide insulin spikes and Intermittent Fasting lowers the Insulin level even further.

In Part 4 I take a look at Eating Strategies for gaining fat.

 

 

Overshot My Recomp Goals – Part 1

I did the WVU Bod Pod this morning. Back in Oct 2017 I was at 25.3% body fat. My goal since then has been 15% body fat. Apparently I undershot that goal and I am now at 7.5% body fat. This is confirmed by my Nokia Scale when I set it in athlete mode (something I hadn’t done since I didn’t consider myself lean/athletic).
I am happy with the re-composition aspect because the test shows me gaining 8 lbs of lean body mass at the same time that I lost 36 lbs of body fat. I’ve succeeded at the recomp goal way beyond my expectations.
 
 So what’s wrong with that? See Part 2 for the risks involved with low body fat.

Understanding Weight Swings

Most dieters are stumped when they notice their weight going up and down by a couple of pounds. Here’s my last few weeks. I weigh every morning after I pee and before I take my shower. This post will attempt to explain some of the reasons for weight fluctuations.

Reasons for Weight Fluctuations

There are a lot of explanations for our daily weight swings. Some of these are probably understood by dieters, but others are more technical:

  • Salt variance
  • Caloric variance
  • Level of Hydration
  • Previous Day Exercise
  • Fecal matter
  • Glycogen Storage

Salt Variance

Salt comes in via differing concentrations in different foods. In keto, the salt from foods tends to be much less than the salt from processed/refined carbohydrate foods but there are notable exceptions like some cold cuts and cured meats. This is described here (Electrolytes, Water Retention, Low Carb Diets).

The variance in salt day-to-day will cause you to hold onto water weight until your body equalizes.

Feeling Salty? My n=1 Salt Experiment

If you are skeptical about the effect of salt on your weight, eat a jar of pickles or some ham.

A small jar of pickles has only 44 calories but 3000 mg of Sodium. A small jar of olives has 250 calories but 2600 mg of Sodium. I deliberately ate a jar of olives one day and a jar of pickles the next day and got my weight to go from 168.1 lbs to 171.1 in just two days. And that weight “gain” can’t be blamed on calories since my caloric intake on those days was below my typical energy expenditure (one of the days was 1400 calories and the other was 2200 calories). It was all about added salt.

I had about 3 cups worth of ham on Easter and went from 167.7 lbs Sunday AM to 171.0 on Monday AM. The ham had almost 5000 mg of Sodium.

Can We Eliminate Weight Variance from Salt?

It may be possible to eliminate this variance by being consistent in salt intake. I haven’t tried this so I can’t say. Does salt delivered in pickles work on a different way as the pickle gets digested than salt sprinkled on food?

It does appear that in my case it takes a couple of days for the weight gain from salt to be expelled.

There may be other connections. For an interesting account of the effect of salt on cosmonauts, see (The Connection Between Salt and Weight).

Caloric Variance

My day-to-day caloric variance is pretty wide. Here’s my last two weeks:

It may be surprising to many people, but numerically this has probably the least amount of effect. It would take over-eating by a significant amount over a long time to gain weight and it’s particularly hard to do on a day-to-day basis. Looking at the maths involved, if you ate an extra 100 calories that would at most turn into 100/3500 lbs of fat. That’s only 0.04 lbs.

Energy Expenditure Gets Up-Regulated

Your body tends to up-regulate your energy expenditure when you eat too many calories. Of course, over a long term you can over-stuff yourself constantly and get heavy – a strategy used by Strong Man competitors (Brian Shaw’s 12,000-calorie Strongman Training Nutrition Plan).

Your body can drop your metabolism when you eat too little. This is minimized with the Low Carb diet as long as you are not eating below your body’s ability to provide energy from fat (Hypophagia – How much fat can I lose in a day?). The missing calories get provided from body fat which tends to prevent metabolism from dropping.

It takes a consistent and long run at caloric decrease to drop weight. I’ve done it with Protein Sparing Modified fasting. The Low Carb diet itself tends to drop weight often due to less of a desire to overeat.

Level of Hydration

Anyone who takes their weight overnight will notice that their weight may go down several pounds from bedtime to after they pee in the morning. What you actually lose overnight is probably much less than a lb. Weight loss overnight is expelled as CO2 in your breath (Fat ‘breathed out’ of body via lungs, say scientists).

You may have noticed that if you drink a lot of water in the evening you might have to take a couple of trips to the bathroom overnight. If you get up later you may eliminate more of the water. I can be down weight on the scale on a Sunday when I sleep in late. Most of that change is water.

A Body Composition scale may attempt to make sense of this number. But try an experiment. Save up having to pee and weigh yourself before and after the pee. Record the water percentage before and after vs the weight. Your scale is probably not all that great at recording what you know is nothing but water weight.

Alcohol and Hydration

Alcohol consumption can affect hydration. I notice if I drink a fair amount one day that my weight goes down the next day. This has been studied (Alcohol. 2010 Jul-Aug;45(4):366-73. Hydration status and the diuretic action of a small dose of alcohol. Hobson RM1, Maughan RJ.).

Previous Day Exercise

Exercise can cause stress which causes the body to hang onto weight (I Just Started Exercising — Why Am I Gaining Weight?):

A new exercise regimen puts stress on your muscle fibers. This causes small micro tears, also known as micro trauma, and some inflammation. Those two conditions in your muscle fibers are the reason you may gain some weight. Your body responds to the micro tears and inflammation in two ways that cause temporary water weight gain. The first is a healing response.

“That stress and micro-tearing damage to the muscle fibers induces water retention in the body,” Dr. Calabrese explains. “There may be a small amount of inflammation around the micro tear, and your body retains fluid there to try to heal it.” These are short lived changes in the muscle.

The flip side is short term abstaining from exercising can cause water losses. Sunday is my off-day from exercise and I often see my weight drop on Monday mornings. This is a consistent pattern. Equally, Saturday workouts tend to be pretty intense and I often find myself going up on Sunday morning weigh-ins.

Don’t use this an excuse to not exercise. Just recognize that exercising can cause weight fluctuations.

Fecal Matter

There’s a delay between what we eat and what we poop. Clearly this leaves some weight in our bodies.

Glycogen Storage

When you fast overnight you are expending energy. And that energy comes largely from glycogen stores (at least more in the case of a carb burner). A fat burner (Low Carb diet person) gets more energy from fat but still has some glycogen stores.

Glycogen stores account for a very large amount of weight fluctuation. There are two reasons for this. Every gram of Glycogen is stored along with three or four grams of water held with Potassium (Glycogen Stores and Short Term Weight Loss).

The second reason is that the energy deficit required to reduce weight with glycogen as fuel is 1800 calories/lb which is less than the 3500 calories/lb for fat. So there’s a really big lever in this regard. It doesn’t take much energy to store water along with glycogen and it doesn’t take much energy to free water along with glycogen. Hence the two or three lbs you “lose” every night.

Are There Any Studies on Weighing?

There is an interesting study on weighing frequency (J Behav Med. 2017 Oct;40(5):846-853. Daily self-weighing and weight gain prevention: a longitudinal study of college-aged women. Rosenbaum DL, Espel HM, Butryn ML, Zhang F, Lowe MR.)? The study:

Daily self-weighing has been suggested as an important factor for weight loss maintenance among samples with obesity. This study is a secondary analysis that examined daily self-weighing in association with weight and body composition outcomes over 2 years among young women with vulnerability for weight gain.

Women (N = 294) of varying weight status completed self-weighing frequency questionnaires and weight was measured in the clinic at baseline, 6 months, 1, and 2 years; DXA scans were completed at baseline, 6 months and 2 years. Multilevel models examined the relationship between daily self-weighing (at any point in the study) and trajectories of BMI and body fat percentage.

Daily self-weighing was associated with significant declines in BMI and body fat percent over time. Future research is needed to examine causal relations between daily self-weighing and weight gain prevention. Nonetheless, these data extend the possibility that daily self-weighing may be important for prevention of unwanted weight gain.

What should be obvious is that it wasn’t the act of weighing that caused the loss of weight. IE, stepping on a scale probably didn’t cause the weight loss. It was the taking note of the weight on the scale that mattered.

It seems likely that these women who saw transient weight fluctuations interpreted these as an indication that they needed to reduce their caloric intake and decided to eat less. This seems like a self-corrective method. Those who didn’t weigh themselves didn’t know where they were and probably didn’t self-regulate. This was not a controlled trial and was limited to questionnaires about self weighing (an interesting PhD dissertation on self-weighing suggests some possibilities).

Weighing Strategy

If you were to eat at a 500 calorie a day deficit and all of that deficit was met from body fat (after glycogen stores are exhausted) then it would take a week to lose a pound (and there are some big assumptions here). So, even the strategy of weighing every week may not be helpful due to the fluxes from other sources noted above.

Could it might be a better strategy to record weight monthly? Weigh yourself daily and note the trends in your head but if you really want to see the direction check monthly.

Another strategy could be to fast around a particular weight. If you get above that weight then fast. That could work for some people. Make sure you have enough body fat to support a fast.

 

Type 2 Diabetes is not a Problem of Too Little Insulin

As everyone knows, Diabetes is a problem of too much sugar (glucose) in the bloodstream.

The body produces the hormone, Insulin, to counteract the glucose in the bloodstream. It does this by pushing the glucose into body cells. The pancreas is the organ that produces Insulin.

The Type 1 Diabetic

A Type 1 Diabetic doesn’t produce Insulin in their pancreas. Without Insulin from the pancreas the blood sugar levels rise to dangerous levels. The body responds to a lack of Insulin by opening up fat cells and emptying them out. That’s why Diabetes was referred to as the wasting disease.

As the caption below indicates this is the same girl with Type 1 Diabetes. The left is that girl before Insulin and the right is that same girl four months later after starting Insulin. She went from starving to looking plump.

Type 1 Diabetics will always be Insulin dependent to some degree.

The Type 2 Diabetic

Type 2 Diabetes is a completely different problem although it also is marked by high blood sugar levels. The development of Type 2 Diabetes is not a problem of too little Insulin. To the contrary, the best evidence is that is related to abnormally high levels of blood insulin. This study looked at the children of Diabetics to determine their precursors of Diabetes (Ann Intern Med. 1990;113(12):909-915. Slow Glucose Removal Rate and Hyperinsulinemia Precede the Development of Type II Diabetes in the Offspring of Diabetic Parents. James H. Warram, MD, SCD; Blaise C. Martin, MD; Andrzej S. Krolewski, MD, PhD; J. Stuart Soeldner, MD; C. Ronald Kahn, MD):

One to two decades before type II diabetes is diagnosed, reduced glucose clearance is already present. This reduced clearance is accompanied by compensatory hyperinsulinemia, not hypoinsulinemia, suggesting that the primary defect is in peripheral tissue response to insulin and glucose, not in the pancreatic beta cell.

In other words, as Type 2 diabetes progresses the body produces more and more Insulin to meet the demand. The response of the body to this increased amount of Insulin is to become Resistant to Insulin (Insulin Resistance and Insulin Sensitivity are inverse to each other). This Insulin Resistance sets up a viscous cycle where the more Insulin the body produces the more the cells resist the action of Insulin. Eventually, the pancreas can’t produce enough Insulin, but at this time it is producing many times the Insulin levels of a non-diabetic.

The truth is counter-intuitive (without the above insight). The real solution to Type 2 Diabetes is not more Insulin the body, it is less Insulin in the body.

Diabetic Medications

Enter modern medicine. There are a number of types of Diabetes Medications each with different methods of action.

Some of these types of medication cause the production of Insulin to be increased by the pancreas. But this just pushes the can down the road. Eventually the pancreas can’t keep up and it may even be damaged if pushed too hard for too long.

Other types of medications increase the ability of the cells to accept the glucose. These medications can make the problem even worse by making you fatter. Again, eventually the system will get out of control again.

Another type (Metformin) causes the liver to produce less glucose. That’s quite possibly the best and safest approach. Metformin also works unto a point when the liver overcomes the medicine and the medicine becomes ineffective.

The Dirty Little Secret

Eventually, most Type 2 Diabetics will end up on Insulin. That may start with a basal (one a day shot) but when the highs get too high that will be supplemented by bolus (meal-time) Insulin shots. Anytime a meal with carbohydrates is eaten the Insulin Dependent Diabetic will need to take Insulin. Up to 7 or 8 a day depending on how often you eat.

And the need will continue increase for Insulin to where you are eventually taking more than $100 a day worth of the medication.

So, if the problem is too much Insulin, what can we do to lower the Insulin demands of our bodies? Or are we just stuck getting sicker and sicker?

We Need a Strategy

The key to any strategy is getting the body to use less Insulin. As long as the body is producing high levels of Insulin it has a hard time unlocking fat cells for energy. This is true whether or not you are on Insulin.

Easy Natural Treatment

One easy way to reduce the amount of Insulin needed by a Type 1 or Type 2 Diabetic is to eat less carbohydrates. At a Very-Low-Carbohydrate (VLC) level of around 20 grams a day most Diabetics will not need bolus (meal-time) Insulin. And because their Insulin levels are dropping they will be able to taper down on their basal Insulin (although probably not to zero for Type 1 Diabetics).

The VLC diet works because glucose in the blood mostly comes from carbohydrates in our diet. Fat has no glucose response at all. Protein has a minimal response on glucose if kept at a reasonable level.

I Did This Myself

In my case, I was on an Insulin pump. When the Diabetes Dietary Nurse counselled me she told me that I needed to bolus (take meal-time Insulin) for carbohydrates. So when I went to a VLC diet I no longer needed to bolus for meals. Over the course of the next two weeks I was able to slowly drop my basal amount down from 50 units a day down to zero units a day.

When you drop your fasting Insulin levels your cells will then start to use its own fat. In my case, weight quickly dropped off as I kept my Insulin levels low. In the first month I lost something like 30 lbs.

Within 2 weeks of starting I was completely off the Insulin pump. I continued to take Metformin for months after that since it still seemed to have a small effect on my Dawn Syndrome (High Blood Sugars in the morning). Eventually, I was able to discontinue taking Metformin.

Intermittent Fasting

Besides a VLC diet, Intermittent Fasting (IF) was the other key to getting this to work. With IF your body is only producing Insulin in response to the narrow window of meals. With a longer time between the meals it gives the body a chance to lower Insulin levels to fat burning levels.

I did 20/4 day IF. That basically meant I skipped breakfast and lunch but had an extended dinner time-frame of around 4 hours. That gave my body 20 hours to recover from the meal and naturally drop my Insulin levels. Since I ate a VLC diet I wasn’t producing glucose from the carbs that previously were in my diet.

There is Hope for the Type 2 Diabetic

 

GNG in Fasting

From (Nutrition. 1995 Mar-Apr;11(2):149-53. Glycerol gluconeogenesis in fasting humans. Baba H1, Zhang XJ, Wolfe RR.):

The contribution of glycerol to glucose production has been measured in healthy volunteers by the simultaneous primed constant infusion of 1-[13C]glycerol and 3-[3H]glucose and the determination of the rates of appearance (Ra) of glycerol, glucose, and glycerol-derived glucose.

In the postabsorptive state [sic: after you eat], glycerol Ra was 3.11 +/- 0.44 mumol.kg-1.min-1, of which 36% was converted to glucose, accounting for 4.5% of total glucose production.

After 62-86 h of starvation, glycerol Ra rose to 5.32 +/- 0.58 mumol.kg-1.min-1, and 68% of glycerol was converted to glucose. This accounted for 21.6% of total glucose production. Glycerol Ra was closely correlated with its conversion and contribution to glucose.

These findings confirm that the contribution of glycerol to glucose production is directly correlated to its release as a consequence of lipolysis and support the notion that the central physiological role of accelerated lipolysis in fasting is the provision of gluconeogenic precursor.

If you don’t want Gluconeogenesis then stop fasting (Science 25 Oct 1991: Vol. 254, Issue 5031, pp. 573-576. Quantitation of hepatic glycogenolysis and gluconeogenesis in fasting humans with 13C NMR. DL Rothman, I Magnusson, LD Katz, RG Shulman, GI Shulman
See all authors and affiliations).

The rate of net hepatic glycogenolysis was assessed in humans by serially measuring hepatic glycogen concentration at 3- to 12-hour intervals during a 68-hour fast with 13C nuclear magnetic resonance spectroscopy. The net rate of gluconeogenesis was calculated by subtracting the rate of net hepatic glycogenolysis from the rate of glucose production in the whole body measured with tritiated glucose.

Gluconeogenesis accounted for 64 +/- 5% (mean +/- standard error of the mean) of total glucose production during the first 22 hours of fasting. In the subsequent 14-hour and 18-hour periods of the fast, gluconeogenesis accounted for 82 +/- 5% and 96 +/- 1% of total glucose production, respectively. These data show that gluconeogenesis accounts for a substantial fraction of total glucose production even during the first 22 hours of a fast in humans.

I am making this point tongue in cheek. Of course you want GNG. Otherwise you would produce nearly zero glucose and your body requires some glucose.

During fasting your energy comes from fat (The American Journal of Clinical Nutrition, Volume 60, Issue 1, 1 July 1994, Pages 29–36. Fuel and energy metabolism in fasting humans. M G Carlson W L Snead P J Campbell.).

Fuel and energy homeostasis was examined in six male volunteers during a 60-h fast by using a combination of isotopic tracer techniques ([3-3H]glucose, [2H5]glycerol, [1-14C]palmitate, and L-[1-13C]leucine) and indirect calorimetry.

Plasma glucose concentration and hepatic glucose production decreased by 30% with fasting (5.2 ± 0.1 to 3.8 ± 0.2 mmol/L and 11.8 ± 0.5 to 8.2 ± 0.6 µmol·kg−1·min−1, respectively, both P < 0.001) and glucose oxidation declined ≈85% (P < 0.01). Lipolysis and primary (intraadipocyte) free fatty acid (FFA) reesterification increased 2.5-fold (1.7 ± 0.2 to 4.2 ± 0.2 µmol·kg−1·min−1 and 1.5 ± 0.4 to 4.2 ± 0.8 µ mol·kg−1·min−1, respectively, both P < 0.05). This provided substrate for the increase in fat oxidation (from 2.7 ± 0.3 to 4.3 ± 0.1 µ mol·kg−1·min−1P < 0.01), which contributed ≈75% of resting energy requirements after the 60-h fast and increased the supply of glycerol for gluconeogenesis.

Proteolysis and protein oxidation increased ≈50% during fasting (P < 0.01 and P < 0.05, respectively).

We conclude that the increase in FFA reesterification with fasting modulates FFA availability for oxidation and maximizes release of glycerol from triglyceride for gluconeogenesis.

Follow that? Glycerol comes from triglyceride in GNG. Your own body fat puts sugar in your blood. It has to.