Athlete’s Blood Sugar Study – Part 2

In my post (Looking Closer at the Athlete’s Blood Sugar Study) I took a quick look at this study (Felicity Thomas, BE(Hons), Chris G. Pretty, PhD, Thomas Desaive, PhD, and J. Geoffrey Chase, PhD. Blood Glucose Levels of Subelite Athletes During 6 Days of Free Living. J Diabetes Sci Technol. 2016 Oct; 10(6): 1335–1343.)

Let’s do a deeper dive on the data and see what trends we can detect. Fortunately, at least some of the data was published:

BMI vs Fasting Blood Sugars

First, let’s test the question of the correspondence of Fasting Blood Sugar levels and BMI.

There was a linear association between the Fasting Blood Glucose (FGB) and Body Mass Index (BMI). The R^2 was small, at 0.12. The BMI range of these individuals was also less than a typical population since they were athletes.

Reference: Regression Analysis: How Do I Interpret R-squared and Assess the Goodness-of-Fit?

Fasting Blood Sugar vs Body Fat Percentage

Looking at Body Fat Percentage vs Fasting Blood Sugar shows a similar correlation to BMI. The R^2 value of 0.15was similar to the BMI value.

Fat Free Mass vs Fasting Blood Sugar

So does having a larger fat free mass help with fasting blood sugars?

Unfortunately this goes the wrong way. Rather than leading to a lower blood sugar more fat free mass leads to higher blood sugar but with the same R^2 number of 0.14.

Fasting Blood Sugar vs Fasting Insulin Secretion

There is a negative correlation between Fasting Blood Sugar and Fasting Insulin Secretion.

This is also a weak correlation with an R^2 of 0.056. Although the individuals had higher fasting blood sugars they also produced less insulin in the fasted condition.

Fasting Blood Sugar vs Post-prandial Insulin

Fasting blood sugar showed the largest correlation to post-prandial Insulin levels with an R^2 of 0.56. Individuals with poorer blood sugar control produced more insulin than others.

Fasting Blood Sugar vs Age

Although age is often viewed as central to a loss of control of blood sugar, in this group the association was not present in this data set.

Exercise Amount per Day vs VO2max

I’ve often wondered how well the amount of time a person exercises each day affected their VO2max number. There’s a small positive correlation between the two. The R^2 was only 0.11.

Fasting Blood Glucose vs Glucose Time in Band

Glucose Time in Band was the percentage of the time that blood sugars were within the “good” range.

There was a relatively strong negative correlation between the time fasting blood glucose and the Glucose Time in band. The R^2 value was 0.74.

This leads me to conclude that fasting blood sugar numbers were a good indicator of the glucose time in band.

Looking Closer at the Athlete’s Blood Sugar Study

In Heart Rate Training – Part 9, I took a look at a really interesting 2016 study on Blood Sugar levels in athletes (Felicity Thomas, BE(Hons), Chris G. Pretty, PhD, Thomas Desaive, PhD, and J. Geoffrey Chase, PhD. Blood Glucose Levels of Subelite Athletes During 6 Days of Free Living. J Diabetes Sci Technol. 2016 Oct; 10(6): 1335–1343).

The study looked at ten athletes and their blood sugars. They discovered that four of the ten athletes were pre-diabetic. Let’s take a look and see what additional information we can tease from the data.

The study had three females and seven males.

All but 4 participants consumed on average an amount of carbohydrate that was between 45 and 65% of their recommended daily calorie intake.

Ath05, Ath07 and Ath09 have elevated fasting glucose within the prediabetes range 5.6-6.9 mmol/L suggested by the ADA.

The mean PPGR ranges from 0.2 to 2.0 mmol/ displaying a wide range intra and inter of carbohydrate sensitivity.

Fortunately, they included some of the data on the participants.

Subject Sex Age BMI PBF (%) FFM (kg) FBG (mmol/L) FPI (mU/L) FIS (mU/L.min) TIB-MR (%) Mean PPGR (mmol/ Mean PPG (mmol/L) Exercise (min/day) VO2max (mL/kg/min)
Ath01 F 23 21.6 25.3 45 5.2 9 1319 86.6 1.1 6.1 84 39
Ath02 M 23 21.9 5.1 6.3 913 90.7 0.5 6 41 60
Ath03 M 50 26.4 4.7 11.8 1878 76.1 1.9 6 68 39
Ath04 M 23 20.4 5.1 64.8 4.6 6.5 832 99.2 0.5 5.5 93 67
Ath05 M 28 24.2 14.1 60.6 6 6.3 820 30.7 0.9 6.8 158 59
Ath06 M 36 22.4 15.5 63.3 4.4 8.3 1844 94.3 1.2 5.9 28 59
Ath07 M 37 26 19.7 65.3 6.7 10.5 1553 23.9 1.1 7.1 20 42
Ath08 M 22 24.5 13.2 70.6 5.5 11 1550 31.7 0.2 5.5 24 37
Ath09 F 37 21.1 17.8 46.7 6 6 936 9.7 2 7.4 102 47
Ath10 F 27 22.2 28.3 47.7 5.2 9.5 1344 86.6 1 6.7 42 44
  • FBG, fasting blood glucose;
  • FFM, fat free mass;
  • FIS, fasting insulin secretion;
  • FPI, fasting plasma insulin;
  • Maxppg, maximum blood glucose value reached after a meal; PBF, percentage body fat;
  • PPG, blood glucose value 2 hours after a meal;
  • PPGR, postprandial glucose response;
  • TIB-MR, time in band, with meals removed.
  • Body composition analysis results were not available for Ath02 and Ath03, hence PBF and FFM values are missing.

Ath03 – Unique Case

Let’s focus in on Ath03. This athlete is a 50-yr old male who has a good fasting glucose number at the same time as a high fasting Plasma Insulin and high fasting Insulin Secretion number. As the paper states:

A subject can achieve good overall control or even experience low BG, such as Ath03, but still demonstrate a high mean PPGR indicating a high sensitivity to carbohydrates.

Here is a really interesting note:

Ath03 consumed on average ~150 g of carbohydrate less than the lower recommended limit, 1770 kcal less than required (Table 2) and was the only participant to demonstrate a significant amount time below 4.0 mmol/L.

The study stated:

Athletes are traditionally encouraged to consume high carbohydrate diets to replenish muscle glycogen stores and improve performance, with a particular focus on postexercise carbohydrate consumption. However, this advice may be negatively impacting the blood sugar levels of athletes predisposed to have a low tolerance of carbohydrates.

This is exactly my concern. Are weekend warriors fueling themselves as if they are elite athletes and suffering metabolic damage as a result?


Turmeric and Curcumin for Osteoarthritis and Joint Pain

Here’s a meta-analysis of the use of Turmeric and Curcumin for Osteoarthritis and Joint Pain (Daily James W. , Yang Mini , and Park Sunmin. Efficacy of Turmeric Extracts and Curcumin for Alleviating the Symptoms of Joint Arthritis: A Systematic Review and Meta-Analysis of Randomized Clinical Trials. Journal of Medicinal FoodVol. 19, No. 8.). The study

systemically evaluated all RCTs of turmeric extracts and curcumin for treating arthritis symptoms to elucidate the efficacy of curcuma for alleviating the symptoms of arthritis.

The conclusions were

…meta-analysis of four studies showed a decrease of WOMAC with turmeric/curcumin treatment (mean difference: −15.36 [−26.9, −3.77]; P = .009). Furthermore, there was no significant mean difference in PVAS between turmeric/curcumin and pain medicine in meta-analysis of five studies.

…these RCTs provide scientific evidence that supports the efficacy of turmeric extract (about 1000 mg/day of curcumin) in the treatment of arthritis. However, the total number of RCTs included in the analysis, the total sample size, and the methodological quality of the primary studies were not sufficient to draw definitive conclusions. Thus, more rigorous and larger studies are needed to confirm the therapeutic efficacy of turmeric for arthritis.

I haven’t found any other solution to my shoulder pain and I refuse to use NSAIDs or pain medications so I am trying Turmeric Curcumin.


Increasing Fat Oxidation Rates in Exercise

Fat Oxidation rates can be increased through training. This was demonstrated in this study (Hetlelid KJ, Plews DJ, Herold E, Paul B Laursen, Stephen Seiler. Rethinking the role of fat oxidation: substrate utilisation during high-intensity interval training in well-trained and recreationally trained runners.  BMJ Open Sport & Exercise Medicine 2015.). The study compared well trained (WT) to recreationally trained (WT) athletes on the same HIIT test. Both groups had similar carbohydrate oxidation rates but the WT athletes oxidized substantially more fat than the RT athletes.

Fat oxidation (0.64±0.13 vs 0.22±0.16 g/min for WT and RT, respectively) accounted for 33±6% of the total energy expenditure in WT vs 16±6% in RT most likely very large difference in fat oxidation (ES 90% CL=1.74±0.83) runners.

Despite similar RPE, blood lactate and carbohydrate oxidation rates, the better performance by the WT group was explained by their nearly threefold higher rates of fat oxidation at high intensity.

Note that this was not comparing Low Carb to High Carb athletes but it does offer the possibility that increased fat oxidation can lead to an increase in performance.

2018-07-08 Update: Found this interview with one of the study authors (Paul Laursen, PhD, and Dr. Phil Maffetone: Rethinking The Role of Fat Oxidation At High Intensities, Plus Practical Diet and Training Applications To Yield Results and More).

I don’t think this study invalidates anything related to RER and the VO2max testing. The FASTER study curves shows that some athletes (low carb ones in particular) are better at burning fat at higher intensities.

This does reinforce the value of training to increase fat oxidation rates. Increased volume is only possible through longer training which is done at a lower heart rate.


Ketones and Blood Sugar Responses to Exercise


Determine the effects of exercise on blood glucose and ketone levels.

The prediction prior to exercise was that blood glucose levels would increase and ketone levels would decrease immediately following exercise but would rebound to a blood glucose level that was lower than the baseline and ketone levels would increase to a level higher than the baseline within a couple of hours.


The subject of this study is a male, 58-year old, approx 75 kg in weight who has been doing CrossFit training for about 10 months. Subject eats a ketogenic diet (less than 30 grams of carbohydrates per day). Subject was fasted overnight (about 14 hours) and exercise was performed in the morning. Subject had one cup of coffee with salt (Morton Lite Salt plus Sea Salt) added prior to exercise and one cup of same post-exercise. Exercise routine consisted of warmup followed by relatively high intensity workout. The warmup consisted of calisthenics and a 400 M run taking a total of about 8 minutes. The intense portion of the workout took about 16 minutes. Heart rate was recorded using a Samsung Gear Sport heart monitoring watch. Blood sugar was measured using a Livongo Blood Glucose Meter. Ketone Levels were measured using a Keto Mojo Blood Ketone meter.


Blood Ketone levels were 1.0 at the start of the exercise, fell to 0.3 at the end of the exercise, 0.4 at 1 hour post exercise and 1.5 at 2 hours post exercise. Initial ketone level indicates subject was fasted and was in nutritional ketosis. Blood Sugar levels were 92 at the start of the exercise, 129 at the end of the exercise, 82 at 1 hour post exercise and 89 at 2 hours post exercise. Subject’s heart rate reached a maximum of 188 beats per minute and was noted to be at maximum for 15 minutes, vigorous for 7 minutes and moderate for 9 minutes.


Intense exercise results in an increase in Blood Glucose levels which fall to lower than baseline level within in an hour. Intense exercise also results in a decrease in measured ketone levels in the blood. These reactions could cause psychological distress to someone who sees them for the first time in themselves but are common reactions to intense exercise.

The Intense Workout

The intense portion of the workout consisted of Medicine ball Cleans using a 14-pound medicine ball and Strict Chest To Bar pullups using resistance bands. The progression was as follows:

The time to complete the intense portion was:

Data – Chart

Time   Note Blood Sugar Ketone Level
-45 mins Start of exercise 92 1.0
0 mins End of exercise 129 0.3
60 mins Post-exercise 82 0.4
120 mins Post-exercise 89 1.5

Heart Rate Data

Additional Watch Data was:

Fat vs Lean Gains in Athletes

This study looked at the body composition during weight increases and decreases in athletes (Silva AM, Matias CN, Santos DA, Rocha PM, Minderico CS, Thomas D, Heymsfield SB, Sardinha LB. Do Dynamic Fat and Fat-Free Mass Changes follow Theoretical Driven Rules in Athletes? .Med Sci Sports Exerc. 2017 Oct;49(10):2086-2092.). The results were startling:

Athletes that lost BW used 90% of the energy from FM while in those gaining BW, 95% was directed to FFM. When BW is lost, dynamic changes in its composition do not follow established rules and predictions used for lean or overweight/obese nonathletic populations.

Credit to Sigma Nutrition for this subject. Check out their podcasts.

Ran in a 5K Race 2018-05-20

I never imagined two years ago – when I was 285 lbs – that I would ever be able to run in a 5K race. I’ve only been training for a week when I saw there was a local race this weekend so I thought I would enter. I figured I’d probably take around 45 minutes to run the 5K (3.1 miles) – there are some pretty decent hills in my neighborhood. I ended up finishing in 31:38 and took 2nd in my age group.

I wanted to run the 5K to “get it over with” but I’m considering getting back to the training routine Monday morning. I’d like to beat 30:00.

I easily did this fat fueled – without any carbs. Avoided the carbs at the awards ceremony, too. I did eat a few squares of pizza – tossed the crust and ate the toppings only.


Cortisone Injections in Diabetics

I had a cortisone shot in my shoulder for pain yesterday.

Today my blood sugar is up into the mid 130’s. That’s high for me but no where near what it used to be when I had this shot years ago. My blood sugar used to go into the low 200’s then.

I do remember that the effect lasts a few days. The science shows this is the case (The Journal of Hand Surgery. July 2006, Volume 31, Issue 6, Pages 979–981. The Effect of Corticosteroid Injection for Trigger Finger on Blood Glucose Level in Diabetic Patients. Angela A. Wang, MD,

The blood glucose level increased after corticosteroid injection for all patients. The first morning after injection showed the biggest increase in blood glucose level: 73% more than the average preinjection levels. By the fifth morning after injection the blood glucose levels still were increased by 26% more than the preinjection levels. This trend was marked particularly in type I diabetic patients, who had an average blood glucose level increase the first morning after injection of 145%, which decreased over 5 days to 22% greater than baseline levels.

A second study showed a significant mean increase over the next few days after the shot (J Hand Surg Am. 2014 Apr; 39(4): 706–712. Blood glucose levels in diabetic patients following corticosteroid injections into the hand and wrist. Jeffrey G. Stepan,

I wonder if this relates to increased blood sugar secretion or an insulin resistant reaction? This site indicates that they cause temporary insulin resistance (Corticosteroids and Diabetes).

One of the side effects of oral corticosteroids is that they can increase blood glucose levels and increase insulin resistance, which can lead to type 2 diabetes.

Typically, blood glucose levels will return to normal after you finish taking the steroids but in some cases, particularly if you have pre-existing risk factors for type 2 diabetes, you may be diagnosed with this form of diabetes.

CrossFit Competition – Festivus Games

Last month, I competed in my first CrossFit competition, the Festivus Games.

I did not do all that great but it was fun. And hard. Mostly hard. A little fun.

That’s 518th out of 666 entries. The only reason I placed that high is that I made it into the finals. The top five people in every box got into the finals and CrossFit Pittsburgh wasn’t all that crowded.


Exogenous Ketone Experiment Results

I finished off the jar of exogenous ketones that I bought and recorded my own experiences.

Effects on Weight

Here’s my weight on the day taken in the morning before and the morning of the day after I took the PerfectKeto Exogenous Ketones.

Date Wt before Wt after Wt Change Calories
5/10/2018 167.95 169.35 1.4 2219
5/11/2018 169.35 170.5 1.15 2243
5/16/2018 165.69 166.1 0.41 2221
5/17/2018 166.1 167.05 0.95 2153
5/21/2018 162.59 164.71 2.12 2504
5/22/2018 164.71 166.51 1.8 2317
Average 1.31 2276
Std Dev. 0.6 112.7

Why Weight Gain?

In my n=1, there was a consistent weight gain (1.3 +/- 0.6 lbs) the day after I took the exogenous ketone supplement. So if you are already on a ketogenic diet and are expecting exogenous ketones to help you lose weight you could be really surprised and disappointed. I wasn’t disappointed – I did this experiment since my body weight is fairly stable and I am not concerned about gaining a lb or two.

The question is especially pertinent since higher ketone levels are usually indicative of fat burning and weight loss. There’s some belief that exogenous ketones cause your own body to reduce its generation of ketones. I can’t say whether or not I would have lost weight on those days but I can say that there was a strong correlation to weight gain on the days I supplemented with the product.

It wasn’t extra calories consumed on those that caused the weight gain. My average calorie count is right in line with my maintenance calories. At the very least there was nothing in the food consumed that day that would come anywhere near a 1.3 lb weight gain.

Also, there’s only 15 calories in each product serving so there weren’t enough calories in the supplement itself to cause such a consistent and significant day-to-day weight gain.

The ingredients list might be a clue. Magnesium, Potassium, Cocoa, Stevia leaf, Vitamin C.

They don’t list Sodium as an ingredient although some exogenous ketones include Sodium. If there was Sodium then that could be the reason for the temporary weight gain. But the binding salt could be the Magnesium or Potassium. There’s no reason to think that Potassium alone should cause temporary weight gain. I wonder if there is Sodium? That could provide the most plausible explanation for the temporary weight increase. The Perfect Keto site states:

Ketone salts are formed when the ketones are bound to a salt, typically sodium or calcium, potassium, or magnesium, to improve absorption rate.

This site (BHB Salts) states:

The “BHB salt” is simply a compound that consists of sodium (Na+), potassium (K+), and the ketone body β-hydroxybutyrate.

The weight gains were temporary and quickly reversed in the days after I discontinued the product.

Rat studies showed rats gained less weight than controls when were fed ketone supplements (Shannon L. Kesl, Angela M. Poff, Nathan P. Ward, Tina N. Fiorelli, Csilla Ari, Ashley J. Van Putten, Jacob W. Sherwood, Patrick Arnold, and Dominic P. D’Agostino. Effects of exogenous ketone supplementation on blood ketone, glucose, triglyceride, and lipoprotein levels in Sprague–Dawley rats. Nutr Metab (Lond). 2016; 13: 9.).


The Keto Base Chocolate Sea Salt product costs $59 for 15 servings. That’s pretty expensive. That’s about $4 a serving which seems like a lot compared to my other supplement costs.

Mood Changes?

I think I saw a very small mood improvement but I really can’t quantify this. It may have had more to do with having more water from salt?

I did notice I developed a tiny bit of an addiction to the product. Perhaps it was just the chocolate salt mix taste that I was looking forward to. It wasn’t hard to stop so the addiction wasn’t that strong and the $4 a serving made it easier (that’s about the amount of money I spend each day on food anyway).

Performance Increases?

I didn’t perform any particular exercise benchmarks to determine if I had any performance increases. I also took the supplement early in the morning in my first coffee so I wasn’t exercising around the time. I also don’t know if it would have any time effect with respect to exercise.

Advantages of Exogenous Ketones?

I can imagine a potential use of exogenous ketones in people who are just transitioning into the ketogenic diet. It could allow them to make the transition easier and may ease the keto flu. It would be interesting to see if it has any better effects than electrolyte supplementation – which is a lot cheaper.

However, this is an application that I can imagine few taking due to the cost. People “try” diets and starting this diet with a $60 product might be too much for most people to swallow (pun intended).