I did a 5-day water fast with daily blood glucose and ketones measurements

I have been on Intermittent Fasting (IF) for over a year and I gradually increased my IF from 16/8 to 18/6, 20/4 and sometimes reaching 24 or 25 hours without food. There are so many resources on the web on the benefits of IF such as reversing insulin resistance, weight loss (because one tends to eat lesser with IF and creates a sustainable calorie deficit) and many more.

However, to get some of the better benefits such as fat burn (ketosis) and autophagy, a fast that is beyond 24 hours is required. This is because you may already spend 24-48 hours depleting your glycogen store in your liver and muscle before you can enter ketosis. This is the time that autophagy can also begin. While on a keto diet or IF, one tends to drink black tea / coffee but that is thought to interrupt the autophagy process by stimulating insulin response. As such, I planned to be extremely strict on my 5-day water fast – nothing except plain water.

I started on Sunday, 28 November 2021 at 6:30pm – that is the time I swallowed my last bite of dinner. I at like there was no tomorrow. As a result, I weighed in at 90.45KG that night. Although I started on Sunday 6:30pm and is to break my fast at the same time on the following Friday, let’s take Monday as Day 1 for simplicity.

I bought a tube of ketone urine test strips in advance but I gave it some thought and felt that I should invest in a more precise data collection since I’ll be committing so much to this 5-day fast. It would be a waste if I had to fall back on test strip indicators that are subjective. I will then use Glucose-Ketones-Index (GKI) to see how am I doing in terms of ketosis.

What is GKI (Glucose Ketones Index)

Day 1

I went out to grab blood glucose and ketones strips for my Abbott Freestyle Optium Neo Blood Glucose & Ketones Monitoring System

  • Mood: Totally fine – this is within my usual IF practice anyway
  • Energy level: Great
  • Mental clarity: good
  • Blood Glucose: 4.8 mmol/L
  • Blood Ketones: 0.3 mmol/L
  • GKI: 16 (Not in ketosis)
  • Weight: 88.75 kg
  • Remarks: My body has yet to fully use up the glycogen store due to my high carb meal the day before. I expect this to be depleted within the next 12-24 hours.

Day 2

  • Mood: A little grumpy
  • Energy level: A little lesser than normal
  • Mental clarity: good
  • Blood Glucose: 3.6 mmol/L
  • Blood Ketones: 2.1 mmol/L
  • GKI: 1.7 (Therapeutic ketosis)
  • Weight: 88.25 kg
  • Remarks: I jumped straight into ketosis. The hunger was okay but my mind is

Day 3

  • Mood: neutral
  • Energy level: it’s alright
  • Mental clarity: good
  • Blood Glucose: 3.2 mmol/L
  • Blood Ketones: 3.6 mmol/L
  • GKI: 0.9  (Highest therapeutic ketosis)
  • Weight: 87.2 kg
  • Remarks: Technically hypoglycaemic if based purely on blood glucose level. However, I am burning fats and ketones so this level of glucose is still safe. The body is using protein to produce the little bit of glucose needed by certain parts of the body that cannot burn fat/ketones.

Day 4

  • Mood: grumpy
  • Energy level: lower than usual
  • Mental clarity: great
  • Blood Glucose: 3.3 mmol/L
  • Blood Ketones: 4.7 mmol/L
  • GKI: 0.7  (Highest therapeutic ketosis)
  • Weight: 86.75 kg
  • Remarks: I can’t take my mind of food. Every time I open FB/IG, someone is posting about food they bought / eating or how-to style videos about preparing food. I went into Grab app and attempted to schedule some deliveries for the next day ….

Day 5

  • Mood: surreal
  • Energy level: lower than usual
  • Mental clarity: great
  • Blood Glucose: 3.1 mmol/L
  • Blood Ketones: 6.2 mmol/L
  • GKI: 0.5  (Highest therapeutic ketosis)
  • Weight: 85.4 kg
  • Remarks: I walked for about 2.4km to run errands (Grab groceries and such for my breaking of fast). Because of that exertion, I hit an all time high of 6.2 mmol/L of ketones and 3.1 mmol/L of glucose.

Data Collected

May be an image of text that says "Howard's Ketones, Glucose & GKI Ketones (mmol/L) 8 16 Glucose (mmol/L) GKI 6 4.8 20 3.6 6.2 4.7 3.6 3.2 15 2 2.1 3.3 0.3 1.7 3.1 10 0 29/11/2021 0.9 30/11/2021 0.7 5 01/12/2021 0.5 02/12/2021 Date 0 03/12/2021"

May be an image of text that says "Howard's weight, body fat and muscle mass Weight (KG) 100 90.45 88.85 Body Fat (KG) 88.75 80 Muscle Mass (KG) 88.25 87.5 87.2 60 86.75 58.20 86.05 85.4 58. FI 57.90 40 28:76 57.90 PM 57.70 58.20 27.45 26.89 20 28/11 pm 26.92 26.43 26.16 29/11 pm 25.94 1/12 am 24.70 24.77 2/12 am 3/12pm pm"

My final blood glucose and ketones blood test on Day 5


As you can see, despite not eating for 5 days, my blood glucose level did not drop below 3 (which would have been dangerous). This is no coincidence as the body just produces enough glucose to keep some parts of my body functioning while the bulk of my body ran on fats and ketones. Will I do it again? Yes – twice a year. There is no need to go on a 5-day fast that often. However, I am contemplating going on a weekly 48-hour fast on top of my IF.

A word of warning: if you are diabetic, please consult a doctor first because instead of ketosis, you can slip into ketoacidosis which is potentially life threatening!


Why I took Moderna for my booster after 2 Pfizer shots

Disclaimer: This should not be taken as medical advice as I am just sharing my experience as someone who had taken 2 Pfizer shots and decided to take Moderna as my booster.

I had my first and second vaccinations back in March and April 2021 and that made me eligible for my booster yesterday (19 October). I made the conscious effort to “mix” vaccines by going for Moderna even if it meant that I had to travel slightly further to a vaccination centre that carries Moderna when there’s already a Pfizer vaccination centre within a 5-minute walk from my home. I am also aware of the generally worse side effects based on anecdotal accounts from Moderna recipients.

So why did I still choose to bring this upon myself?

First of all, I have no doubt that Pfizer and Moderna are both great mRNA vaccines. They both greatly reduce the chances that one will get hospitalised due to severe symptoms from Covid-19. However, in the recent months, there has been early reports that Moderna is more effective than Pfizer against the Delta variant.

In a study of more than 50,000 patients in the Mayo Clinic Health System, researchers found that the effectiveness of Moderna’s vaccine against infection had dropped to 76 per cent last month – when the Delta variant was predominant – from 86 per cent early this year.

Over the same period, the effectiveness of the Pfizer-BioNTech vaccine had fallen to 42 per cent from 76 per cent, researchers said.

Source: https://www.straitstimes.com/world/united-states/moderna-may-be-superior-to-pfizer-against-delta

Historically, there were findings of vaccine mixing (heterologous prime-boost) could be more immunogenic than single vaccines (homologous prime-boost). While such a study has yet to be conducted on a Pfizer-Moderna combination, authorities around the world have begun allowing mixing of vaccines to ease the burden on logistics and supplies.

In Singapore, our authorities view mRNA vaccines as “similar” and have therefore officially allowed the mix as of 17 September 2021.

Source: https://sg.news.yahoo.com/covid-booster-pfizer-biontech-moderna-vaccine-134827443.html

Side effects of mixing Pfizer and Moderna Vaccines

Before going for the booster shot, I tried searching for side effects of mixing the two vaccines but without success. So here’s my account of the 36 hours post vaccination:

19 October 2021

9:30am: I arrived at the vaccination site ahead of my 10am appointment. I was made to acknowledge that I am switching from Pfizer to Moderna – twice. Once at the registration counter and then at the vaccination booth.

9:36am: Vaccination done. Time for the 30-minute on-site observation.

10:06am: Called to the discharge counter to check if I’m okay. All good. I then took a 4km casual walk home (strenuous exercise is not allowed so I made sure that it was a casual stroll).

I technically had the day off from work (vaccination benefit) so I chilled for the most part of the afternoon.

4pm: Short nap – no fever yet.

6pm: Felt a bit lethargic. No fever yet. Unable to get up to send my daughter for her piano class.

7pm: Got up for dinner. No fever yet. Realised that there’s some work to be done.

8pm: Slight fever at 37.9 C.

10pm: Fever at 38.5 C.

11pm: Fever at 39 C, chills kicking in. This continued through the night.

20 October 2021

7am: A lot of pressure on my entire face – like it’s going to explode. I could barely wake my kids up for school. Temp: 38.9 C.

3pm: I only got up at 3pm and temperature was 38.1 C. Attended a few meetings and left home to get my medical leave to cover my absence for the good part of the work day.

7pm: Temperature at 37.6 C (Might be the paracetamol that I finally took)

10pm: Temperature 38.4 C + chills. Here we go again.

I’ll update this post until I’ve stopped experiencing any effects of the vaccination.

Conclusion about mixing Pfizer / Moderna for booster shot

It has always been anecdotally known that Moderna recipients suffer longer  fevers, headaches and chills compared to Pfizer recipients. This is why I am not at all surprised if my symptoms is going to go on for another day or two. This is within my expectation and I made that informed choice.

Should you mix vaccines? My personal opinion is yes. Mixing vaccines could potentially offer a wider spectrum of coverage. Even if it does not offer significant benefits, there should not be any ill effects of mixing the vaccines otherwise this practice would have been banned around the world. At the end of the day, this is your personal choice. Mixing or not, just get your 2 +1 vaccinations done!


5-HTP – my personal recommendation for moodiness, anxiety, depression and general sleep difficulties

5-HTPIf you feel moody, anxious, depressed, stressed or have any combination of these, I would like to personally recommend you to take 5-HTP supplements.

5-HTP is an amino acid that is integral in the production of serotonin, a neurotransmitter that causes happiness and positivity. Serotonin is produced by the body from tryptophan and 5-HTP is the immediate precursor to serotonin.

5-HTP is a precursor to serotonin and has been studied extensively for its role as a treatment in depression and weight loss. It also has an important role in sleep regulation, appetite control, immune function and cardiovascular health.

Truth be told, I don’t take this every single day. I use it specifically when I have had late nights and felt that I really need to sleep well tonight. Quite consistently, I get restful sleeps without my mind going wild about things I have to do the following day or reflecting on things that have happened. The supplements are not expensive and are pretty safe to consume.

You can get the same brand that I’m taking (Now Foods, 5-HTP, 100 mg) or get it from your own preferred supplement company.