28 Day CGM Experience

Rahul Patil, functional medicine coach and supporter of The Noakes Foundation, and Prof Noakes, recounts his personal experience using a Continuous Glucose Monitor (CGM) to track and monitor his fluctuating glucose levels over a 4 week period. Due to the rising concerns of diabetes and obesity in India Rahul sought to bring awareness to the growing incidence of metabolic diseases within the country and the common, carb-loaded diet consumed daily by Indians. He kindly shared his journey with us.

28 Day CGM Experience

My interest in Diabetes grew the moment I realised I was Insulin Resistant and had been silently suffering the consequences of Insulin Toxicity for years. India has been a hub of Metabolic Diseases for many years. I thought of creating awareness about how our food choices can either make us sick or lead us to health. I found my calling in educating people about “Why food is the only medicine we need” and “How food works as information to our cells”. In other words genetics loads the gun, while lifestyle and the food we eat pulls the trigger.

Standard Indian Diet
Just like the Standard American Diet (S.A.D), we, as Indians, have a very peculiar way of eating and I call it S.I.D, Standard Indian Diet. A while back I did a Survey on S.I.D and found out what I have always feared – Indians eat 90-100% food in different forms of Carbohydrates and readily add to it the easily available fast food based on S.A.D, Burgers, Pizzas, Chips etc. This survey only confirmed my doubts and turned it into a goal to create awareness about optimal human food. Thanks to role models like Dr Noakes, it has been a fabulous journey of self discovery and learning. My 28 Day Continuous Glucose Monitor Experiment was intended to show the physiological effect of S.I.D and how it is creating a silent pandemic of metabolic diseases, not just in India but the world over. I used an Abbott Freestyle Libre Pro for the CGM data, a Dr Trust Instant Glucose Monitor for the 1st week and later changed it to Accuchek Instant Glucose Meter as I found errors in Dr Trust Instant Glucose Monitor readings. I used a Abbotts Freestyle Libre Neo blood ketone Meter to monitor blood ketones and I weighed myself regularly during the course of my experience.

I divided 28 Days in 4 different phases as follows:

  • 1st Week – One Meal a Day – Fat & Protein
  • 2nd Week – Three Meals a Day – Fat & Protein
  • 3rd Week – 7 Day Water Fast
  • 4th Week (Part 1) – 4 Days S.I.D Standard Indian Diet with 3 Carb rich meals, including Fat & Protein
  • 4th Week (Part 2) – 3 Days of Water Fast (with occasional Black Coffee), intended to see how long it takes to get back into nutritional ketosis

Week 1

The result of my first week was as expected considering I was eating 1 meal a day. The meal composition was fat and protein and I expected to be in nutritional ketosis throughout the first week.

Blood ketones recorded in the first week – 20thSept20 – 2.9 mmol/L, 22ndSept20 – 1.0 mmol/L, 24th Sept20 – 2.2 mmol/L.

I started my CGM experiment on 18th September 2020. The reading on the left is taken on 20th Sept 2020. The first half of the 1st week I relied on Dr Trust for my instant blood glucose readings which were quite erratic and did not correlate with the CGM data and blood ketones data. I switched to Instant Accuchek Performa Meter from 23rd Sept 2020, and posted some comparative readings of both instant blood glucose meters. In the image to the left, you can see why I had my doubts regarding the blood glucose reading shown by Dr Trust Bg Meter. Below is a excerpt from FreeStyleLibre.us explaining the difference between a CGM & BG Reading.

*Are glucose readings different between CGM and BGM?

Instead of taking glucose readings from your blood, CGM sensor glucose readings are taken from the interstitial fluid (ISF), a thin layer of fluid that surrounds the cells of the tissues below your skin. Blood glucose readings tend to be about 5 to 10 minutes ahead of interstitial glucose readings. For most treatment decisions, sensor readings from the FreeStyle Libre 14 day system can replace fingerstick readings.*

The difference between Dr Trust and Accuchek Blood Glucose Monitor readings were quite vast and Accuchek readings correlate with the CGM data and the blood ketone data.

On the 24th Sept, the last day of my 1st week with OMAD, my blood ketones were 2.2 mmol/L and blood glucose on Accuchek was 107 mg/dL, this was the only time when Dr Trust BG readings matched Accuchek BG readings.

Conclusion at the end of OMAD/1st week CGM

Experiment – One meal a day of Fat & Protein comfortably
keeps one in nutritional ketosis.



Week 2 Three Meals a Day (TMAD)

The third week threw some surprising results and numbers. I was still on a fat and protein diet but 3 meals a day for 7 days. The ketones levels remained well within nutritional ketosis range even after eating 3 meals a day. In fact the blood ketones were slightly beyond the nutritional ketosis range.

You can see in the image on the right my blood ketones levels were 3.8 on 28th Sept 2020. Blood glucose was 88 on Accuchek and Dr Trust Meter was showing consistently higher readings which proved it was not accurate.

Conclusion for the second week

Nutritional ketosis can be well maintained even on a 3 meal a day plan provided one is on a fat and protein diet (almost carnivore).  I was not counting calories or portion size, I was eating until I was satisfied/satiated.

Before starting a 7 day water fast which I did during my 3rd week I had a feast on the previous night, which was my third meal of the day. This meal consisted of red meat and 4 organic eggs made in cheddar cheese. This feast resulted in a drop in my blood ketone levels from 2.1 to 0.3, well out of nutritional ketosis.



Conclusion at the end of 3MAD/2nd week

Too much of a good thing, even if that is fat and protein, can easily put one out of nutritional ketosis. However, if I ate to satiation, even if it was 3 meals a day, it can easily keep one in nutritional ketosis.

Day 1 of 7 day water fast

My blood glucose readings  were not a surprise considering the feast I had the  previous night in anticipation of zero food for the next 7 days. My blood glucose was 111 mg/dl and blood ketones were 0.2 mmol/L, Weight was 75.5 Kg.

Between 2nd Oct and 8th Oct, which was my Water  fast week, the blood ketones consistently went up and at the same time blood glucose went down. One can clearly see the inverse relationship between blood glucose and blood ketones in the graph on the left. Post-fat and protein feast: it nearly took 36 hours to get back into nutritional ketosis.

On Day 2 of the Water Fast, my blood ketones increased to 1.2 mmol/ L compared to Day 1 blood ketones 0.2 mmol/L. It may have taken slightly fewer than 36 hours to reach nutritional ketosis after a fat & protein feast. 

At the end of the 7 day water fast my blood ketone levels were 6.3 mmol/L and my blood ketones just before breaking my fast were 6.5  mmol/L.

On the left here you can see my readings just before I broke my 7 day water fast with a bowl of ghee.

My body weight dropped to 74.4 kg in 7 days, which was a 1.1 kg weight loss. On the CGM my average glucose was 49 mg/dl while on the Accuchek my blood glucose was 71 mg/dL.

I broke my 7 day water fast with saturated fat, which is a bowl of cow ghee. This was followed up with a Standard India Diet Meal which comprises of carbohydrates.

My last and 4th week of the CGM Experiment consisted of following a Standard Indian Diet (which comprises of carbohydrates) for 4 days and a 3 day metabolic reset fast to get back in nutritional ketosis.

Standard Indian Meals

First 4 Days of 4th Week

These are my readings the next day after I broke my fast with a Standard Indian Diet rich in carbohydrates. One can clearly see the drop in my blood ketone levels from a peak of 6.5 mmol/L to 4.4 mmol/L and the rise in blood glucose from 71 to 94 mg/dL. For the next 4 days on S.I.D my blood ketones consistently dropped and blood glucose went up.

In this graph below one can clearly see the rise in blood glucose and the drop in blood ketones on a Standard Indian Diet rich in carbohydrates. The inverse relationship is again seen here between blood glucose and blood ketones.

On the last day of my S.I.D Diet my blood ketones were their lowest at 0.2 mmol/L and my blood glucose had reached its peak at 150 mg/dL post meal. Body weight had increased by 1.2 Kg in just a matter of 4 Days. Average glucose on CGM had increased from 56 to 64 mg/dL.

Conclusion of the 4 Day S.I.D diet – A nutritional ketosis state is easily reversed after eating a carbohydrate rich diet. It took nearly 36 – 48 hours to get out of nutritional ketosis. My blood ketone levels dropped from 6.5 mmol/L on 8th Oct evening to 0.3 mmol/L on 10th Oct evening.

Metabolic Reset

After eating a S.I.D diet rich in carbohydrates it was important to understand how long it takes to return to nutritional ketosis. Earlier we have seen a average time of 36 hours either to get into ketosis or get out of ketosis. But that was with a fat and protein meal and in fasted state. So the last 3 days of the 28 day CGM Experiment is to check how long does it take to get back into nutritional ketosis, I call it the Metabolic Reset.

I believe once one understands the average time it takes to get into nutritional ketosis from either a carbohydrate rich diet or over eating fat & proteins, it will help and be a important part of designing nutrition plans for athletes, general population and recovering patients under medical supervision.

My observations for the next 3 days of Water Fast meant to get back into nutritional ketosis.

Day 1 Metabolic Reset – blood glucose readings were 101 mg/dL on Accuchek & average 65 mg/dL on CGM, while my blood ketones were 0.2 mmol/L.

It took nearly 36 hours on a water fast post a carbohydrate rich S.I.D diet to reach back into nutritional ketosis.

At the end of 3 Day Metabolic Reset Water Fast my readings were as follows.

Blood ketones went up to 2.2 mmol/L from 0.2 mmol/L. Blood glucose on Accuchek went down to 88 mg/dL from the peak of 150 mg/dL, which was post an S.I.D meal. My CGM average stayed the same in the span of  days at 64 mg/dL.

Conclusion of 3 Day Metabolic Reset Fast after a carbohydrate rich S.I.D diet

It takes an average of 36 to 48 hours to get back into nutritional ketosis. A Metabolic Reset Fast is a great way to get back into nutritional ketosis



Here on the left in the graph one can see the change in blood glucose and blood ketones during a Metabolic Reset Fast. In 3 days Water Fast blood ketones went up to 2.2 mmo//L from 0.2 mmol/L.








Conclusion for the 28 Day CGM Experiment 

This experiment started as a way to understand the response of blood glucose and blood ketones in various conditions like One Meal a Day (OMAD), 3 Meals a Day (3MAD), Water Fast and the Influence of a Carbohydrate Rich Indian diet on getting into nutritional ketosis, maintaining nutritional ketosis and getting out of nutritional ketosis.

These 4 weeks were divided into 4 phases and each phase provided its own conclusions.

Overall it helps us to understand that eating a fat & protein diet helps in maintaining nutritional ketosis, whether one is eating OMAD OR 3MAD. On the other hand over eating on fat & protein can also put oneself out of nutritional ketosis just the way a carbohydrate rich S.I.D diet can. It takes an average time of 36 to 48 hours for someone to get back into nutritional ketosis after an indulgence in carbohydrate rich diet or over eating of fat & protein.

A Metabolic Reset method of going on a water fast for 36 to 48 hours can easily get someone back into a nutritional ketosis state. Whether it is a Standard Indian Diet or a Standard American Diet, a diet rich in carbohydrates will raise your blood glucose, reduce your blood ketones, get you out of nutritional ketosis, stop your body from metabolising fatty acids and will make one gain weight. I gained about 1.2 kgs in just about 4 days of a Standard India Diet.

About the Author

Rahul Patil, an advocate for health and fitness, began his journey as a fitness instructor. He had a passion for helping others achieve their fitness goals. In his pursuit for knowledge Rahul Patil decided he wanted to invest in his education and received a Functional Medicine degree from FMU University in 2018. Today Rahul helps countless people in India and internationally reverse diabetes, reverse obesity and helps athletes improve their metabolic health by performing basic assessments to understand insulin sensitivity.







Disclaimer: The views and opinions represented in this blog are personal to the author, and do not necessarily represent the position of the Foundation. The Foundation has not reviewed or endorsed the apparatus referred to in the article. The content of this article should not be considered as medical advice, it is for informative and educational purposes only.

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