Want to lose fat? DON’T aim for stable blood sugars! (Why your CGM could be making you fat)
If there was anything I thought I knew when I was an insulin-fearing keto zealot, it was:
- the blood sugar roller coaster is bad, and
- stable blood sugars were good.
According to the keto gurus that I was following, if you wanted to lose fat and optimise your metabolic health, the most important thing you could do was to eat fewer carbs to achieve flatline blood sugars to “turn off insulin”.
Even today, with the keto movement in decline, there is still plenty of confusion about the role of stable blood sugars and insulin levels and in weight loss. Many people assume that stable blood sugars will lead to lower insulin levels which will automatically lead to weight loss.
Since we started the Data-Driven Fasting Facebook Group, I have had a barrage of questions as people try to make sense of their blood sugars.
Now, more than six hundred people have completed the baselining phase in their Data-Driven Fasting Spreadsheet.
Now the the data is in.
It seems eating a high-fat diet to stabilise your blood sugar is unlikely to help you lose weight.
Rather than worrying about your blood glucose after meals, your blood glucose before meals is a more powerful way to optimise your metabolic health.
By managing your blood sugars before you eat (through meal timing and optimised food choices), you can optimise the numbers that matter when it comes to managing your metabolic health (i.e. BMI, waist to height ratio and waking blood sugars).
Eighteen years ago, I married Monica, who has Type 1 Diabetes.
We started to think about having kids. She knew she needed to get her blood sugars under control to minimise the long list of dire complications of pregnancy with high blood sugars.
She has lived with Type 1 Diabetes since she was ten years of age. But sadly, no endocrinologist or diabetes educator had ever been able to tell her what to eat or how to manage her insulin dosing to help her gain control of her diabetes.
The conversation always went along the lines of…
Endo: “Your blood sugars and HbA1c are high. You should try to get that down.”
Monica: “How doc? What do I do? What do I eat? What do I change?”
Endo: “It just needs to be better. Here’s your script for insulin and drugs. See you in six months.”
Luckily, when we were looking at having kids, we found a progressive family doctor who was able to teach us enough to enable Monica to get reasonable control for our two pregnancies. They seem to have turned out OK.
Bernstein was an engineer who later became a doctor after he got frustrated at people not listening to his theories about diabetes management that he discovered after analysing his own blood sugars. He’s now 85 and going strong. He continues to walk the talk.
Recently, we had to see an endocrinologist and a diabetes educator get a new insulin pump for Monica so we could set up a closed-loop CGM/insulin delivery system.. The conversation with both of them went along the lines of
“Wow. What a fantastic HbA1c! I don’t think I can teach you anything! You know what you’re doing… But wait. Your chart says you haven’t seen an endocrinologist for seven years.”
I have learned a lot after diving deep into the Type 1 Diabetes headspace.
I also learned that context is critical. Especially if you are part of the 99.99% of the population who has a functioning pancreas.
Before I get into the data analysis and learnings from people using Data-Driven Fasting, let me give some background to help you understand the difference between people with Type 1 Diabetes and the rest of us.
What we know from people with Type 1 diabetes
Injecting large doses of insulin to treat elevated blood sugars from modern processed food leaves them on a blood sugar rollercoaster. When their blood sugars are high, they inject more insulin to bring them down.
A few hours later, when they find they have overshot their blood sugar target, they are ravenously hungry and will eat anything and everything until they can raise their blood sugars again. A day in the life of most people living with Type 1 Diabetes looks like this.
Injected insulin is driving their appetite.
If their insulin doses are not precisely matched with the food they eat (which is nearly impossible with synthetic injected insulin combined with synthetic, processed food), they end up overeating because of the insulin they are injecting.
Living with rollercoaster blood sugars sux.
Your appetite, mood or energy levels are in the toilet!
How insulin really works
However, while we usually think of insulin as the hormone that jams energy into our cells, it’s not the full story.
While this is a compelling metaphor, suggesting that we will grow fatter just by eating carbs, irrespective of energy balance, it is fundamentally misguided and incorrect.
We all have approximately 5 grams of glucose (or 20 calories worth) buzzing around in our body at any one time (i.e. about a teaspoon’s worth). It doesn’t take long to use this up once we turn off the flow of energy into our bloodstream.
If you could turn off the release of energy from your liver completely, you would run out of glucose completely in about 15 minutes.
Insulin is the hormone, secreted by the pancreas, that turns off the flow of energy into your bloodstream (from your liver and adipose tissue) until you burn up the energy in your blood from that last meal.
But rather than thinking of insulin as an anabolic hormone that helps things to grow, it’s much more useful to think of insulin as anti-catabolic (i.e. stops us from breaking down and disintegrating).
As per Dr Bernstein’s Law of Small Numbers, once people with Type 1 Diabetes reduce the inputs that require larger doses of insulin (i.e. processed carbohydrates), they can stabilise their blood sugars and insulin requirements.
Smaller inputs of carbs and insulin with meals lead to smaller errors that are easier to correct throughout the day.
Then, because they are no longer injecting excessive amounts of insulin to treat the blood sugar roller coaster, their appetite stabilises, and they tend to achieve healthy body fat levels.
Rather than rollercoaster blood sugars with poor appetite control (which drives an energy surplus), they can have stable blood sugars and healthy appetite signals.
If you are part of the 1 in 8000 people with T1D whose pancreas doesn’t work, stabilising your blood sugars and insulin should be your #1 priority!
The difference between people with Type 1 Diabetes and everyone else!
But, if you are part of the 99.99% of the population that is fortunate enough to have a functioning pancreas, EVERYTHING IS DIFFERENT.
You cannot turn off your insulin pump or stop taking insulin.
No matter what we believe, it just doesn’t work like that!
Your pancreas will always produce just enough insulin (no more, no less) to hold your body fat in storage until you have used up the extra energy from the food that is coming in from your mouth.
When you stop eating, insulin levels lower and your stored energy is allowed to be released for use.
If you have Type 2 Diabetes and eat a heavily processed diet of carbs and fat (e.g. modern processed junk food) your blood sugars will shoot up after you eat and take a long time to reduce back to baseline.
But what if I’m insulin resistant?
Many people have developed a victim mentality (I was one of them).
They blame their obesity on their insulin resistance.
They think being insulin resistant makes it harder for them to lose weight.
But, the reverse is actually true.
When you are lean and insulin sensitive, your body is only too willing to store energy and grow. However, once you become insulin resistant, your body is only too willing to offload the excess energy as soon as you stop jamming in excess energy from low satiety nutrient-poor processed foods.
The chart below shows the difference between diabetic and healthy blood sugar levels (i.e. higher and with larger swings).
Foods that are a combination of fat+carb together enable your body to fill both fuel tanks at the same time. Because your fat stores are already full, the extra energy is not easily absorbed by your liver and body fat, so it overflows into your bloodstream.
You can’t blame getting fat on the insulin.
It’s the foods with carbs and the fat (with low protein) that caused you to overeat. Now you have lots of body fat that requires lots of insulin to hold in storage so long as you keep eating that food.
As you will see below, it’s not that stable blood sugars or a low carb diet is a bad thing. However, eating a high-fat diet to achieve stable blood sugars is nothing more than symptom management. Switching carbs for refined fat and avoiding protein definitely won’t make you lean and metabolically healthy, and may make things worse!
Is insulin REALLY the problem?
Over the past few years, people in the fasting/low carb/keto community have been told by doctors and nutrition gurus that insulin toxicity is the root cause of the majority of our western diseases. Insulin is public enemy number one and reversing “insulin toxicity” is key to weight loss.
We don’t have a lot of data about our insulin response to the food we eat. But data we do have only measures the short term insulin response to foods over the first two hours (as shown in the chart below).
The limitations of this data lead many people to think that high-fat foods have a negligible impact on insulin and hence they are effectively a “free food”.
While glucose will raise your insulin levels quickly, foods that contain fat and carbs together (like milk, shown by the aqua line) will have a smaller initial impact, but insulin will stay elevated after two hours.
While we don’t know that much about the long term insulin effect of high-fat foods, it appears that they will keep our insulin levels elevated for longer. Because fat is stored more efficiently, you don’t actually need as much insulin to hold it in storage on your bum and belly.
Once we understand that insulin simply holds our stored energy back while we use up the energy coming in from our diet, we realise that ALL food will increase insulin over the long term. The problem is not insulin toxicity, but rather energy toxicity (that leads to increased insulin levels).
If we want to lose fat from our body, then it’s not merely a matter of eating fewer carbs and more fat.
Show me the science!
Since launching the Data-Driven Fasting Group, I have been bombarded with questions about blood sugars and insulin as people test their blood sugars and try to make sense of the data they see.
Why do my blood sugars rise when I don’t eat?
My blood sugars are flatline? Why am I still fat?
So many questions!!!
At the time of writing, I now have 625 spreadsheets sitting on my OneDrive folder being continually updated as people check their blood sugars before they eat.
I thought it would be interesting to see what we could learn from this massive dataset.
The most important markers to manage
When it comes to metabolic health and longevity, there are three things we can easily measure that we have embedded in our Data-Driven Fasting Tracking Spreadsheet:
- body mass index (BMI),
- waist to height ratio, and
- waking glucose.
As shown in the charts below, lower is not always better. However, due to the constraint availability of hyperpalatable nutrient-poor processed foods, most of us are well on the higher side of optimal.
Flatline CGM envy… Why are still chasing the wrong numbers?
Many people believe that maintaining stable blood glucose levels is the highest priority and will lead to weight loss.
I’m seeing more and more people (who don’t have Type 1 Diabetes) walking around with (expensive and painful) continuous glucose monitors eating more fat and less protein and less carbs to make sure they maintain flat line blood sugars.
They post their flat line blood sugars on Facebook and Instagram.
A few years ago it was ketone envy. Now it’s flatline CGM envy.
At the time of writing this, I’m in the process of setting up a closed-loop insulin pump system for Monica. The closed-loop combines a continuous glucose monitor with the pump to send continual updates to the basal insulin to bring blood glucose levels back into control like a fully functioning pancreas. A closed-loop CGM is a godsend for people with T1D. But it’s unnecessary and even counterproductive for the 99.99% of the population who have a functioning pancreas.
How much should my blood sugars rise after a meal?
The table below shows the generally accepted limits for blood glucose after meals.
- If your blood sugars after meals are elevated above 140 mg/dL or 7.8 mmol/L then you have prediabetes or diabetes and definitely need to work to reduce our post-meal blood glucose by reducing refined carbohydrates and/or medications to reduce blood sugars (e.g. insulin or metformin).
- A rise in glucose from 100 mg/dL to 140 mg/dL would be accepted as normal and healthy. If your blood sugars rise by less than 40 mg/dL or 2.6 mmol/L after meals then you have a fully functioning pancreas and you would benefit by focusing on your blood sugars before you eat if you have more weight to lose.
In the Nutritional Optimisation Masterclass and Data-Driven Fasting we set tighter limits than this. We recommend that people look to reduce the processed carbs in their diet if their blood sugars rise by more than 1.6 mmol/L or 30 mg/dL.
I was surprised to see that the average blood sugar rise of the logging in the people following Data-Driven Fasting is only about 10 mg/dL or 0.5 mg/dL (not much at all)! It seems people who are fans of fasting (and typically following a low carb or keto diet) already have extremely stable blood sugars!
Stable glucose does not equal fat loss!
As shown in the charts below, people who have a higher waist:height ratio and BMI only have a slightly larger increase in blood sugar after they eat.
The correlation is extremely low (i.e. there is no relationship).
The correlation between the amount your glucose rises after you eat and your waking glucose (another key marker of metabolic health) is also non-existent.
It seems, while normal, healthy, stable blood sugars are a good thing, flat line is definitely not better!
Although stable and lower blood glucose levels are a positive marker of good metabolic health, merely treating the symptom (i.e. elevated blood sugar) rather addressing the cause (i.e. insulin resistance, energy toxicity and excess body fat) doesn’t help.
Unfortunately, many people who believe that fat is a free food because it does not raise insulin levels end up overeating refined fat to maintain stable blood sugar levels. Before long, this leads to fat gain and worsening insulin resistance.
Sadly, there are plenty of keto gurus and their die-hard believers who continue to gain weight because they are trying to optimise the wrong numbers!
There are also plenty of people who get excited about tracking ketone values. BHB ketones in the blood are simply a marker that you don’t have adequate oxaloacetate from protein and/or carbs to enable fat to be burned in the Krebs cycle.
While we often see elevated ketones in the early stages of fat loss, loading up on MCT oil, butter and exogenous ketones will not help you lose weight. Your high ketones may just be a sign that you are driving energy toxicity through your efforts to manage the wrong numbers, with more excess energy backing up in your system.
When we look at glucose variability (i.e. standard deviation/average glucose), we see that there is also a negligible correlation between stable blood sugars and a better waist:height ratio, BMI or waking blood sugars.
Many people have combined fasting with a high fat keto diet in an attempt to achieve stable blood sugars in the hope of weight loss. But sadly, in spite of their Herculean feats of self-deprivation, they just continue to gain weight due to a low satiety nutrient-poor diet that leaves them craving and eating more when the fast is over.
Actively avoiding insulin and any normal rise in blood sugar levels using a high-fat diet tends to lead to poorer satiety, greater energy intake and obesity.
In time, these people often end up with higher insulin levels across the day because they are carrying more body fat which requires more insulin to hold in storage.
The good news though, is that we see a better correlation between pre-meal trigger and waist to height and BMI. Rather than worrying so much about your blood sugars after you eat, it seems that people who have a lower blood glucose before they eat tend to have much better metabolic health.
There is some variability across individuals due to different Personal Fat Thresholds. However, when we look at this person by person (e.g. Sue’s data below), we see that a lower premeal glucose trigger before you eat aligns nicely with weight and body fat levels.
Your waking glucose is one of the most reliable indicators of metabolic health and your risk of dying from any cause.
As shown in the chart below, pre-meal blood glucose trigger strongly correlates with your waking glucose. Rather than worrying about the rise in glucose after you eat, managing your glucose before you eat is much more useful if you actually want to lose fat and gain health!
To optimise body composition, you need to measure and manage the things that matter. Your blood sugar before meals is a much more useful metric that you can manage by optimising your meal timing and intermittent fasting routine.
Doesn’t WHAT I eat matter too?
Yes. WHAT you eat is arguably more important than WHEN you eat.
Data-Driven Fasting simply empowers you to optimise your food timing to ensure a negative energy balance.
- While high-fat foods and meals will keep your blood sugars stable, they also provide a lot of energy and lower satiety. Although your blood sugars and insulin levels may be stable, your body won’t need to draw down on your body fat for a long time until it burns up all the energy from that fat bomb or buttered coffee.
- Meals with more fast-digesting non-fibre carbohydrates will raise your blood sugars quickly, but they may return to below baseline more quickly.
- Foods that contain both fat and carbs together (and low protein) will fill your fat and glucose fuel tanks at the same time and allow you to eat more and keep your blood sugars elevated for longer.
- Foods with a higher percentage of protein and a greater nutrient density are harder to overeat and won’t raise your blood sugars significantly (in fact, they may reduce them). Your blood glucose will return to below target more quickly.
The bottom line
- Lower and stable blood sugar and insulin levels are a sign of good metabolic health, but managing the symptoms with a high-fat diet does not lead to metabolic health.
- The fundamental problem is not insulin toxicity. It’s energy toxicity.
- When you eat, rather than focusing on avoiding short term blood sugar and insulin spikes, you should focus on higher satiety nutrient-dense food that will reduce your cravings and allow you to lose body fat.
Data-Driven Fasting solves the energy balance problem and avoids the many pitfalls of calorie tracking.
By using your blood sugars as a fuel gauge to return to just below your personal trigger, you ensure a long term negative energy balance. Over time insulin, blood sugars, waist, body fat and improved metabolic health will follow.
If you want to find Your Personal Trigger you can download our free baselining sheet here or download our free 130-page Data-Driven Fasting Manual here to learn all about how you can use Data-Driven Fasting to fine-tune your intermittent fasting routine to optimise your pre-meal blood sugars.
We just wrapped up our first Data-Driven Fasting 30 Day Challenge with some amazing results! If you’re interested, our next 30 Day Challenge starts 5 September 2020. If you can’t wait until then, you might like to check out our Data-Driven Fasting Program to get started with Data-Driven Fasting right away.
|130 page manual||yes||yes|
|Phases||Access to all phases immediately.||Initial focus on Baselining and Hunger Training phases. |
Access to other phases at completion.
|Support||Self guided.||Facebook Group.|
|Delivery||Detailed program to guide you through each phase.||Daily Facebook posts with FAQs & Pro Tips.|
|Start||immediately||every six weeks|