how to use your blood sugar meter as a fuel gauge
- Chronically elevated blood sugar levels can be a sign that you are eating too much and/or too often.
- You can use your blood sugar to help you refine your meal timing to optimise your weight and blood sugar levels.
- Delaying your next meal allows your body to use up the stored energy in your bloodstream, liver and body fat stores.
Over the long term, a decreasing weight on the scale can be a good indicator that you are not overeating. However, in the short term, blood glucose levels can be a more useful indicator of whether you really need to eat now or if you are just eating because out of habit, boredom, entertainment or comfort.
The below table outlines a protocol that will help you to use your blood sugar meter as a fuel gauge to reach your diabetes and fat loss goals.
|greater than average, well slept and low-stress||delay eating and/or exercise to reduce glucose|
|less than average||if hungry, enjoy nutrient-dense foods that align with your insulin sensitivity|
|< 73mg/dL (4.0 mmol/L)||if hungry, eat higher insulin load foods and delay exercise|
This approach is not intended for people who do not produce enough insulin (i.e. type 1 diabetes, type 1.5, LADA and MODY) but rather for people who are insulin resistant and produce large amounts of insulin but still have high blood sugar levels (i.e. pre-diabetes and type 2 diabetes).
By contrast, reducing meal frequency enables blood sugar and insulin levels to decrease.
High levels of insulin keep fat stores from being used glycogen trapped in the liver while the energy in the bloodstream is used up.
When our adipose tissue can’t absorb any more energy, it becomes insulin resistant. This makes it harder for insulin to get into our major fat stores on the body. But your pancreas continues to ramp up insulin production in order to reduce high blood glucose levels in the blood and to keep the glucagon stores in the liver. With elevated insulin levels and more insulin resistant adipose tissue the excess energy now starts to get stored in more sensitive parts of the body such as our liver, pancreas, heart, brain and eyes.
Delayed eating allows the energy in the bloodstream to reduce. Once the liver glycogen stores start to be depleted, then the body finally turns to body fat for fuel.
Eating larger meals with more carbohydrate causes your blood sugar to stay higher for longer. Conversely, consuming smaller meals with a lower insulin load allows your blood sugar to return to baseline faster.
When to eat
Your blood sugar metre can be a useful tool to understand whether you really need extra energy or whether you could skip a meal or two or not eat for the day.
If you have some level of insulin resistance, then chances are your blood sugar levels will be higher in the morning due to liver glycogen being released as your body prepares for the day. This is sometimes referred to as Dawn Phenomenon.
If you are insulin resistant the insulin secreted by your pancreas doesn’t keep up with the release of glucose into the bloodstream, and hence your blood sugar will be high.
If you test your blood sugar in the morning and it’s higher than your current average, then you might want to delay eating until your blood sugar comes back down. This may mean eating your first meal early afternoon followed by an early dinner (i.e. 16:8 intermittent fasting). Alternatively, if you consistently find your blood sugars are high in the morning you could skip dinner avoid eating later in the evening, which would help to lower morning blood sugar.
There is no perfect fasting routine for everyone. Over time you’ll find one that suits you, and you will be able to calibrate your feeling of hunger with your actual need for food based on your blood sugar levels and reduce the frequency of testing. Once you’ve established new habits you will no longer need to rely on the glucose metre.
Some people find that they can ‘eat to satiety’. However, others find that they tend to overeat and ‘binge’ after a long period between meals, particularly on energy dense and nutrient poor hyper-palatable foods. Using a metric like your blood sugars is useful to make sure fasting is providing the outcomes you want. Tracking your glucose levels can help you ensure that your blood sugar levels are decreasing but not so much that you will lose control of food quality or quantity when you eat next.
Tailored just for you
Many people agree that intermittent fasting is a good idea, but many people get confused about what frequency is best for them.
How do you know whether you should be doing:
- Michael Mosely’s 5:2 diet,
- Hugh Jackman’s 6:8,
- Kiefer’s Carb Back-Loading and Carb Nite,
- Lyle McDonald’s TKD and CKD,
- Bert Herring’s Fast Five,
- Ori Hofmekler’s Warrior Diet, or
- Martin Berham’s Lean Gains?
There are so many options!
How do you know which one is right for you?
How can you tell if it’s working?
How can you refine and tweak to reach your goals?
What if you just really feel hungry but it’s not “time to eat” yet!?!?
The advantage of using your blood sugar level as a guide versus a regimented intermittent fasting protocol or a fixed calorie intake is that it accounts for the energy your burn as well as what you’re eating.
You could argue that tracking your blood sugars could be more useful than calorie counting. Ensuring that your blood sugars are decreasing by delaying eating will ensure that you are running at an energy deficit and pulling fuel from the energy stores on your body.
The body is a complex adaptive system, and our energy expenditure will vary based on many factors beyond our ability to measure and manage.
Eating is not bad. You need to balance your intake with your energy expenditure while getting the nutrients you need to thrive. This can be a challenge when we are surrounded by cheap hyper-palatable nutrient-poor foods.
Refining your feasting/fasting route around your blood sugars will help you to fine-tune when and how much you eat to your actual requirements.
Your blood sugar meter can help you understand whether your hunger is real and help you to refine your eating regimen.
If your blood glucose levels are lower than your average, then your insulin levels will be decreasing, and you’ll be using up your stored body fat and liver glycogen.
If your blood sugar levels are increasing, then it’s likely you’re overeating and/or too often which means you’ll be storing energy as fat on your body.
When using this approach, you can eat to eat to satiety. But if you overdo your intake at this meal it will mean that you will be delaying your next meal a little longer.
You could even use this approach to make sure you don’t overdo the refuelling and keep the insulin load of your meals such that your blood sugar doesn’t go over say 120 mg/dL (or 6.7 mmol/L). A blood sugar level above this is a sign that your liver glycogen stores are full and spilling over into your bloodstream.
Some people find that they tend to eat less overall when intermittent fasting compared to trying to eat numerous ‘small’ meals. Saint Augustine wisely said:
“Complete abstinence is easier than perfect moderation.”
I think this also applies to our meal timing and portion sizing.
In the study Adherence to hunger training using blood sugar monitoring: a feasibility study, the researchers found that participants did much better when they set their own personalised blood sugar target rather than waiting until their blood sugar levels reached some optimal target before eating.
The other noteworthy observation from this study was that people who were obese lost a significant amount of weight!
Overweight participants achieved significant weight loss over the two-week period, with an average loss of 1.5 kg (95 % CI 2.2, 0.9) and a corresponding reduction in BMI of 0.6 kg/m2 (95 % CI 0.3, 0.8), p < 0.001). By contrast, lean participants maintained their weight.
The end game
The long-term goal is to achieve an optimal HbA1c of 4.5% which equates to an average blood sugar level of 83 mg/dL (or 4.6 mmol/L).
People with Type 1 Diabetes following Dr Bernstein’s protocol try to keep their blood glucose within ten points of the optimal target level of 83 mg/dL (4.6 mmol/l). This means that they will dose with insulin when their blood glucose rises above 93 mg/dL (or 5.2 mmol/l) and then eat to bring their glucose levels back up when they drop below 73mg/dL (or 4.0 mmol/L).
Someone who has a functioning pancreas but is struggling with insulin resistance, hyperinsulinemia and/or obesity can use a similar process to manage their blood glucose and insulin levels. However, rather than dosing with insulin to bring their blood glucose down they simply delay eating until they burn through the excess glucose in their bloodstream.
Waiting to eat until your blood glucose levels are below your recent average will ensure that they are decreasing over time. Most glucose meters will display the average glucose level for the last seven, fourteen and thirty days, so it is easy to tell what your current target is.
On the Freestyle Lite metre (our family favourite) you can show your 4, 14 and 21-day average blood sugar by pressing the ‘m’ button on the left-hand side of the metre.
If you’re eager, you could go to the trouble of graphing your blood sugar numbers, However, in the end, if your seven-day average is less than your fourteen-day average then you’re moving in the right direction.
Over time you want to see your average blood glucose levels coming down. If you find your blood glucose levels drifting up, it’s a sign that you need to intensify your fasting regimen.
If working out your average blood sugar level is a bit complex you can just set an arbitrary target of say 10 mmol/L on waking. If after a while you find you are mostly under waking under 10mmol/L you can change your target to 9.0 mmol/L, then 8.0 mmol/L, then 7.5 mmol/L, then 7mmol/L and so on.
Normalising blood sugar and insulin will often help people to lose weight, particularly if you’re insulin resistant. However, some people will still need to pay attention to continuing to lose weight once their blood sugar and insulin is normalised.
Will optimal blood glucose levels guarantee weight loss?
While normalising blood sugars and insulin sensitivity will usually help you improve your body weight, it is possible to have excellent blood sugars and still be overweight (e.g. by eating a lot of fat that doesn’t raise blood sugar but doesn’t allow body fat to be burned).
The chart below shows Rebecca Latham’s blood sugar levels decreasing over a period of three months. Once your average blood glucose level drops below 83mg/dL or 4.6mmol/L, then you may do better switching to using a weight target rather than a glucose target to drive your eating frequency.
If you have achieved excellent blood sugar and still want to lose weight, you can transition to using your target body weight as a trigger to decide whether to eat that day as detailed in the article How to use your bathroom scales as a fuel gauge.
The chart below shows Rebecca’s weight loss to achieve her goal over twelve months and then transitioning to a maintenance regimen during 2017.
When not to use this approach
Exercise may raise your blood sugar in the short-term due to the body dumping glycogen from your liver into the bloodstream to fuel your activity. If you don’t eat before or after exercise, your body will have to replenish the glycogen stores from the energy stores on your body.
There will be times when you’re hungry, or it will be appropriate to eat for social reasons such as a party, family gathering, etc. Periodic fasting and then feasting is a regular part of our culture. Tracking your blood glucose levels will help you get back on track after these indulgences. Personally, I tend to employ this approach after feasting periods such as Christmas to recalibrate my appetite.
You should also keep in mind that other things affect blood sugar including stress, sleep, sickness, hormones and exercise that you will need to be mindful of when deciding whether to delay a meal due to your blood sugar being high.
Fasting may not be ideal if you’re stressed, sick, not sleeping well and/or are pushing the exercise envelope. During these times, it may be better to focus on life maintenance and listen to your appetite and leave your fasting until the rest of your life is under control.
If you are taking insulin or other blood sugar lowering medications, you will need to make sure they are reduced to make sure your blood sugars don’t drop too low. Otherwise, you may have to eat to raise your blood sugar due to the excess medication.
The problem with injected insulin or many other diabetes medications is that, while it may help to reduce blood sugar levels, it also drives the energy back into the cells rather than allowing the stored energy to flow out of storage.
The more you reduce insulin (injected or produced from your own pancreas) to normal healthy levels the quicker the healing can occur. However, at the same time, it would be prudent to reduce medications progressively to prevent your blood glucose levels from going too low.
High blood sugar levels can be a sign that you’re stressed, exhausted or your hormones are out of whack (including time of the month for females), all of which will lead to insulin resistance. You can use Heart Rate Variability to track your stress and exhaustion with an app such as Elite HRV which enables you to see when you’re exhausted and need to back off and rest.
If you just don’t feel like fasting and your blood sugar levels are high it’s probably a sign that you need to rest, relax, sleep, meditate, see some real sunlight during the day and stop gazing into the artificial sun on your devices before you go to bed. Using f.lux on your computer or blue blocking glasses after sunset is worth considering.
While longer therapeutic fasts can be beneficial, a shorter duration feast / fast cycle that brings your blood sugar levels down to below your average is likely to be more useful to improve your metabolism while reducing the extreme swings in water weight or any concerns that you’re not getting adequate protein to support lean body mass.
Will monitoring my blood sugars help me enter ketosis?
The most straightforward approach is just to measure your blood sugar levels when you feel hungry and not eat until they drop below your target level. You could still use this method even once you have improved your insulin sensitivity to losing weight by targeting even lower blood glucose levels before eating.
The chart below shows the sum of blood glucose and blood ketone levels for people on a low carb or ketogenic diet. While a low carb diet helps to stabilise blood sugar and removes hyperpalatable foods when benefits a many people in terms of weight loss and energy levels, some of the major benefits are reserved for the periods when we are in a low energy stage (e.g. reduced insulin levels, autophagy, mitochondrial biogenesis, increase in NAD+ and increase in SIRT1). It is in these periods of low energy that our body goes into cleansing and repair mode so it can survive through the famine to be able to reproduce in the next time of plenty.
Zooming in on the left hand side of the chart, we can see that it’s the periods when we drive the energy in our blood down through delaying eating or restricting energy intake that we get the major benefits often associated with a low carb or ketogenic diet.
You will likely have some blood ketones in your bloodstream when your blood glucose levels are low, but they may not be at the levels that many consider to be ‘optimal ketosis’. As shown in the chart below, if your blood glucose levels are at 4.5mmol/L or 80 mg/dL then you you might expect blood ketone levels to be somewhere between 0.3 and 0.7mmol/L. If your blood sugars are at 4.9mmol/L or 88 mg/dL your ketones might be somewhere between 0.4 and 1.1 mmol/L.
While measuring ketones can be interesting, they tend to be a much noisier measurement. As the glucose in your blood reduced your body will be forced to turn to your body fat stores, so you will increase your fat burning. Part of the reason that you may not see high levels of ketones in your blood though is that they are being used efficiently for fuel and not backing up in your bloodstream. So if you have limited funds for test strips and don’t want to be pricking yourself too often then I would focus on blood glucose levels.
Ketones and the glucose: ketone index
Monitoring your blood sugar will work whether you are insulin sensitive or insulin resistant, obese or healthy weight.
The body does a fantastic job of replenishing your glycogen stores and stabilising your blood glucose whether it be from carbohydrates, gluconeogenesis from amino acids or even gluconeogenesis of fat once you are highly insulin sensitive.
If you require therapeutic levels of ketosis, once you are starting to get your blood sugar levels under control, you could begin to track your ketones or the glucose: ketone index (GKI). Decreasing glucose along with rising ketones is a sign that your glycogen stores are being depleted, your insulin levels are reducing and you your hunger is a signal that you really need food.
Tracking the ratio between your glucose and ketones (GKI) and delay eating until your GKI is under a certain level could be a useful strategy if you are aiming for therapeutic ketosis for the management of chronic conditions such as cancer, Alzheimer’s, Parkinson’s or dementia.
Alternatively, you could simply not eat until your ketone levels were higher than a certain threshold. You could start with a target ketone level of 0.4 mmol/L and keep winding that up till you achieve your desired results.
However, testing blood ketones every time you feel hungry could be expensive. Many people also find that their blood ketone levels tend to decrease as they adapt to a low carb diet.
While all these things are relevant and useful, make sure to use them as tools to help you live life rather than taking over your life and stressing you out. Your goals need to be realistic and tailored to your situation. Hopefully, in time this ‘hunger training’ approach will help you build new habits around eating which will mean you won’t need to rely on the testing.
Fast well. Feed well
Keep in mind if you are eating less food less often you will need to maximise nutrient density when you do eat, including ensuring that you are getting adequate nutrients to maintain lean muscle mass over the long term.
Some people advise refeeding with high-fat ketogenic foods after a fast. While they may help keep insulin levels lower, it may not enable you to replenish the micronutrients that you lost during your fasting (particularly the minerals such as potassium, magnesium and sodium and the amino acids). It also may not be optimal to refeed on very high-fat foods if you are trying to lose body fat. Foods with adequate protein and high levels of nutrients will also be more satiating and enable you to be ready to fast again sooner.
I know personally, I tend to reach for the energy dense nutrient poor foods after a period of fasting. That’s why I developed that Nutrient Optimiser to help you fine-tune your diet based on your current level of insulin resistance.
The chart below shows a comparison of the nutrients / 2000 calories in all the foods in the USDA foods database versus the most nutrient dense foods identified by the Nutrient Optimiser algorithm. If our goal is weight loss, then these foods can be beneficial to ensure we get the nutrients we need with the minimum amount of energy.
I think what we really want when we refeed is to maximise the nutrients : energy ratio of the food we eat so we can maximise our fat loss goals and be able to fast again soon without risking nutrient deficiencies. After a period of fasting and autophagy, we want to refeed on nutritious food that will help us build back a strong, healthy body.
Best of luck if you chose to try this approach. I look forward to hearing how you go.
post last updated January 2018