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If your first reaction to “intermittent fasting with type 1 diabetes” is “Oh my gosh, my blood sugar would be so low! I could never do that!” then definitely keep reading.
In this guide, I will cover everything you need to know about intermittent fasting with type 1 diabetes.
Table of Contents
- What’s the point of intermittent fasting?
- A note on blood sugar levels
- Special precautions
- How intermittent fasting works
- What an intermittent fasting schedule looks like
- But won’t I be hungry?
- But isn’t eating breakfast really important?
- How to do intermittent fasting with type 1 diabetes
- Frequently asked questions
- Why I love intermittent fasting as a mom
- Final thoughts: should you try intermittent fasting?
What’s the point of intermittent fasting?
Intermittent fasting has gained attention for its potential in managing type 1 diabetes alongside traditional treatment methods. This approach may offer several benefits, supported by emerging research:
Reduced risk of hypoglycemia
Fasting could help decrease episodes of hypoglycemia in type 1 diabetes by allowing for more predictable blood sugar levels due to reduced frequency of meals.
Enhanced fat metabolism and blood sugar management
Intermittent fasting may improve fat metabolism and lower glycemic variability, contributing to more stable blood sugar levels.
Increased insulin sensitivity
There’s evidence to suggest that intermittent fasting can improve insulin sensitivity (how responsive the body’s cells are to insulin) and reduce glucose production by the liver.
Weight management
By helping with weight loss and improving body composition, intermittent fasting can play a role in managing the additional challenge of weight gain that is often associated with certain diabetes treatments.
Thoughts on the use of CGM
For people with type 1 diabetes, using a continuous glucose monitor (CGM) during intermittent fasting can provide valuable insights into blood glucose patterns, helping to identify periods of potential hypoglycemia (low blood sugar) and adjust fasting schedules accordingly.
It’s worth noting that while intermittent fasting shows promise, it’s important for people with type 1 to proceed with caution and under medical supervision. Adjustments to insulin regimens and careful monitoring of blood sugar levels are essential to avoid negative effects such as hypoglycemia.
As research continues to evolve, the use of intermittent fasting as part of a diabetes management plan should be personalized and based on feedback from healthcare providers.
A note on blood sugar levels
Before we get started: If your blood sugar drops just because you don’t eat for a handful of hours, you’re likely taking too much basal (background) insulin via pump or injection. Talk to your certified diabetes care & education specialist (CDCES) or primary care physician about “basal testing.”
(Or check out the book Think Like a Pancreas by Gary Scheiner, MS, CDCES, and do the basal testing yourself.)
Basal testing consists of purposefully skipping a meal (or two) to see if your insulin keeps your blood sugar steady or if your blood sugar significantly rises or falls out of your personal goal range.
As a general rule, if it rises, you’re not getting enough basal insulin. If it falls, you’re getting too much.
Special precautions
Before we discuss the nuts and bolts of intermittent fasting, an important note: If you have diabetes and are thinking about trying this approach, speak with your healthcare team first.
They can help you with strategies to avoid potential complications such as hypoglycemia, hyperglycemia (high blood sugar), dehydration, and diabetic ketoacidosis (DKA, a serious diabetes complication that can occur when blood sugar levels have been too high).
They can also assess if you have any conditions that increase your risk with intermittent fasting, advising whether you should avoid or postpone this approach. (The Association of Diabetes Care & Education Specialists [ADCES] has published four risk categories of fasting for people with diabetes.)
Those who have type 1 diabetes and are not in target range, for example, are considered very high risk.
How intermittent fasting works
When you wake up with an in-range blood sugar (ideally between 70 to 130 mg/dL [3.9 to 7.2 mmol/L] as a person with type 1 diabetes — 130 mg/dL being on the higher end but offering some room for imperfection in a complex disease) and you don’t eat breakfast, which means you don’t take a bolus of insulin, your body will continue to burn fat for fuel.
This is because you have yet to introduce a new supply of glucose from food. You have yet to turn on that switch telling your body to rely on glucose for fuel instead of fat. The moment you eat or drink something containing calories, your body says, “All right! Now it’s time to burn glucose!”
Intermittent fasting takes advantage of this physiologic process by alternating periods of fasting with periods of eating.
What an intermittent fasting schedule looks like
There are a lot of different ways you can approach intermittent fasting, and after doing this myself for several years on and off, I’ve found I can flexibly create my own approach that feels most natural to me.
Types of intermittent fasting
There are a variety of different types of intermittent fasting, such as time-restricted fasting, overnight fasting, alternate-day fasting, circadian rhythm fasting, and periodic fasting.
For people with type 1 diabetes, intermittent fasting presents both opportunities and challenges. While some preliminary research suggests possible benefits, careful planning and monitoring are essential.
Here are several of the most common fasting schedules:
Time-restricted fasting (e.g., 12- or 16-hour fasting)
Eating all meals within a specific time window each day, often resulting in a daily fasting period of 12 to 16 hours.
It’s important to note that you should still eat a normal day’s worth of calories during the eating window.
If you’re trying to lose weight, that amount of calories might only be, say, 1300 to 1600, but you still need to get your allotment of calories and nutrients while following a fasting program.
24-hour fasting
Going without food for a full 24 hours, once or twice a week, from, say, dinner to dinner. This should generally only be performed once per week.
(Read this guide from John Berardi, PhD, and colleagues to see what happens if you do a 24-hour fast too often.)
Alternate-day fasting
Alternating days of regular eating with days of either complete fasting or significant calorie reduction.
Circadian rhythm fasting
Aligning fasting periods with the body’s natural circadian rhythm, such as incorporating nighttime fasting. This method involves eating the day’s meals within daylight hours and fasting during the night, which can potentially support metabolic health.
Periodic fasting
Selecting specific days for fasting each week or month.
For example, in the 5:2 method, individuals might eat normally for five days and then choose two days to significantly reduce calorie intake. This method can offer flexibility and has been explored for its potential benefits in weight management and metabolic health.
However, for people with type 1 diabetes, it’s important to approach periodic fasting with caution, considering the need for consistent carbohydrate intake to manage blood glucose levels and prevent hypoglycemia.
Moving forward
Research into intermittent fasting and type 1 diabetes is extremely limited. However, recent explorations have begun to shed light on its potential benefits for weight management and metabolic improvements in people with type 1.
Initial studies, such as a pilot study (a “small-scale test of the methods and procedures to be used on a larger scale”) published in Obesity Medicine, have shown promising results in terms of safety and effectiveness, suggesting that carefully monitored intermittent fasting may offer a viable strategy for weight loss without increasing the risk of negative events like hypoglycemia.
Similarly, a narrative review in Nutrients highlighted intermittent fasting’s potential to enhance insulin sensitivity and reduce blood sugar variability.
In early 2024, researchers at the University of Illinois Chicago started a pilot study that will eventually provide data on how time-restricted eating compares to calorie counting in people with type 1 diabetes.
However, it’s crucial to note that research in this area is still in its early stages, particularly regarding the long-term effects and best fasting protocols for people with type 1 diabetes.
Therefore, while intermittent fasting presents an interesting potential avenue for dietary management in type 1 diabetes, further clinical trials are necessary to fully understand its impact and safely integrate it into treatment plans. It’s important to consult the latest research and healthcare professionals for guidance.
But won’t I be hungry?
Guess what — it’s OK to be a little hungry. After you stop worrying about your belly not feeling full 24/7 and push through it (being sure to keep a close eye on your blood sugar levels), around 10 a.m., you might actually notice that you feel a little bit awesome. A little more clear-headed, a little more focused, maybe with even a little more energy.
Drink some water — it’s good for you anyway — and embrace that feeling of your body just being empty. Yes, there are many ways to lose weight by eating every 3 to 4 hours, but that’s not the only way to eat, and it’s not the only way to lose weight.
Are you someone who is always thinking about their next meal? Always snacking?
As Dr. Berardi explains, “Intermittent fasting can be helpful for in-shape people who want to really get lean without following conventional bodybuilding diets, or for anyone who needs to learn the difference between body hunger and mental hunger.”
For athletes and people engaged in intense exercise, individual energy needs and responses to fasting can vary.
While some may perform well under an intermittent fasting regimen, others might find they need more consistent fueling to maintain peak performance. It’s important to listen to your body and consult with a healthcare professional to find the approach that works best for you.
But isn’t eating breakfast really important?
Eating breakfast can absolutely be a crucial part of weight loss and maintaining a healthy metabolism, but it’s not the only way, according to some experts.
“There haven’t been any conclusive studies that found eating breakfast to have a positive effect on weight loss or weight maintenance,” explained sports nutritionist and registered dietitian Leslie Bonci, MPH, RDN, CSSD, LDN, in Popular Science in 2017.
Also, the idea that skipping breakfast causes weight gain is oversimplified and not necessarily true. It may not be the act of skipping breakfast itself that can cause weight gain. In studies that have observed this effect, a large majority of those who skipped breakfast also lacked other healthy habits overall, which may instead have resulted in the weight gain.
“It could be that eating breakfast is simply a marker of a healthy lifestyle and, in itself, doesn’t protect against obesity,” explains a 2016 article on the website ScienceAlert.
And more recent research has continued to present mixed results on the importance of breakfast for weight management.
A 2019 systematic review and meta-analysis (analysis of data from several studies) published in The BMJ indicated that the impact of breakfast on weight and energy intake varied. This study, which looked at several randomized controlled trials, suggested that there wasn’t a clear-cut effect of eating or skipping breakfast on weight loss.
The results indicated that the general recommendation to eat breakfast might not have a universal impact on weight management. These findings highlight the complexity of dietary habits and their effects on weight, suggesting that individual dietary preferences and lifestyle choices play a significant role in weight-management strategies.
How to do intermittent fasting with type 1 diabetes
First off, be sure to get the all-clear from your doctor before you give intermittent fasting a try when living with any type of diabetes.
Using a CGM can help pinpoint when you’re at risk for hypoglycemia, making it easier to understand how your blood sugar responds to meals and fasting periods.
As you adapt to intermittent fasting, you may find a sense of mental freedom, especially if you have type 1 diabetes. This is because there’s less concern about experiencing high or low blood sugar levels after skipping breakfast.
Research indicates that intermittent fasting can influence insulin sensitivity and blood glucose stability, including in people with type 1 diabetes.
While some studies suggest that fasting can lead to more predictable blood sugar levels due to reduced meal frequency, it’s important to be aware that individual responses can vary widely.
If you stick to your fasting program consistently, you’ll likely find you lose weight and therefore increase your insulin sensitivity. This means you’ll be able to decrease your basal insulin rates, which is a good thing.
This is part of weight loss with diabetes, but if you aren’t expecting it, you’ll be annoyed and frustrated with the low blood sugars, so be prepared.
How to adjust high or low blood sugar when fasting
Waking up with an in-range blood sugar is extremely helpful, but obviously, we’re not perfect and things happen. Here’s how to manage your plan for fasting if your blood sugar is not in your ideal range when you wake up:
- If you wake up a little high, sure, you can take a reduced correction dose (read Think Like a Pancreas or speak with your healthcare team for more information on determining your correction dose) and carry on with the fast, but be aware that introducing that bolus of insulin could be enough to switch on your body’s need to burn glucose for fuel.
- For legitimate “dawn phenomenon” high blood sugars, you may simply need a bolus correction of insulin every morning that really is part of your “basal” insulin dose but is applied via pump or injection as a bolus. If this prevents morning fasting highs, it’s part of your fasting regimen. Learn more about managing the “dawn phenomenon” here.
- If you don’t take that correction dose of insulin, then you’re just spending the next several hours with a high blood sugar, which is counterproductive (and potentially dangerous) if our overall goal is health … right? So, definitely take the insulin you need in order to be at your target blood sugar levels — that’s your first priority.
- If you wake up low, then you obviously have to eat and fasting is no longer going to work. You’d be better off eating a healthy breakfast, fueling your metabolism since it’s already burning glucose for fuel, and trying again tomorrow.
- Similarly, if you develop hypoglycemia during a fast, break the fast immediately and use your hypoglycemia treatment plan to bring your levels back into target range. Remember the 15-15 rule, which recommends having 15 grams of carbs, checking your blood sugar after 15 minutes, and repeating if it’s still low. Also be sure to have a glucagon treatment on hand in the event of severe low blood glucose.
- If you routinely wake up with blood sugars that are too high or too low, you need to go back and do some basal testing or test the insulin-to-carbohydrate ratios that you’re using for the food you eat before bed.
- An additional sneaky blood sugar issue to keep in mind: If this applies to you, it’s necessary to stop binge eating late at night. If you’re currently up at midnight eating yourself out of house and home, focus on this first before pursuing intermittent fasting. People often blame high blood sugars in the morning on the dawn phenomenon when it’s actually the result of late-night binge-eating.
It’s not a magic trick. It’s not a fad. It’s just basic science of how the body responds in a fasted state.
Exercising in the morning when fasting … is actually easier (in my experience)
When you’re fasting during your exercise, it’s generally observed that aerobic or cardiovascular activities tend to lower blood glucose levels, which makes sense given the muscle’s increased use of glucose for energy.
However, certain exercises, especially those that are high-intensity like weightlifting, can trigger a rise in blood glucose. This is partly due to the body’s stress response, releasing hormones like adrenaline, which in turn prompts the liver to release more glucose.
You may therefore find that with weightlifting or other anaerobic workouts, you might actually need a bolus of insulin for that type of workout.
This will not take away from your fasted efforts — this simply helps use the glucose that’s produced when glycogen stored in your muscles is broken down during anaerobic exercise.
It’s important to find the right balance for managing blood glucose levels during different types of exercise and to consult with your healthcare team as needed for guidance.
I LOVE fasted cardio! In fact, I make sure that all of my exercise sessions happen either fasted in the morning or fasted in the evening (by not eating anything after 1 p.m. and then getting on the treadmill around 7 p.m.).
This ensures that all bolused rapid-acting insulin is well out of my system. It works. When I used to lift weights, I did find that I needed 1 unit of insulin in the morning if I was doing a fasted weightlifting workout.
So in a nutshell:
- Wake up with an in-range blood sugar (or correct a slight high with half of your usual correction);
- Begin your workout while fasted, or if managing fluctuating blood sugars is challenging, consider scheduling your workout for a different time;
- Check your blood sugar halfway through your workout for safety’s sake;
- If your anaerobic workout proves to typically raise your blood sugar, take half of what you would take to correct that high — but take it when you start exercising to prevent the high in the first place;
- If your workout is aerobic (cardio), just continue your workout — you shouldn’t see a rise in blood sugar from aerobic fasted exercise, but be aware that you will be at greater risk for hypoglycemia;
- Check your blood throughout your workouts if you’re not using a CGM;
- Shower (thank you), and enjoy the rest of your fasting.
Frequently asked questions
Is intermittent fasting safe for people with type 1 diabetes?
For people with any type of diabetes, attempts to try intermittent fasting should be done only with the guidance and feedback of your physician.
In many cases, it appears to be safe. But you need to speak with your healthcare team to make sure that you don’t have any other conditions for which intermittent fasting is contraindicated and that your insulin doses and medications are properly tuned.
For people with type 2 diabetes who typically take morning medications to lower blood sugar, it’s advisable to consult with your doctor about taking the medication with the first meal of the day instead of the usual morning schedule if you’re planning to fast in the morning.
With your doctor’s OK, this adjustment can help you better manage blood sugar levels in accordance with the altered eating schedule.
For people with type 1, as discussed extensively above, your insulin doses should be finely tuned (even if you don’t ever plan to fast) so that you can miss meals and your blood sugar is generally steady and in a healthy range.
Adjusting your insulin doses to meet this standard is called “basal testing.” If you’ve never done any basal testing to assess the accuracy of your personal insulin doses, definitely do that first. And do it even if you don’t ever intend to fast. It’s essential to diabetes management.
During your first week of fasting, check your blood sugar often during your fasting window to see how your body responds. If you stick with it long-term, you’ll likely find you will need to reduce your basal rates (even within a week or two) because intermittent fasting often has the fantastic benefit of increasing your sensitivity to insulin.
What can you drink during intermittent fasting?
During the timeframe that you’re not eating calories, you shouldn’t be drinking any calories either. Black coffee or tea or water or seltzer (or diet soda, if you must) are all safe to drink.
While I lean toward minimizing artificial sweeteners and opting for natural hydration sources like water, it’s essential to recognize that health and nutrition are highly individual.
Although some concerns exist around artificial sweeteners, including their impact on health, the scientific community’s views on this are varied. It’s always best to consult healthcare professionals for advice tailored to your needs.
Read your labels carefully, and when in doubt, reach for some all-natural plain water.
Be sure to drink enough water to avoid dehydration, one of the potential risks of intermittent fasting.
Do you need to do intermittent fasting if you already follow a ketogenic diet?
You’re obviously going to be burning more fat than the rest of us after eating a ketogenic breakfast, but even some of that breakfast will be converted to glucose and require a bit of insulin to digest, so intermittent fasting still applies to keto-folks, too.
Although there is currently very limited research data on adding fasting to an already disciplined ketogenic diet, my personal hunch is that it would likely help with weight-loss progress.
Just beware, however, that if you don’t already understand how to eat enough on a ketogenic diet, adding fasting to the mix can be a recipe for a binge during the eating period of your fasting plan.
I highly recommend studying and practicing ketogenic eating for a few months before adding fasting to it. It’s very common for new low-carb eaters to eat too little because they are still afraid of eating too much fat. (And fat, as you’ve probably heard, is a pretty crucial part of a successful ketogenic diet.)
Why I love intermittent fasting as a mom
I can wake up in the morning, drink a cup of black coffee and guzzle some regular ol’ water, then pack our bags and head out the door to the playground or playgroup or the library. I can chase my kids around all morning long and I don’t have to worry about my blood sugar.
If I woke up at 90 mg/dL (5.0 mmol/L), I know my blood sugar is still in that zone.
I don’t have to spend any time making my own breakfast. Or trying to find the time to make my own breakfast. I don’t have to worry about getting real, healthy food into my own belly until we come home from our morning activity, and I get the kids lunch and get everybody settled.
(If you’re not a mom of two children, let me tell you that finding time for your own breakfast is actually incredibly challenging some days amongst the diaper changes and the bottles and playtime and the … on and on and on! When that second kid pops out, parenting is ON in full-power mode, 24/7.)
By 1 or 2 p.m., I’m not starving, and I actually feel pretty energized after that morning fast. And making myself a healthy meal feels very doable because the busiest part of the day is behind us.
Final thoughts: should you try intermittent fasting?
If all of the above sounds appealing to you, talk to your doctor about giving it a try! (And remember that intermittent fasting won’t be appropriate or effective for everyone with type 1.)
A few things to keep in mind when embracing intermittent fasting with type 1 diabetes:
- Do you currently have a healthy relationship with food? If not, I would address that first. Fasting is not ideal for the yo-yo dieter or someone trying to recover from an eating disorder. Check out my books Emotional Eating With Diabetes or Dealing With Diabetes Burnout to get started.
- Take good notes! The first week you try fasting, write down the insulin you took before bed, what your blood sugar was in the a.m., etc., so you can pinpoint any diabetes-related variables that are causing lows or highs in your blood sugar during the fasting period. For example: If you’re still up at midnight eating chips and ice cream, you can absolutely bet that will raise your blood sugar during the hours of 6 a.m. to 12 p.m. when you’re fasting. Some people blame the dawn phenomenon for what is actually late-night binge eating.
- During the first few fasts, check your blood sugar more often. Even though fasting itself shouldn’t cause low blood sugars, your insulin doses simply might not be appropriate. And nothing will reveal that sooner than fasting. Check your blood sugar often and take good notes. Learning how to study and adjust your insulin doses is a crucial part, I believe, of long-term success in life with type 1 diabetes.
- It offers flexibility: Occasional deviations, like indulging in breakfast when you’re truly hungry or during special family outings, don’t derail its benefits. It’s about finding a balance that works for you, listening to your body, and not stressing over the occasional exception. It’s crucial to stay consistent with the program, but understanding that life’s unpredictability sometimes calls for adaptability. It’s not a big deal! Make it work for you. Follow the program as much as you can, and don’t freak out when life gets in the way.
- You may find it useful to embrace fasting for a few months, then go back to a normal schedule. I’ve found that intermittent fasting has been really wonderful for me for several months at a time. Then I take a break from it for a couple of months, and eventually I naturally feel ready to follow that schedule again. Listen to your body and stay in close contact with your healthcare team to find what works for you.
- Be patient with your weight-loss journey, recognizing it as a long-term commitment rather than a quick race. If you find yourself breaking your fast prematurely to eat one of those darn office muffins, remember it’s part of the learning process. I’m a big believer that creating your own life around nutrition is a very long work in progress. Be constantly open to evolving, learning, trying new things, and never never never shaming yourself for being imperfect. It’s one big science project. Enjoy the project, stop punishing yourself, and learn to love the food you eat. Food can be fun, even when you’re trying to lose weight!
Learn. Study. Experiment. Repeat!
Update: I recorded this video in which I talk more about why I do fasted cardio, how I do it, and the benefits. Please let me know what you think in the comments below.
Bella
Hi. I’m trying to do If from 10-6 every day.
Type 1 diabetic. My question. If I go low and drink juice does that mean my fast is “wasted “ and should start again tmw? Also – I’m doing hiit three x a week and cutting Carbs but really don’t see Weight loss or my strength Improving. Still get tired. My eating is a bit all over the place so that could be why. However I’ve seen people “starve “ themselves and loose Weight. Why isn’t that the case for me? What is the best way to eat to loose Weight ( keeping in mind I do hiit and am ok w doing hiit)? Also is it effective to just do
If a few times a week and still see results ?
Christel Oerum
It’s fairly individual what weight loss regime works for different people, but most important is that it has to be something you can stick with. There is no magic plan except for being in a (reasonable) calorie deficit and sticking with it. Many don’t see any significant results until 3-4 weeks in, it’s about consistency and not jumping from one plan to the next. Just because you fast doesn’t mean you’ll lose fat. Try tracking what you eat during you “eating” hours and make adjustments based on that. If you’d like to read more about losing fat with T1D check out a detailed guide HERE
Ginger Vieira
Bella! Just to add to Christel’s response. Yes drinking juice means your fasted program for that day comes to an end because you’ll definitely be burning glucose for fuel after that. But that’s just life with type 1. It happens. I try to brush it off and do my best to make it work the next day!
Elizabeth
By what percentage should one reduce their long acting insulin? And which doses? I would be fasting from morning til dinner time?
Christel Oerum
That will really depend on your sensitivity and current usage. Dosing isn’t something we can advise on, but start conservatively (to be safe) and optimally work it out in collaboration with your medical team
Daniel
Interesting read! I do have a question regarding how the body will use/transfer fat for fuel. In my understanding the body requires insulin to be able to use glucose as fuel (if not then you spike) so my question is if insulin is needed to use glucose as fuel is insulin NOT needed in the body to use fat as fuel? How do fatty acids get into your muscles for fuel w/o insulin?
Ginger Vieira
Hi Daniel!
We all need insulin in our bodies 24/7 in order to survive. That’s your basal insulin in your pump OR your injection of long-acting insulin (Lantus, Tresiba, Levemir, Toujeo, etc.)
Fasting works because when you haven’t eaten in 8+ hours, and you continue to not eat, that means you aren’t taking a BOLUS (vs. basal) of insulin to cover the carbs/fat/protein in the food you’re eating. The moment you eat and take the insulin necessary to use that food for fuel or store excess as body fat/glycogen, your body is now burning primarily glucose for fuel, including when you’re performing cardio exercise. If you DON’T eat breakfast and you continue your fast (having not eaten since the night before), your body is burning body fat primarily for fuel but you do still have your basal/background insulin working to keep your blood sugars stable.
Let me know if that clears this up for you. I can assure you I didn’t come up with this theory/science on my own. It’s well established in the physiology of the human body. Fasted exercise has been used by athletes in the bodybuilding world for decades and decades because it so easily targets body fat for fuel.
Holler back with any questions!
Elly
Hi! I have done if for 10 days and out of them i worked out 7 days. I didn’t lose any weight even on 1300 calories. Could it be because I take long acting insulin morning and night ?
Christel Oerum
Hi Elly – weightloss is not linear and you can’t necessarily expect a large fat loss in only one week. A lot could be going on, you might be eating too little or not the right combination of things, you could have gained water weight, muscle etc. You’ll only gain weight from insulin (even morning and night) if you take too much and need to eat additional calories to keep your blood sugar up
Jessica
Hi! I’m just now starting to read about intermittent fasting. I’ve read that 16 hour fast and an 8 hour eating period is ideal. Obviously as type 1, you can’t go 16 hours without insulin. I’m going to try fasting breakfast & mid morning snack and then take my insulin (fast acting & basal). Is that basically what you’re saying? Is there any benefit if you do the 16 hour fast/8 hour eating period, even if you have to take your basal insluin? What fat loss benefits are there for only fasting breakfast before taking insulin for the day?
Ginger Vieira
Hi Jessica!
Fasting doesn’t mean you’re without insulin. You should still be taking your long-acting insulin or your basal insulin via a pump as normal. If your blood sugar drops low during your fast, that means you’re getting far too much basal insulin. In diabetes world, this is actually a purposeful “basal test”…
http://integrateddiabetes.com/basal-testing/
Ideally, a 16/8 hour fast is ideal if you eat dinner as usual. Go to bed. Wake up the next morning and don’t eat until 1pm. You would still continue your basal insulin per usual. So you would eat your breakfast meal at 1pm.
Does that make sense?
eric
Does it matter if you take your basal insulin in the morning even though you are fasting?
Christel Oerum
No, you should still take your insulin. If it’s titrated correctly you shouldn’t go low/high despite doing IF
Krissy
I’m so excited to find your site!
I’m a T1D for 32 years, pump/CGM user and self adjust/micro-manage basal/ratios etc. The ONLY time I’ve ever been able to lose weight was when breastfeeding and when I stopped eating for 2 weeks, due to pain from a undiagnosed gluten sensitivity. Anyway, I eat around 900 cal/day and still cannot lose weight. Even if I sleep all day, wouldn’t 900 calories be enough of a deficit to lose weight?? I do lose weight and become more insulin sensitive when fasting 18 hours but as soon as I eat the weight comes right back. I think it is WAY more difficult for me than other people with or without diabetes.
Also, I drop 30-40 mg/dl when walking 30 min. Are you saying that my basal is too high, if I can’t exercise without a drop in BG? A well known author and blogger with diabetes also recommends walking to reduce BG in T1D’s immediately following meals. Are you saying that is incorrect and that it only has to do with basal? Should I be able to do any activity without decreasing my BG?
Also, I would love your take on all those changes in basal requirements, like hormones etc.
Thank you and I appreciate all of your helpful information!
Christel Oerum
Hi Krissy – glad you like the site!
My guess is that your body is in complete starvation mode and unless you slowly increase your calorie this weight management will only become harder for you going forward. I’d suggest what we call reverse-dieting, slowly adding back more calories to not gain a lot of fat. And then you can start leaning out again. Might take some time to fix.
As for the basal question. Yes, if you’re fasting and walking makes you drop (and you don’t want it to) your basal needs to be reduced. That being said if you’re running high or have your AM hormones pushing your BG up, walking could be a great way to get it down.
As for basal requirements throughout your cycle you might need more insulin mid-cycle and end-cycle simply because your estrogen levels are higher at that time which makes you more insulin resistant
Ginger Vieira
Hi Krissy!
In addition to all of Christel’s great responses above, I just wanted to offer a couple things to keep in mind:
1. There are A LOT ways I could try to lose weight that wouldn’t work well for me. But there are a couple that I know do work for me. My point is that what you’ve done in the past clearly hasn’t work for you …so what have you NOT tried? We tend to go back to our same ideas and efforts even when they don’t work if that’s the best idea we have for the issue. Working with someone like Christel and really getting your metabolism and nutrition finely tuned by someone with an outside perspective and some new ideas for you might be really, really worth it!
2. Like Christel said, your body wasn’t losing weight on 900/calories a day because that is WAY too low. When we deprive our bodies that severely of calories, they go into “starvation mode” and cling to every ounce of fat on the body, and absorb every calorie you eat. Fueling your metabolism to WANT to burn off extra fat is a bit of an art — and it’s something Christel excels at teaching people. But most of all it shouldn’t involve eating below 1200 calories at a MINIMUM.
3. Yes, your basal rates are definitely too high if walking on an empty stomach first thing in the morning drops your BG by 50 pounds. BUT if you’re talking about walking after lunch and after taking some insulin for a meal, then no, it makes sense that your BG is dropping. Highly recommend the book “Diabetes Athlete” by Sheri Colberg for better learning how to balance your BG around exercise OR working with Christel!
So again, I just want to ask: what have you NOT tried yet?
And what have you already tried that you know does NOT work for you?
Kristin
Curious. I’ve been “skipping” breakfast here and there for a while. It helps me enjoy meals with my family more, but I was worried it was bad for me (Breakfast is the most important meal of the day!) Hoping to learn more about intermittent fasting as a type 1 diabetic for weight loss. THANK YOU for the great article!
If I drink water and green tea with stevia throughout the morning, does that count as fasting? Does the artificial sweetner affect the fast? What about a coke zero?
Also inquisitive about medication…like thyroid pill first thing in the morning with water?
Probably will be dependent on individual, but I was just curious if you have any insight or can direct me to more information. Thank you.
Christel Oerum
Hi Kristin,
Good questions and glad you found Ginger’s article helpful. Water, tea and coffee (or coke zero) won’t break your fast.
Skipping breakfast is only really bad if it leads you to make less optimal food choices the rest of the day.
Wanda
I really want to say thank you so much. I
Have been doing keto for quite a while. And have fasted a few times. I haven’t been sure about it being safe with me being TD1. Thank you sooo much. The freedom is great. I do not like the one meal a day fasting. Honestly I’m not hungry so that is easy to do but getting my veggies in is important to me.
Ginger Vieira
Wanda! Thank you for reading, and for your comment. I didn’t used to like the one meal a day fasting — it felt like a struggle to wait that long to eat…and then I did it several times by accident because of crazy days with 2 little kids…and I kind of like it now. Good thing there are a variety of approaches we can choose from!
Helle Nyrup
I like to do an hour of a spinning class in the morning without eating breakfast, but I have to eat aprox. 8 glucose tablets during the class. I only take 8 units of basal before nighttime. Would you say that when I know that I’ll do a morning spinning class, I should lover my basal to eg. 4 units.
My question is then: What about the rest of the day? If I eat normally, will I not be in need of my basal then?
Another question: I thought that muscles needed the glucose in order to do a good exercise – isn’t that so?
Ginger Vieira
Hi Helle!
1. Your body is VERY capable of producing glucose fuel without eating carbs — by turning protein in glucose. But the entire point of ketogenic and low-carb dieting (and the same logic applies to fasting) is that your body is burning body fat for fuel instead of just the food you eat. If your body required food every time you exercise, that would mean your body never burns fat during exercise…which we already know isn’t true. By fasting before you exercise, you’re helping to ensure that your body is burning fat for fuel instead of the glucose in your bloodstream! THat’s why it’s so great.
2. Regarding your blood sugar dropping during your spinning class. Let me start by stating: I am not your CDE. 🙂 Now that that is out of the way….if I were you…it sounds like you’re actually taking too much basal. You really shouldn’t need to feed morning cardio if you wake up with an in-range blood sugar and you aren’t taking any injections of fast-acting insulin. Again, if I were you…I would try reducing my basal dose by 2 units…and then see what happens. (I say two units because in generally it’s really advised to only make adjustments in insulin doses by 1-3 units maximum…since you are clearly very sensitive to insulin, 2 would be your maximum.) Let me know how this sounds to you. If you’re worried about going low, even after making a decrease, you could have a few glucose tabs…and if you’re high during/after your spin-class, then you know you can probably skip the glucose next time.
I’ll check back to see any replies you leave so please holler back with questions and results!
Kim
You never spoke about exercising in the am during your fast?
What’s the best way for a type 1 to do this without having crashing blood sugars?
I’m very interested in IF as a type 1 I never knew how to do it safely
Once you outline how to exercise on IF I’ll be good to go!
Ginger Vieira
Kim! How incredibly silly of me…you’re right, this should absolutely be addressed! We added a section specifically about morning exercise. SPOILER ALERT: it’s actually EASIER to exercise while fasting! I do it as often as my schedule allows!
Karen
I have always done my morning workouts fasted (no food), regardless if a long run or a heavy weight training day as I am an “early bird.” However, I do drink a glass of water & I need my 2 cups of black coffee before I embrace my day. Does the body consider this coffee as caloric ? … and switch to glucose burning or am I safe to keep the coffee and be in a fat-burning state?
Ginger Vieira
Hi Karen!
Black coffee is definitely OKAY during fasting! I drink black coffee every morning as part of my fasting routine. If someone (you or someone reading) notices a spike just from drinking black coffee, there are some people whose bodies react pretty strongly to caffeine. Gary Scheiner offers a great explanation of how caffeine can sometimes cause blood sugar spikes….but again, this does not interfere with your fasting goals: https://www.diabetesdaily.com/blog/2014/01/does-caffeine-raise-your-blood-sugar/
Meg
This was such a great read. I am a low carb eater but not keto. I exercise about an hour after waking up but eat twenty carbs first thing (taking insulin for it) with one cup of black coffee. I always ALWAYS spike heavily during my workouts, even when bolusing beforehand, running increased temp basals during the workout, and checking midway through and often bolusing again. (I know it’s the workout doing this and not my breakfast carb ratio because on the mornings I don’t workout and just eat my twenty carbs + black coffee I stay very flat on my CGM). Do you think IF would lessen the workout spike? It drives me crazy that my workout is the highest part of my day! I am fine with taking some insulin to workout but it would be nice if IF could help me blunt some of the high blood sugar I get during the workout. I appreciate any feedback you have!
Ginger Vieira
Hi Meg!
I would definitely try your first IF workout with ZERO food and zero bolused insulin.
Test half-way through and again at the end and see if you still spike.
Then, if you do spike (which I suspect you will), you would simply do what I have to do if I were to weight-lift first thing in the morning on an empty stomach: take a little bit of insulin right at the start of that workout. For me, this amount was 1 unit. That 1 unit kept my BG well below 150 mg/dL during my workout. Without it, I would rise up to 250 mg/dL and beyond!
Test during your first workout with that extra bolus, too, of course. To see what happens.