Intermittent fasting with type 1, safety and muscle build concerns

Hi all,

So this is not quick and I’d better give a background rundown, before I pose my questions. I’m 36, male, living with T1 for 11 years now. 6 years ago I read ‘The Primal Blueprint’, by Mark Sisson and took a turn away from anti-depressants, a work burnout and insidious weight gain. I’ve tried to stick to a paleo diet and have succeeded sometimes for months at a time, but never truly long-lasting. I measured my success by average blood glucose and amount of carbs/day. My HbA1C is around 6.5-7.5%.

Fast-forward early this year - I read Dr. Bernstein’s book and reinforced my health habits of a LCHF diet. I am currently practicing an intensive sports regiment: biking to work, total of 25 km a day, swimming once a week and then going to gym, bodybuilding and strength training 7 times a week. My body is really strong and sculpted.
Or wait, it’s actually not. Indeed my arms, shoulders, chest, legs, even butt are sculpted, but the trunk… The trunk is a fat mess, looking more like a sedentary weakly 45-year office worker, than a guy who can dead-lift 180 kg (400 pounds).
Body fat percentage says 24% (although I am not concerned with that number) and I can feel a six pack under the round mess I got for a mid-section.

I believe now that my T1 is also partially a T2, that insulin is making me fatter and that I am becoming insulin resistant. Last week I bought ‘The complete guide to fasting’, by Jason Fung and Jimmy Moore, and you won’t believe how excited I got (well, you would believe, if I told you I read the book in a day). I’ve been intermittently fasting now for a second day, having bulletproof coffee in the morning and then one meal in the late evening. It’s not easy, but my insulin requirements are basically only basal, and even those have been only 2/3 from normal. I think this is all great! I don’t know whether I can keep it, but I love it.

I do, however, have concerns of the safety of an IF protocol for type 1 people. For example yesterday I got a low during the day that lasted 3 hours – I noticed it at 3.3 (60 mg/dl) and immediately suspended my pump. During the next hours it reaaaly slowly rebounded to 5.5 (100) after having first dropped even lower. During this time, without eating, I could basically focus only on reading, i.e. I couldn’t drive (to shop as planned) or engage in a conversation. This concerns me as I am biking 13 km trips and here’s the deal with IF – the body supposedly first depletes the liver of glycogen stores, before it can get into a ketogenic state and start burning fat for fuel. What I am afraid of, is that the liver may not have enough sugar to counter a low, and thus in a biking session, get into a too-dangerous low (I’ve seen a fare share of biking-induced lows, especially when having a big meal for lunch and insulin finally kicking in 5 hours later on the way back home).

Another concern is, if I’d really get to keep my muscle. In the fasting book it’s mentioned, that thanks mostly to Human Growth Hormone, muscle mass is almost entirely preserved during extended fasts, but perhaps it probably is assuming overweight/not muscular body types and perhaps not the types that are actively building muscle mass. Also, so far I’ve tried intermittent fasting, not full-blown ones, and there’s no mention of IF/muscle mass relation.

What are your experiences with IF or longer fasts? Do you have any advice that I can apply to my regimen? I appreciate any advice :slight_smile: Thanks!

For starters, if your A1c is around 6.5 to 7.5, I’d say you need more insulin.

There is no such thing as “Type 1 that is also partially Type 2.” You may have insulin resistance with Type 1, but there is no such thing as “double diabetes”.

And I’d never sit on a low that affected cognition without treating it for hours while waiting for it to come up on its own…

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Good points.

Whenever my A1c is lower than 6.5, it has always come with much more hypos than usual.
Also insulin is typically not working fast enough, as I mentioned the bike example - BG stays very high in the office for hours on end till I start biking when it finally drops to a big low. More insulin may just not be what I need, but rather more insulin sensitivity.

The double diabetes wording may just be a technicality. What I meant is, of course, insulin resistance (which IMO is not talked about enough when discussing type 1).

Also, on your cognition pointer, I’d say it was borderline affecting, and I was checking every 10 minutes, that it doesn’t drop below a threshold. I wouldn’t drive with semi-low, just for the reason that it may go lower during the drive.

As a parent of a type 1, I suppose it’s harder to discuss actual IF attempts at curing things related to hormonal imbalances, as I assume your child is still growing.

Thanks anyway!

Insulin does not take 5 hours to begin working. The DIA may be as long as five or 6 hours for some people, but its onset of action is no where near 5 hours. You should read Think Like a Pancreas by Gary Scheiner.

I believe that I have a chance at reducing the damage I get from diabetes. And that more insulin is not the answer. I have mentioned already a few times in this thread the phrase ‘insulin resistance’ and that is what I am focusing on with the diet as well.
And once again we talk technicalities, it requires a lot of conversation time to be medically-precise. Such as, yes, insulin will start working much sooner than the 5 hours, but for a very low carb diet, the BG levels while mostly sedentary rise unacceptably high. And yes, I can guarantee, that I can experience a drop of 140 mg/dl many hours (5!) after bolusing, when biking or swimming.
About the book - I’ve had it for a few years (and yes, have read it), but thanks for the pointer regardless.

What you are describing appears to be a matter of a too-low basal rate if your BG is rising with no carbs on board (without exercise).

I don’t think so. I could leave my basal rates here, reviewed as well twice a year by my doctor, but it feels off-topic.
I’d rather hear from people with experiences or situation similar to mine.

By definition, if your BG is rising many hours after eating, your basal rate is too low. And if your endo is comfortable with you having an A1c over 6.9, I’d be looking for a new endo. If the only way you can achieve a 6.5 is by experiencing a lot of lows, you clearly need to adjust your pump settings.

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So, I think you might be a bit confused about what (in a diet) is responsible for what. I was initially diagnosed as Type 2, and started LCHF and also IF on the suggestion of my younger brother (Type 1). Now looks like I’m actually LADA, but I’m not yet on insulin therapy, so I can’t speak to that. But I can speak to the idea of “being in a ketogenic state and burning fat for fuel.” There are common misconceptions about this that abound online:

  1. Calorie consumption and TDEE determine weight gain or loss. If you eat more than your TDEE (Total Daily Energy Expenditure) you’ll gain weight; if you eat less than TDEE, you’ll lose weight.

  2. Whether you burn fat or muscle primarily depends on a couple of factors: if you’re in a very, very deep calorie deficit (experts suggest never going below 1,200 kcal per day for most men), your body can go into a starvation panic where it attempts to hold on to fat stores at the expense of muscle and bone; if you don’t eat enough protein, your body can enter a catabolic state where it burns muscle protein for energy (usually eating ~0.6g of protein per lb of lean body mass is enough to forestall this).

  3. “Nutritional ketosis” is real, but it’s not nearly as complicated as people make it seem, and it’s not really related to weight loss. It can help with fat loss, but it’s more a side effect of getting calories right. The largest benefits are to carb-restricted endurance athletes, who want to fuel long-term energy expenditure without relying on high-carb glycogen fueling (carb-loading). It is also useful, obviously, for diabetics who want to reduce daily insulin needs (primary for Type 2, also useful for some Type 1).

  4. Intermittent Fasting hasn’t really been shown, scientifically, to have any great benefit to being in ketosis or losing weight, except for that it makes eating at a deficit easier for some people. This is pretty simple: if you restrict your eating to a small window of the day, you literally learn to “deal” with feelings of hunger; if you’re also disciplined about how much you eat during your window, it becomes easier to deal with a calorie deficit.

  5. Similarly, eating protein and fats leads to feelings of satiety (this is hormonal in nature) faster than eating a similar total calorie load of carbohydrates: LCHF (or low-carb, high protein) diets aren’t really magic weight-loss diets, but they do help many people to feel fuller while eating at a deficit and eliminating most carbs from the diet. You just feel full faster eating large amounts of (particularly) protein as a proportion of your meal, and it makes it easier to eat less.

  6. Combine LCHF and IF, and you have a pretty solid basis for supporting the behavior of eating less calories through the day while attempting to lose weight. Again, it’s not really biochemical or magic in nature (as far as we really know), other than reducing the amount of insulin a non-Type 1 diabetic produces during the day. It is my (temporary) treatment method for that reason: I have endogenous insulin production, and LCHF (and some IF) helps me to keep my carb intake in the range my insulin production can handle. For insulin-dependent diabetics that eat this way, it reduces total daily insulin usage.

Ok, so that’s a lot of text, based on my own research, my PhD in biology (and reading a lot of scientific texts, although I’m not a dietitian or even human biochemist), and my own experience. I also exercise like crazy as part of my treatment plan, and I have some additional experience with eating low-carb while exercising:

  • I’m not insulin dependent, and I can experience real, actual, physiological hypoglycemic episodes during the day (never at night) if I exercise while fasted. I usually wake up in the 75-95 mg/dL range, but biking (or even strength training with no food intake) can take me down to the 50 mg/dL range within about one hour. Although I produce little insulin, I also have very little stored glycogen because of eating low-carb consistently for months. This means that I can deplete glycogen stores and my small amount of circulating (endogenous) insulin is enough to bring me low(ish). Not passing out and in immediate danger of dying low, but low nonetheless. I adjust to this when biking or running by using something like Clif gels (1/2 dextrose, half starch) in order to help me not dip below 60 mg/dL or recover to the 90 mg/dL range, but I figured it out over time. If I were on insulin, it’d be a challenge to figure out the break points for eating carbs and cutting back basal in order not to go low.

  • Exercising and getting enough protein in the diet is really important if you want to lose body fat and maintain/build muscle. Sounds to me like you are generally doing this, but you might not be eating at an actual deficit (you mentioned creeping weight gain), and if you follow a typical LCHF diet, you may not be eating enough protein to maintain muscle. If you get your macros and calorie consumption right, you can absolutely lose some of that core fat, but it takes a lot of time if you don’t want to lose muscle mass.

  • No way to sugar-coat it: what you’re describing as a goal (body sculpting, losing that core fat while maintaining strength elsewhere) is body-recomposition. That is a much longer process than losing weight, and there is good experience online on how to do it (it is, after all, what all bodybuilders do, just most do it with higher-carb diets). A good resource for eating low-carb and working on body recomp is available at I myself use the macro calculator there to help hit my goals (I eat at maintenance calories with a lot of protein because I do a lot of strength training and don’t want to lose weight or fat, myself).

So, here’s the tl;dr: My actual experience with IF is pretty simple. I practice a really lazy sort of IF as a way to make sure I’m not under or over-eating (fewer meals per day means fewer calculations of calories, carbs, etc.). I usually don’t eat until lunchtime (sometimes I have buttered coffee in the morning, but never carbs), and then have lunch, mid-afternoon snack, and supper in a 8 hour window (noon-8:00pm). I eat less than 30g of net carbs per day, usually 45-50g of gross carbs per day. I spread those out between my three “meals,” usually not eating more than 20g gross carbs for lunch or dinner during my 8 hour eating window. My maintenance calorie needs are between 2,100 and 3,000 calories per day depending on what kind of exercise I’m doing. I get my calories from this distribution, on average: 7% carbs, 35% protein, and 58% fats.

It works great for eating at a deficit or maintenance and making sure that I don’t gain bodyfat (I’m about ~16% at 41 years of age and am happy with my body comp at the moment) and core fat. It makes balancing BG easier in some ways (much easier to keep postprandial BG flat in the evenings by not eating carbs in quantity), and harder in other ways (I have to eat carbs during endurance training). When I start insulin therapy, I’ll defiitely want to re-evaluate my eating habits. I do know Type 1s who are insulin-dependent who eat LC and are athletes, so I know it can be done with experimenting. And they tend to do well in terms of BG control.

If you read this far in this massive wall of text…congratulations! Your patience is exemplary. I’m just rambling since I’m up with baby and don’t have any pressing work to do for another hour or so :slight_smile:

If you want to read about the experiences of some actual experts (medical experts) on eating low-carb and exercise for both body recomposition and endurance training, it’s worth reading around in Dr. Peter Attia’s website: He delves deeply into the science, got interested in low-carb because of similar concerns as you (he was a competitive athlete but had far too much core fat and was diagnosed Pre-D), and now eats more moderate-carb high protein after changing his body type. He’s also, now, a metabolic specialist and really understands the concerns around diabetics of all types, metabolic syndrome, etc. and how to successfully eat lower-carb while exercising. Worth checking out.

This isn’t about IF, but have you considered trying metformin (I recommend the ER formulation), if you think you have insulin resistance? More and more Type 1s are doing that (obviously in addition to their insulin), including myself. It has helped me lower my A1c/stabilize blood sugars tremendously, without any problematic side effects, and it helped with weight loss.

It’s fine to be concerned about body shape, but it’s imperative to be concerned about health. An A1c of 7.5% is not conducive to health and freedom from complications, long term. Period. Full stop.

If your fasting BG is unacceptably high, it means that your liver is overproducing or your pancreas is underproducing or you have some degree of IR. Or, quite commonly, some combination of the three. If the deviation is mild enough, metformin may fix it. Otherwise, basal insulin is the answer. If it isn’t working, it’s not enough. Period. Full stop.

If you have an ample supply of body fat (and at 24% there should be more than enough), a ketogenic state should be burning fat, not muscle. In fact, that’s what the word ketogenic means: fat-burning.

Also, when interpreting your numbers, bear in mind that exercise temporarily lowers IR, sometimes dramatically.

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@thracion, I too practice IF with great results. I think its a great tool in our D toolbox. However, mine is not as extreme as yours. My routine is to fast in the morning and only drink black coffee up until late lunch. Breakfast is not needed (for adults) to the dismay of many. The mornings is also the time I do my Pod changes. Doing an infusion change when you don’t need to bolus is great at keeping the BG’s flat. Then by the time lunch arrives the new pod/infusion is ready and more reliable in my opinion.

Since I started this my A1c has dropped from 6.8 to 6.2 (Clarity now says 5.8). And my bodyfat% is around 9% (hydrostatic tested).

To address your concern, if you eat the minimum amount of calories needed for your body build, then you will not lose muscle mass. You will only lose fat. But you have to take in enough calories in the small eating window you have created.

Thanks for all the advice. I’ve been away for a few days and too busy to plan a proper reply.
My test continues as planned, mostly fasting during the day and then having a light-caloric meal during the evening. Sometimes I have lunch.

My latest A1c has been 6.8%, but that includes a very stressful period in my life and I’d guess w/o it it would have been a few points lower. Average BG measurement for that A1c are somewhere between 9 and 9.5 (x18). Current BG with fasting is 6.1 average with no big highs as well, so I am expecting my February test to show a lot lower A1c as well. That is assuming I can keep up with this awesome numbers.

IF has been actually fun, my keto-numbers have been varying between 0.4 and 1.2. and I’ve felt much more focus and energy. Also the brain fogs I experience typically after large-ish meal, the glucose spikes, the inability to work for hours even with a very low carb salad (even with carbs coming from veggies only) are now gone. I find also that my control muscle is much better, I haven’t been indulging as much in other forms of fun as well, like digital entertainment or games, and instead have been focusing on reading actual paper books.

My muscles (for example arms) seem to be a bit shrunk, but I think that’s part of the weight water loss. Anyway strength-wise in gym I don’t seem to have lost any edge.

I would personally stay away from the advice of getting extra medications. Part of the reason I am doing this is to be less dependent on medication in first place. My insulin requirements have dropped significantly even on non-fasting days and I think that’s a great improvement. Average have been 53 units of insulin, while current 6-day average is 34.

Actually I read about one idea, that I’d like to share, as I am currently trying it out:
The idea is simple - your liver is running out of glucose on a fasting day and as the levels deplete, on the following non-fasting day, any amount of free blood glucose will be more likely to be used by the liver to refill the emptied glycogen stores. So essentially a 1:1 diet can have near double beneficial effect for diabetics by keeping the off-days BG lower than average as well.

A great tip: I made a giant pot of bone broth (10l), which has really helped during the IF. Probably this is the first 22-24 hour fasting I’ve experienced since well, ever and as the Complete Guide to Fasting book said, the first couple of days are always the hardest, but as you do it more and more often, expect even that to get easier. Having a warm cup of broth definitely helps!

Thanks again for the awesome advice!

I’m T2 and guessing…

It sounds like you have swapped over to burning fats, I think is why you feel ok now. Ketogenic state.

before you do anything else google lipohypertrophy’ it may or not apply, but will explain stuff. :slight_smile:

I too have a Fung’s book, Obesity code… I.F. for a T1? I think there is a lot of basic stuff to get right first and then add I.F, if needed. I don’t really have an issue with a bulletproof coffee, 2 tablespoons/200 cal? and having one decent LC meal of an evening, 2 or 3 days a week, if your bloods are good to start with. without this and burnstein or LCHF keto, there is no reason you can’t get low A1c 6’s or well onto the 5’s

I wouldn’t suggest IF as first line BG control. I would suggest you continue with a LCHF ketogenic. read or youtube anything from Volek, Phinney, Westman et al

I’d back off hard workouts for a week, because as you know, that adds another level. and I’d get your lounge lizard basal dose worked out first.
overnight and miss ‘one’ meal during the day. quck carbs and fats with the previous meal, go easy on the protein, that may be worked out and a seperate part bolus later, and high protein will mess up the basal test (3-6 hour digestion)

you may need to split, part bolus for up to 50% of your protein grams.
TAG ‘total available glucose’

join FB group,T1grit this is the public page

Like T2’s the liver glucagon isn’t turned down when you have a meal/insulin with t1. It’s pumping away all day and night… @rgcainmd, I think you would get something from this vid too.

Thank you for the awesome links as well, @jack16 and @David49 !
I’ll go through each one in detail.

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Any progress on the trunk fat?