Increasing Fat is not going to help you in HIIT. At higher intensity your body needs energy fast, which fats can't provide. HIIT+Low carb is not something you would want to do. The muscles will start using lactic acid ATP for fuel and it often means Hydrogen in your muscles. Choose between carbs or not doing HIIT. If you do try, post your experience.

I've also read in many places that HIIT is ideal for keto. I suggest you read any research you can find, OP, just for your own peace of mind. I'm sure not many of us are physicians or researchers, so it's best for you to give yourself as much education as you can before making these decisions.

I did find the following info online, however:
http://www.ketogenic-diet-resource.com/high-intensity-interval-training.html

If you work your muscles at enough of an intensity for at least 90 seconds before they fail, all three types of muscle fibers will be called upon to do the work. Once all of these muscle fibers are called on to work, it causes a chemical cascade in the muscle which dumps the stored sugar/glycogen, which in turn increases not only the muscle's size and strength, but also its insulin sensitivity and fat burning potential.



At that point, the causes of why we get fat are being reversed, glycogen tanks are less full, muscle cells become very sensitive to insulin, insulin levels drop, and fat is released from the fat cells so it can burned for fuel. Now the process of good health and weight is going in the right direction.

As for the question on the breakdown of the calories you will eat after workouts, I'd honestly suggest sticking to your original macro goals, percentage-wise. Eat as you would normally. If I'm not mistaken, which I very well may be, I think MFP increases your daily goals according to your set standards after exercise.

Finally found this on YouTube. Couldn't find on Dr Attia's blog. This talks about metabolism in ketosis.

http://m.youtube.com/watch?v=NqwvcrA7oe8

I am on my phone, if link doesn't work just search Dr. Attia on YouTube.

Call a university near you, they will most likely help you get tested.

HIT isn't the exercise for a low carb diet. You want sustained effort rather than bursts. Walking, especially hiking/bushwalking is perfect especially if there are some steep climbs and rock scrambling. Weight and resistance training are also good.

You just don't need to stress yourself out with red faced cardio bursts like carb eaters. You won't win any sprints on keto but you will finish the marathon with energy to spare.

Increasing Fat is not going to help you in HIIT. At higher intensity your body needs energy fast, which fats can't provide. HIIT+Low carb is not something you would want to do. The muscles will start using lactic acid ATP for fuel and it often means Hydrogen in your muscles. Choose between carbs or not doing HIIT. If you do try, post your experience.

Wait, wut. Can you provide sources for that, Fattyman? Because everything I've ever found states quite the opposite.

Carnivor0us has it right that a small amount of carbs a half hour to hour beforehand helps sprinting ability and "burst mode" fast twitch muscle fiber, but anyone absolutely CAN do HIIT and tabatas and stuff in ketosis. Take a couple spoonfuls of unrefined virgin coconut oil before you hit the gym, it's a quick-releasing energy source that your body can use very efficiently for sustained periods.

Yes, generally, carbs are meant for vigorous workouts (sprints, heavy lifts) while fats are recommended for sustained low-intensity labor (marathons, swimming), and I understand where Fattyman is coming from regarding the carby anaerobic ATP production versus the fatty aerobic ATP cycle, but if you are fully fat-adapted, your body actually becomes really good at continuing the Krebs Cycle (anaerobic ATP production) using molecules gained from tearing apart body fat as a substrate instead of using glucose.

It's pretty much the entire point of the keto diet, to be honest. It's why we have steady levels of blood sugar even if we haven't eaten anything in 3 days and only had a couple pounds of rare veal during the week before that. Humans evolved to produce and thrive off of ketone bodies in the absence of glucose.

I would bet that many people (possibly including me) think they are doing HIIT but aren't high intensity enough. So we could still be burning some fat in addition to glycogen.

Fattyman007 - you don't change your macros when you do sprints/anaerobic, yet isn't this what you suggest others not to do?

Also, I haven't researched this but MCT such as coconut oil are metabolized differently than other FFA. I wonder if they are used instead of glycogen once you cross over your AT.

I find my exercise suffers if i 'carb up' prior to it. It only took a few weeks to be able to keep up in my HIIT but thats normal when switching to low carb/keto anyway. I find i exercise better on keto then i ever have prior to it (my blood sugars where fairly unstable befor ei started keto even with taking 1500mg of metformin, which i have no reduced to 500mg with drs approval).

Do whats better for you, I find this better for me.

Increasing Fat is not going to help you in HIIT. At higher intensity your body needs energy fast, which fats can't provide. HIIT+Low carb is not something you would want to do. The muscles will start using lactic acid ATP for fuel and it often means Hydrogen in your muscles. Choose between carbs or not doing HIIT. If you do try, post your experience.

Wait, wut. Can you provide sources for that, Fattyman? Because everything I've ever found states quite the opposite.

Carnivor0us has it right that a small amount of carbs a half hour to hour beforehand helps sprinting ability and "burst mode" fast twitch muscle fiber, but anyone absolutely CAN do HIIT and tabatas and stuff in ketosis. Take a couple spoonfuls of unrefined virgin coconut oil before you hit the gym, it's a quick-releasing energy source that your body can use very efficiently for sustained periods.

Yes, generally, carbs are meant for vigorous workouts (sprints, heavy lifts) while fats are recommended for sustained low-intensity labor (marathons, swimming), and I understand where Fattyman is coming from regarding the carby anaerobic ATP production versus the fatty aerobic ATP cycle, but if you are fully fat-adapted, your body actually becomes really good at continuing the Krebs Cycle (anaerobic ATP production) using molecules gained from tearing apart body fat as a substrate instead of using glucose.

It's pretty much the entire point of the keto diet, to be honest. It's why we have steady levels of blood sugar even if we haven't eaten anything in 3 days and only had a couple pounds of rare veal during the week before that. Humans evolved to produce and thrive off of ketone bodies in the absence of glucose.

Watch this video on metabolism in Ketosis including exercise of different intensity. If you are in a hurry watch it after 21 min mark.
http://www.youtube.com/watch?v=NqwvcrA7oe8
Read the book of Volek on performance.
Can you do HIIT on Keto?
Sure, You will be getting fuel from carbs not fats once you hit Anerobic Threshold. By product of this is Hydrogen, will you fall off? Absolutely No. You can definitely push through the work out. But is it worth risking a long term injury or muscle stiffness? You decide.
Personally I don't want hydrogen in my bones.
When you are fat adapted, you are not going to suddenly burn fat at higher intensities. You might be able to increase the AT to 75% VO2max but its usually harder for even elite athletes.

Like I said, go do a RMR, VO2/VCo2 test, it will tell you what you are burning for fuel, carbs fats etc at various levels of intensity. Its usually done by putting a mask and measuring Oxygen and CO2. I rather burn 600 cals/ hr at 95% fat than 900 cals and 95% glycogen.

I would love to see the data of fats/glycogen burned by people who say they are doing HIIT. Even the fittest of guys I have seen at the university in Ketosis usually don't burn more fat after they cross 162 HR. Like I said, you can do HIIT but you are burning carbs and end up with Lactic acid by products in bones.

Hello, I would like to share my experience in regards to this topic..

I have been doing Circuit Trainings (Jillian Michaels'- which go upto 55-60mins) and then 30mins of cross-country training program on Elliptical. I use FTR4 to track my HR and calories burnt. When i started Keto (actually inspired by atkins first) i weighed 95kgs (~209lbs) and in around 3weeks (doing keto at 21g net carb intake and the aforementioned trainings) i weigh down to 88kgs (~194)

I would feel dizzy (little) and tired after my workout. Completing my 90mins training at gym would take real efforts (maintaining my HR between 155 and 175). Since Monday i started taking a pre-workout drink (greek yougurt+almond milk+dried cranberries+dried raisins+banana) 30-60mins before my workout. After trying this for 3days, I didn't feel dizzy and my workouts would get completed easily. Plus, I would still feel active (instead tired) at the end of workout.

I find it helpful to have a pre-workout good carb drink so that I can use it for my workout and not affect my overall net carb intake. However, mfp does not sees it this way. It counts the carb intake of my pre-workout drink but my friend asked me not to count pre-workout carb drink as those will get consumed during my workout.


Your suggestions/comments are welcome to let me know if I'm on right track or doing something wrong.

You would need to add it as part of the diary. Adding carbs is a good way to get through high intensity exercises, but you might not be in ketosis. If you don't care about ketosis, this is a great approach. Another drink I use with out getting kicked out opt ketosis is Generation UCAN super starch. I use them only for work outs longer than 90 min though.

I do HIIT style exercises once or twice a week with with a personal trainer and it's pretty much a non-issue for me. I eat my regular keto diet, when I need more calories for any of my exercise, I eat more fat, as usual. I actually last through these exercises better than my husband, who is on a regular high carb diet. I've been on keto since July 2013 and exercising with my trainer since December 2012. I also do long running (half marathons) and Hot Yoga.

I think the thing you have do is always a N=1 test - just try it, and see how it goes for you. Everyone's body chemistry is different and you just won't know how you'll do until you try it.

One or two a week is ok, I do my interval sprints once a week with out carb loading. I have seen people trying to do insanity and HIIT every day, which is not a great thing to do on a low carb diet.

@Leonidas : I do HIITs thrice a week and cardio five times a week. When I am adding the pre-workout drink (rich with good carbs) and then my calories burnt, mfp adjusts and shows my total net carb. Would you have any other alternate natural source of drink/food that will help with getting through HIITs? I had tried atkins' chocolate drink shake as pre-workout drink (net carbs= 3g) but then that wouldn't let me through my HIITs

@Leonidas : I do HIITs thrice a week and cardio five times a week. When I am adding the pre-workout drink (rich with good carbs) and then my calories burnt, mfp adjusts and shows my total net carb. Would you have any other alternate natural source of drink/food that will help with getting through HIITs? I had tried atkins' chocolate drink shake as pre-workout drink (net carbs= 3g) but then that wouldn't let me through my HIITs

That is a good approach to include carbs if you are going to push 85-95% of max intensity. Depends on what level of Vo2max or HR your HIIT and cardio is at. I do cardio 4 or 5 days a week with one HIIT and have no problem with the Glycogen available in the muscles for me to get through the workouts.The only drink I use for carbs is Generation UCAN super starch on my sunday long runs, which are usually 2-3 hrs. You can experiment to see how each approach feels and also check for ketosis. If more than 3 HIIT needs to be part of your routine, try a Cyclic Ketogenic Diet.

That is a good approach to include carbs if you are going to push 85-95% of max intensity. Depends on what level of Vo2max or HR your HIIT and cardio is at. I do cardio 4 or 5 days a week with one HIIT and have no problem with the Glycogen available in the muscles for me to get through the workouts.The only drink I use for carbs is Generation UCAN super starch on my sunday long runs, which are usually 2-3 hrs. You can experiment to see how each approach feels and also check for ketosis. If more than 3 HIIT needs to be part of your routine, try a Cyclic Ketogenic Diet.

Other people may be different - but for me, I *need* a good intake of carbohydrate roughly 90 minutes before my HIIT, or I can't usually push above 85% of my max HR. Personally, when I do my HIIT I like to push to 95% - 100% of my max HR (which for me means getting to minimum 190bpm as my maximum is just above 200bpm - I'm weird) ... Usually I do about 20 minutes HIIT, and sometimes 30 minutes, which is absolutely draining at the level I push. I typically eat up to 55g of carbohydrate before those long HIIT sessions, and I might eat 80g-100g total that day.

Days I'm NOT doing HIIT I'm typically under 60g.

I like the lemonade one better, taste is something you need to get used at the beginning. But, it's great for endurance activities. I ran a half marathon with Generation UCAN 30 min before the race. I had nothing but water during the race. I finished 3rd and was laughing inside as I passed people who were stuffing gels and drinking Gatorade to refuel.

It's amazing the number of people that "poo poo" the low-carb lifestyle for endurance.

I haven't tried the Generation UCAN products yet - and I don't run half marathons (it'd kill my spine) but I *DO* engage in endurance cycling.

People are often stunned when a guy my age and my size just keeps on going at average 30+ km/h during a 5 hour ride into and back out-of the mountains without carb-loading prior to the event, and then during the ride being the only guy NOT constantly sucking back gels, bars, etc., etc.

What I do instead is eat a breakfast that includes around 45-50g of carbohydrate (usually around 800 calories total, I'll include some berries and whipped cream on ONE oatmeal pancake), then I start the ride and eat a PB&J sammich halfway, made from sprouted-grain bread (very slow digesting) with a huge amount (easily 4-5 tbsp) of natural peanut-butter and a little no-sugar added jam.

Other than my water/powerade zero mix (for 5 hours you need the electrolytes) there's no ingesting anything else during the ride. Other guys are slowing to pull bananas, bars, gels, all kinds of things out of their jersey's and eat them, and I just keep going.

I've been doing Tabata style HIIT workouts for a few years now. Started keto a little over a month ago. The workouts were tougher than normal the first few days, but no real problem after that.
I usually do these workouts 5 days a week for 60 minute sessions, although with the warm up and cool down, the HIIT part is probably closer to 45 minutes. No problem at all under 20g Carbs a day. Heck, no problem at all even on a fat fast (1000 cal a day; 90% fat). It's just about retraining your body to use fat for fuel. There's no need to add calories or carbs when you're working out if you're keto-adapted and looking to lose weight.

No offense, but I'm not sure you're actually familiar with a Tabata protocol. A true Tabata style protocol is next-to-impossible to carry out to 45 minutes unless you're superhuman - as the protocol is designed for 170% of VO2 max for 20 seconds with 10 seconds of rest in-between. And it was meant for a whopping 8 repeats.

Most people that SAY they do HIIT claim to do intervals where they push to 90 or even 95% of their maximum heart rate ... But herein lies the question ...

Are you actually going to 95% + of your TRUE maximum heart rate, or your PREDICTED (using a formula) maximum heart rate?

FYI ... the formulas are a prediction for the average person, and aren't remotely accurate for many of us. Some athletes have true maximum heart rates of 260 bpm ...

In my case, the standard formulas put me around 172 maximum heart rate ... however my TRUE maximum is 206 bpm. If I were to push to 95% of my predicted/formula max during my HIIT sessions, I'd actually only push to the low 160's ... And I can run or cycle at the low 160's for 6 straight hours with no effort.

For me, it's not HIIT unless I push my intervals into the mid 190's, sometimes I hit 200+ during them. That's what makes it HIIT - the TRUE intensity. This is into the anaerobic threshold and simply can't be fueled via either lipolysis or ketolysis. You must use the glucose pathway for the true repeated anaerobic effort of HIIT. If you're not truly hitting this kind of effort, it's MODERATE-Intensity not HIGH-Intensity.

Most people that think they're doing HIIT while on 20g of carb aren't hitting anywhere near 90% of their maximum, let alone 95-100% ... I'd suggest it's closer to 80%, which is still aerobic, and why they claim to be able to do it.