I did this briefly a couple years ago, following the TKD protocol over at https://reddit.com/r/ketogains (in their faq). I would add a bit of dextrose in the form of candy before my strength training. I ended up deciding that it did not help me in a noticeable way and that I was indeed getting cravings from eating the candy and wanting other things, or badly wanting to eat more than I needed for a workout. For me it was unnecessary and not a good path. I was also pushing myself far harder to try to advance in my strength training than I should have been. That's not much more than a personal anecdote I know, but, that's my experience as someone who messed around with TKD in the middle of the weight loss process while trying to push harder and harder at the gym.

I'm doing leangains (2nd time around on it) and it sounds very similar to TKD - more carbs (and for leangains more calories too) on strength training days (3x/week) and less on non-training days.

Mostly, I think everyone is a bit different and if you are interested you should just try it - if it sucks you can always stop or adapt as needed to fit your particular body.

Here is my assessment

Pros:

It works, I have been able to put on muscle and make strength gains while still losing body fat. My first round I dropped approximately 5% body fat in 12 weeks - it didn't even seem possible to me that anyone could do that, however I ran it through some of my nurse friends and they said that was totally reasonable. I have been trying to drop body fat below 25% for about 2 YEARS...and this was 12 weeks - like frackin magic.

I have really adorable back muscles now - who knew, they were there all along, hiding under the fluff.

Once you do the math and plug it into MFP, it's really easy to track (my diary is open, so you will see the "offset" values for today if you want to look)

Barring cravings, it's really easy to pass up the carby foods if you know you can have it tomorrow or the day after. So, from the standpoint of long term adherence, it was good. I stick to mostly food based carbs (beans, potato, rice, corn), not candy, but the occasional ice cream was not out of the question either.

My training days are Tu/Th/Sa - I will occasionally swap out Sat for Sun if a special event makes that a good day to be high carb, so this flexibility of being able to use the high carb days both for training and for social events made life quite a bit easier.

I can definitely bring it harder with the weights on the days I have carbs at lunch and dinner. I just have more energy to make it all happen.

My mother has also done leangains, and while she lost zero pounds, she lost over 5 inches in her waist, so clearly there is some body composition changing going on with this cyclic schedule stuff, and she's eating probably 3x the amount of food she was eating before, so definitely she's getting far better nutrition which makes me happy and is likely better for long term health.

Cons:

I had major major cravings the first couple weeks, to the point that it was definitely impacting my adherence - I altered the carb level to about half what leangains recommends and that ceased to be an issue - not sure how many carbs are recommended for TKD, but my levels are currently 35/149 but I usually actually clock in around 100 on training days, I don't force myself to hit the full amount - so technically I'm still low carb even on training days, but certainly not keto levels of low carb.

Doing the math is kind of a pain in the neck, and plugging it all into MFP and trying to figure the macro percentages to be close to the math (which is grams) is kind of a pain in the neck, probably 30 min of total annoyance, but for a 12 week program I guess I can suck up 30 min of total annoyance.

I had to redo the math after the body fat change...really, do the math again!!!

Weekends in general are so much harder than week days...during the week I can be so good and it's not even a challenge, pack lunch, come home, good snack, make dinner, food totally on point, no alcohol...then the weekend comes and I'm super busy all day so I don't eat enough, then I want to eat junk at night because I get back home and I'm famished and no food is ready, and I'm tired and I just want a glass of wine and something that doesn't take effort...and it's a fight not to just go have that glass and that junk...such a struggle...I try to do my workouts first thing in the morning on the weekends, otherwise I get too busy and they just don't happen at all...and I need to get better about weekend food planning...I'm organized 5 days a week, why is it so hard to get the last 2 days together???

planning...that's a great idea...I think I'm just kind of tired of planning everything by the weekend, but maybe if I just stuck to planning dinner...hmmmmm...might have to try that!!!