You're welcome!
Lyle McDonald, Alan Aragon, Will Brink, Brad Shoenfeld, Ian Helms, etc all have great info on this topic if nutrition.
You can eat whatever and still have good body comp but good health is also dependent upon micronutrients which is lacking in a lot of junk foods. A scientifically backed approach that I recommend is to get most of your macros from whole and minimally processed foods so as to get a diverse micronutrient profile which is essential for many physiological functions and reserve some remaining calories for the foods you enjoy that might be processed more. Usually 10-20% of your total daily cals is what I suggest for these "indulgences".
Using a friend as an example, a buddy of mine just this past May or June won his pro card at his show. He was eating brownies, ice cream, McDonald's all the way up to 4wks out from the show. He came on stage at around 4-5%.
Using myself as an example, I eat what I want, when I want and make it fit my calorie and macro needs. This includes salads, chicken breasts, eggs, meats, etc but also a ton of brownies, ice cream, cereal, fast food, greasy burgers, etc and my body composition has never been better.
Point I'm trying to make is not that you must eat all junk food or you have to eat junk food but nutrition isn't as strict as many make it out to be. In fact, a diet of all chicken and broccoli would be worse than a diverse diet that does include donuts, cookies, brownies etc bc the latter will have a more diverse micronutrient profile while also meeting caloric and macro needs. Foods can't be labeled as clean/dirty or good/bad outside the context of the entire diet so Eat what you like, make it fit your needs, and eat shit in moderation.
Yes but insulin will not overpower a calorie deficit
Fat storage and oxidation is constantly occurring. Ppl worry about the minutae, ie will this be stored as fat if I eat it, while forgetting what's really important. You're always storing and burning fat at different rates. Insulin is given far more credit than it deserves.
In your above example yes an insulin spike would send dietary fat to be stored as fat but dietary fat is stored as fat without an insulin spike too. Primary fate of the fat you eat is storage so even with low glycemic carbs your store fat. A other thing to consider is that protein spikes insulin more than carbs in certain cases but I don't see anyone scared of protein.
Think about things in the order of importance:
1) total daily calories
2) total daily macros
3) macronutrient breakdown
And way, way, way, WAYYYYYYdown the list, so low it's basically negligible until you're about to step on stage, is high GI vs low GI carbs.
50g of carbs is fine for a low carb day if carb cycling yes. I'd have ~3-4 low carb days, 1-2 medium carb days, and 1 high carb day