Why do I fail so hard at fat/weight loss?

[BigJB12]

I try to follow the Lyle McDonald suggestion of throwing in a full diet break for 1-2 weeks to reup hormones. I've done this two times now. Both times, I dieted hard for a month and dropped 7-10 pounds accounting for water, then ate 500-1000 calories above maintance for 1-2 weeks and gained all the weight back. I can't complain too much because I gained all of my strength back as well so it wasn't like I was making reverse progress but this inability to keep weight off is rough.

[xsquid99]

Age? Height? Weight? Bodyfat estimate?

You should be limiting weight loss to about 1% of your bodyweight per week. For most people that comes out to roughly 1-2 lbs a week (so maybe 4-8) pounds a month, which is a more sustainable rate of a loss, and certainly doesn't require a "diet break" after eating in such a moderate deficit for such a short amount of time. In my mind diet breaks are more reserved for people who have been in a deficit for an extended period of time (like 6 months or more).

I've been cutting for 9 weeks now, and plan on going for another 4-5 weeks, no diet break required.

[brutalpl0x]

Why wouldn't your "break" be at maintenance?

[xsquid99]

Why wouldn't your "break" be at maintenance?

^^^^ Good question, I glossed over that... Diet breaks are typically not done in a bulking surplus.

[spradish]

You don't need a 2 week diet break after a month of dieting wherein you lost 10 lbs. If you do take one, you eat at maintenance.

[JackMan017]

Feels as if you're not 100% committed. And believe me, it's not easy, I've been there. I've done what you've done plenty of times.
If dieting was that easy, we'd all be lean with great muscle definition.
Two times now...is the 3rd time a charm?
Sounds like you're dieting too hard. A key to dieting is something that can be sustainable. Reasonable caloric deficits, sustainable deficits. Often we have to diet for longer than 1 month. For example maybe 3-4months. I'm not insinuating to go try and diet for a full year.
I'm guessing here, but the first month of your weight loss (i.e. mostly water loss) was probably 70% water 30% fat.
And sure you might feel weaker with that loss of water/glycogen. But as you know, eating a little above maintenance will regain your strength, but at the expense of your cut.
A lot of it's mental too. Accept the fact your cutting, lift as heavy and safely, with good form, as you can.
Once you get passed the first month or so of dieting, you're less likely (in my experience) to fall off the wagon. Once the results begin to kick in month 2 & 3, you start really getting excited.
You got to just commit to it. Be consistent.

[SuffolkPunch]

Have you calculated your average calorie intake including your "reefed" periods. You probably are at maintenance overall.

You almost certainly don't need refeeds, that would the preserve of people doing extreme diets - mostly women doing bodybuilding contest prep.

Just maintain a simple mild calories deficit continuously over a long period of time. Expect to feel hungry at times. Don't have "cheat meals" or "refeeds". Just stick with the plan.