Eating one high calorie fatty sweet or salty item per week

Please don't take this as a personal criticism (it's 100% not) I find the question . . . kind of odd, honestly. Understandable, though. It just doesn't match my conceptual framing of weight management.

(As context, I've been calorie counting since 2015, maintaining a healthy weight since 2016, after having been overweight to😆 obese for around 30 years before that. I have a firm belief that personalization of path is the way to long-term success, which is why I don't think the above is personal criticism.)

If you stick with your (experience proven) calorie goal and activities, on average over moderate time spans (days to small number of weeks) and longer, your body fat levels will behave as expected - that's been my experience, at least, over nearly 7 year so far.

But body weight isn't just body fat, it's also water, digestive contents, lean tissue (muscle, bone, etc.), a few pounds (!) of gut microbiota that genetically isn't part of us.

In the absence of obvious calorie reasons for them: Sudden multi-pound weight changes tend to be from changes in water retention and digestive contents. Fat changes tend to be slower, more of a cumulative thing over days to a small number of weeks, depending on size of calorie deficit and amount left to lose. Muscle mass changes (absent some dire health condition - which you'd know) tend to be even slower, many weeks to months and beyond.

When you eat consistently (calories, macros, electrolytes, water) and behave consistently (exercise, daily life activity), weight will be relatively more stable, because you haven't done as much obvious stuff to affect water weight or digestive contents. (Surprising shifts in water retention can still happen, because healthy bodies do that for good reasons.)

When you start including unusual eating - the big deals are more carbs than usual or more salt than usual (even if either or both are perfectly reasonable levels, just higher than normal) - you'll tend to see bigger/wilder water and digestive contents fluctuations, so more scale-weight fluctuation as a result.

It's not fat, so it's not worth worrying about . . . but it will make the scale results more confusing, a less clear gauge of ongoing fat loss. (The fat loss plays peek-a-boo on the scale with the water/digestive-contents fluctuations.)

If you weigh daily under consistent conditions (first thing in AM, after bathroom before food/drink, same state of dress every time - tends to be good), you may be able to come to understand these fluctuations, find them less worrisome. Some people find daily weighing stressful though . . . if that's you, that might not be the best approach, I don't know.

Other than that, I don't see that there will be much effect from your weekly indulgence** on weight or nutrition, if you're within your proven calorie level averaged over (say) one week. Some individuals (but not others) might see some individual, personal effects, such as:

* A feeling of sugar rush - meaningless as long as it doesn't make you faint, unsteady, cause heart palpitations, etc.
* A later sugar crash that spikes appetite - meaningless as long as managed.
* Somewhat looser bowel movements from higher fat levels than normal (not necessarily problem-loose).
* Feeling thirstier from extra salt intake (if so, drink some).
* Urinating more as water-weight dissipates.

Those won't happen to everyone (mostly don't happen to me, generally, if indulgences are semi within reason), but IMU they're possible for some people, and could be at a problem level for a rare few. Maybe re-introduce foods gradually, see how it goes, before going all out suddenly?

** I have to say, I'm disinclined to schedule these kinds of things, like "once a week": I tend to do them when they fit in, and I feel like it. I prioritize nutrition, so it's rare for me to indulge in a calorie-dense but nutrient-sparse thing unless I'm in good shape calorie-wise and already have nutrition dialed in for the day. At my size and experience-based calorie level, I can fit in things like you describe, in reasonable portions, quite frequently.

Yesterday, for example, I had wine, cheese, a frozen Greek yogurt bar (fudge brownie flavor), a Lindt chocolate truffle, and a couple of Godiva chocolates . . . and also exceeded my protein and fiber minimums, got a good amount of MUFA/PUFA, exceeded all the MFP-tracked micro goals, got over 12 servings of veggies/fruits, within 2131 calories. That's more typical than unusual.

I do calorie bank a small amount, too, for occasional bigger indulgences (still not on a defined schedule).

It's a fun game, fitting in good nutrition from yummy food and a few treats - kind of like calorie/nutrient Tetris.

You can figure this stuff out, for yourself, if you treat it as a calm, analytical set of experiments. Even the worst that can realistically happen isn't terrible, generally. You can find a personalized routine that works for you.

Best wishes!

I eat out(fast food) once a week Friday night, and also usually have a donut on Sunday. I might skip the donut if trying to lose, but I can fit it easily into maintenance. If I stay just a little under my calories Monday-Thursday, there is enough room for fries on Friday. My long run is on sunday. My calorie burns from exercise are usually close to 1000. That leaves room for a donut and extra coffee after my run. You just have to plan ahead and budget with calories like you would money.