is dieting really that simple?

I mean if you're sticking at 1000 calories a day you're going to fail at some point, yes. Too low, not sustainable. That's a recipe for stalling, binging, and regain. Nothing you do now should be something you can't do forever and it's a very short, old, woman who doesn't move that can manage on 1000 calories a day without stressing their body out, moving less in life (Not exercise just life) and having other calorie burning things their bodies do (like temperature, hair growth, nail growth) slow or stop -- -and cortisol go up, creating other issues.

But also yes, weight loss is in fact as simple as calories in, calories out. The diet industry wants to make it complicated. You can't sell 'figure out your total daily energy expenditure and eat less than that'. They CAN sell points, exercise plans, shakes, diet plans, premade diets, and pills. They also very much get a lot of repeat business by making it complicated.

But seriously. Eat more. Use the MPF calorie guide. Stop undereating and setting yourself up to be sick and fail.

Mechanistically speaking, at the level of physics, it *is* as simple as balancing calories in and out (with in < out for weight loss).

As a practical matter, all of the calories in and out (and the goals) are *estimates*, so there are some skills to be learned to estimate. Fortunately, close is good enough, so it's possibly to lose weight by attentive calorie counting.

In actual human bodies, calorie balance isn't static, it's dynamic.

It's *not* true that you can eat so few calories that your metabolism "breaks" and you can't lose fat any more. (If that could happen, no one would ever starve to death, or they'd be fat when they died of starvation. Sadly, many people die worldwide daily from starvation, and they're emaciated (maybe bloated belly, but skeletal otherwise) when they do so.

What is true is that if we cut calories severely, we can become fatigued (so move less, in possibly subconscious ways); and convince our body there's a famine going on, so it turns down body temperature a tiny bit, slows hair growth, and compromises health in other less-important-to-survival ways (so conserves calories by using them only for the very highest priority bodily functions). In that scenario, weight loss can be slower than expected. On top of that, the stress of undereating can cause stress-related water retention that slowly creeps up, and hides fat loss on the scale, making you think you're not losing fat when you still are. Those things are danger signs: Feeling cold, feeling weak, feeling fatigued, brittle nails, hair breaking/thinning (though those last two are usually weeks late to be a helpful warning).

On top of all of that, there can be psychological aspects that make the easy physics be hard in practice: Some of us have learned to use food as a reward, to self-sooth, to counter stress or boredom, and more. We can even subconsciously experience fatness as protective, in some cases (a way to hide, kind of). And there's more, by far, on the psychological side. That part is very very individual, and can be difficult even beyond the counting.

Even beyond that, we have comfortable habits (what we're used to eating, and activities we like to do), others things are uncomfortable/unfamiliar (new foods or exercise); and perceptions of what's "normal" for eating and exercise (what our families and friends generally do, commonly). Those affect our thinking.

Some of us say weight loss is simple (because it's just calorie balance) but not easy (because of the dynamic, psychological, habitual, and normative influences).

It's not so much the 3 bears, as finding the new habits, looking at it as a problem of averages over time, and adjusting based on results.

Just my opinions.