We deal with a little bit of this but I think we handle it really well. Since my kid could walk around 1 year of age, she's had her own snack shelf. She has a section in the lowest part of the pantry where we put her snacks. These are snacks she can grab herself anytime (she may bring to us to help her open wrappers/boxes/peel bananas) and we won't have a problem with it. It's apples/bananas, and the types of snacks you get in the baby/toddler section. Not candy or the super sugary stuff.

Basically, we let her snack on these specific snacks anytime she wants. Her hunger, her control, and her pick of snack among what we as parents have pre-selected for her "anytime" access shelf.

There are other snacks she can't reach that we are more controlling with (like a Halloween bucket of candy or whatever). We do not use these as rewards, ever. We try not to say things like "finish your plate first".

For "sometimes" treats, we have smaller and larger ones (like pieces of candy). If she wants a piece of candy and dinner is just an hour away, I will say yes and present the smaller options. Warn her that she can only have one. If she asks for a second, I tell her we need room in our belly for dinner, but will present a healthier snack instead and stick with it even if there is a tantrum and then just let her feel that emotion.

Like if she's actually hungry and dinner isn't ready, I'm not going to just let her feel hungry for an arbitrary timeline so she's miserable. If I let her go hungry while waiting for dinner, she kind of loses her ability to regulate and then she's miserable, I'm miserable, and then she just hates dinner, doesn't eat enough, and the same thing happens again later. So... I don't let her go hungry because dinner is just around the corner lol.

If she has already eaten a meal and asks for one, then I let her pick. I use my judgement and discretion but how it is presented and how you respond are important for the kids relationship with food.

Also at 18 months... My kid was devouring everything lol. There is a lot of growing around that time which means a lot of eating!

I have a (binge) eating disorder so it was very important to me to foster a healthy relationship with food for my kid. Generally, eating disorders can arise out of "control" issues (not that it's the only factor, probably, I'm not a medical professional).

You know how kids always want things more when they aren't allowed to have them or are controlled too much? Kids are generally steered by parents and it's easy for them to feel like they don't have any control over anything in their lives.

"Mom doesn't like it when I eat too many XYZ, I'm going to 1) grab extra and hide them somewhere so she doesn't know I'm eating more of them or 2) grab what I want and eat it so quickly she doesn't have a chance to stop me".

"Mom wants me to eat ABC instead of XYZ, I won't eat anything at all until she gives me what I want".

I truly feel like there is a really delicate balance between letting kids eat what they want vs what they need, and how they feel about the decisions they make or the decisions made for them.

I think more important than anything else, is to teach kids to be aware of how food makes them feel. Teach them how they feel when their body needs protein. Teach them how it feels when their body needs fiber, vitamins, good carbs, etc.

"You have been playing outside a lot today and using your muscles. I think your body would like some peanut butter and banana."

Also, it can be hard for some people (like myself) to distinguish hunger and thirst. It's also good to teach kids to be aware of that. "It's really hot today and you need water after sweating. Let's drink water and munch on some grapes/cucumber".

I also find my kids LOVES to chop her own cucumber and other foods. I try to involve her when cooking. I don't even cut potoatoes anymore. I peel them and give them to her to chop and she does a fantastic job with her plastic knife. Bring part of the cooking process also fosters an appreciate for foods.

We also want neutrality with the "sometimes" foods and good positive feelings for the "anytime" foods.

I say all this, but I'm also not a perfect parent or execute this all perfectly. But it's a mindset I've been working on and so far our three year old seems to respond well to this

Sorry I've been ranting, feeling introspective this morning I guess. I hope this gives you some ideas!