Lots of parents report that their children "refuse to eat." It's a completely normal stage, and by itself is usually pretty harmless (though not ideal from a nutritional point of view), and in spite of their parents' deep anxiety, their kids aren't wasting away. In fact, many of the same parents mention that their kids are in the normal weight range. They are just very, very particular about what they would choose if left to their own devices. It's so common that some development experts think it may be a way for kids not to poison themselves by sampling every plant and bug that they can get their little fingers on.
Understandably, parents get anxious about their children not eating enough, which often leads to mealtime battles, which in turn can lead to long-term food issues, up to and including serious eating disorders. The unfortunate few toddlers are blessed with eating problems that do call for medical intervention, often associated with sensory integration issues.
Kids this age can be genuinely disgusted by certain flavors and textures, and that reluctance to try various foods can last for several months to a few years. Imagine a hostess offering you grasshoppers and sheep's eyeballs at a dinner party (gasp, choke, gag…).
My 4yo grandson isn't much of a mealtime eater. He's never been much of a self-feeder, but if he's engaged in interesting conversation, he'll usually accept bites of food from his parents, which they offer because he's on the skinny side. He is usually willing to "graze" on high-quality snacks, like cut up apples and fruit, raisins, sweet peppers and cucumbers, cherry tomatoes, whole grain crackers and cheese, omelet, yogurt, olives, peanut butter on toast…. Quite a healthy diet, actually. His preferences can shift quite a bit from month to month, and are most likely signaling that his body needs more of certain nutrients. We've also noticed that if he doesn't get to eat right when he feels hungry, the feeling will often pass and he'll have absolutely no appetite when dinner is ready 25 minutes later.
Many kids are much better grazers than mealtime eaters, and that's actually a fairly healthy and natural way to eat. They can grab a few attractive/nourishing bites right when they are feeling hunger. You might consider trying that, along with having him sit with you for a little while at meals to maintain a pleasant family bond. My grandson likes to have a small, attractive plate of food which he hardly touches, say grace, make "toasts" with a little footed glass, tell stories. He's usually great company, but gets restless quickly. His parents make him stay at the table for a little while, but excuse him when he's too distracted. And his habits are getting more "civilized" by the month, so this leniency is not spoiling him.
It's completely normal for kids' appetites to disappear completely for days at a time. Making kids eat foods they dislike, aka force-feeding, makes for an unpleasant mealtime experience, which further kills appetite. It also teaches some of us to eat when we're not hungry, which can become a very unhealthy habit later on.
Have you tried baking your own "fries?" Cut fresh potatoes into strips, brush them with olive oil and salt lightly, bake in a hot oven until browned. Yummy and healthy.
I hope you'll consider offering a variety of healthy foods, and keep empty calories out of sight, or better yet, out of the house. Sugary and processed snacks are too attractive and easy, and tend to replace healthy eating even for lots of adults.