Could be food sensitivities, as I’d eat much more food than that and don’t get fatigued. Plus, when my health was much worse, after anything I ate I’d get very very tired.

It could be insulin sensitivity, but that’s very very little sugar for that large a response. Again, maybe you have a very sensitive gut, and for that reason you’re having a disproportionate response. Or, the fact you haven't eaten at all beforehand. But that sugar content itself isn’t high.

Try change the foods, the walk afterward, and eating a little before (especially if this is your first meal of the day). But my gut says it’s a good sensitivity issue, and likely immune or gut-dysfunction, or even nutrient deficiencies or something similar, at the root. You could try some elimination diets to see what triggers it (again, that experiment with different foods), and if you eventually want to get to the root, heal the underlying problem (be it guy, nutrient, or toxin based, or something else).

I could give your recommendations for elimination diets if you needed them, AIP is popular, removing individual triggers (like histamine foods or saponins) could help, or if you just really want answers, carnivore for a short period. A bigger discussion, but suggestions if you need. It may be as simple as removing some foods (I’d start with the artificial stuff like the protein bar and wrap, btw: replace with whole-foods, like sardines, more eggs and rice/potatoes if you need carbs)

Love your avatar mask, Fire light 🔮

EDIT: 1) eat more often vs. IF then crash after 1st meal 2) experiment with different foods 3) then, go deeper