Hard boiled eggs are a great snack. and bacon...and meat in general. Munching on a wedge of homemade (not my home) salami as I type this... Like avocados as well.
Salads are great (takes a lot of veggies to get 40 grams) with oil and a tad of vinegar.
Nuts and fruit can sneak up on ya a bit.
Why under 40?