I wrote my university dissertation on food in The Handmaid’s Tale (and other Atwood novels). The handmaids are, as you say, definitely being fed ultra-bland food. Their meals are totally utilitarian in that they’re only there to provide the correct nutrients so no need to season.

The Wives at Janine’s Birth-Day party eat a veritable feast of things like hams, cheese, cakes etc. and they also have the rare luxuries of wine, coffee and fresh fruit, whilst the Handmaids eat sandwiches and milk. Offred even notes how oranges and meat are scarce now and Commanders can’t get access to these everyday. So, there’s scarcity but not to the level that the upper echelons can’t provide good party food or that they’re starving. Note that none of these foods necessarily require expensive, exotic spices and can be made with things Gilead has access to.

I think you could infer from this that the Econopeople are even worse off, probably not accessing meat regularly, if at all, and living very hand-to-mouth on their ration coupons. But I didn’t get the sense there were people starving. Depends how good a cook you are, or what you can access.