To suffice is to be enough, in either quality or quantity. It may not be gourmet all the time, but if your food is healthy, it will suffice.
The word suffice comes from a combination of the Latin words sub ("under") and facere ("make") that together mean "meet the need of." This need is usually the bare minimum — no leftovers, nothing fancy. The common phrase "Suffice it to say" means "I'll just say" or "All that needs to be said is...."