Goodness, who says to only eat once a day? Weird! If you're on a semi-fast or mono-fast maybe, but regularly? NOT good. No, for Kapha, low agni and low metabolism, best routine is a light breakfast, main meal at lunch, light dinner, no snacking after 6-8:00 pm. Skipping meals tends to slow down the metabolism further, as the body then thinks it's winter and you have to survive on fewer calories!
Meals should always include something that's heating, carminitive, bitter, or astringent. Kapha's need plenty of exercise, so the "take a short walk 15 minutes after eating" guideline is doubly important for them. Ginger tea is great for Kapha.