I'm trying to go on a diet. I eat very little. One meal for the day? Is that good or bad?

Not good for weight. Most people who eat infrequently actually over eat. Two processes occur with prolonged daily fasting: the body enters a calorie-scavenging and storing "starvation" mode; and by the time you eat, you're hungry and tend to eat enough to store some extra. Small, frequent, healthy eating throughout the day, if feasible, is likely to be one step that will promote a healthier weight.
Bad. We are genetically designed to eat regular, small meals. Starving ourselves...Even for a few hours....Can cause our metabolism to slow and more energy to be stored as fat. Keep your metabolism going by eating frequent, smaller meals, and exercising regularly. Don't forget to build muscles....This speed up your metabolism!
Bad. One meal a day is not the best way to go on a diet.. Your metabolism is higher when you eat at least three meals a day. they should be three balanced meals with variety and moderation in portion control.