No carb diets, are they unhealthy if so why? And what's the lowest amount of carbohydrates a person can eat per day for optimal weight loss?

ConsistentModeration. Your metabolism is like a fire. Fuel it regularly to maximize it.Eat palm sized portion of protein and complex carb every 2-3 hr. Sprinkle 4 fruits ; 4-5 veggie portions across the day.Hydrate!water intake (10 oz x 10 times a day). Do not restrict as your body parts need all types of nutrition for optimal function.Exercise in moderation 30-50min 6days a week: fast walking, swimming, biking.
No Carb = death ! ! . Low carb diets are extremely unhealthy! you do want to avoid processed foods and simple carbs (white bread, sugar, soft drinks with sugar, bagels, etc.) but you need complex carbs and veggies have all the important micronutrients in them that do not exist in meat. You don't want no carb or low carb, you want healthy carbs. Read the book eat to live by joel fuhrman, md and get more ideas from him!