Yes, diets that restrict calories can be healthy, because a person that needs to lose weight and does so is healthier for it. A person losing weight is healthy, because the body still takes what it needs by feeding off its fat stores. That is the purpose of fat. The person can be healthy while they lose weight because the body knows how to compensate.
Diets that restrict calories can be healthy if done properly. Striclty cutting calories without worrying about what you eat can be disasterous but if you are smart about it, it can be healthy. One must eat healthy meals in moderation, not overeat, and plan out meals and they can cut calories while being healthy.
Diets that restrict calories can be healthy. They are healthy if they restrict calories from junk food or foods that are high in cholesterol. Reducing calories can promote health by promoting weight loss. Obesity and other excessive weight problems are a direct threat to a person's health, and the only way to reduce weight is eat less calories than you expend through exercise.
It depends on what your diet is in the first place. If you are eating 5,000 calories a day while sitting on your bum, its very healthy to cut back. You don't need that many calories, if your a couch bum. It is unhealthy if thats where you take it. If you cut neeed calories to get skinny, there are better ways to do it.
Diets that restrict calories can not be healthy. Anything that restricts the amount of calories that you need in a day can not be good for you. The amount of calories that we need is a lot in everyday and we have turned to try to count those calories in every meal.