Anyone can to explain this: many people (even health professionals) tend to think that overweight people can never be malnourished because they are healthy.

Well, I don't believe that you can be overweight and healthy unless it is muscle mass that makes you "overweight". Many overweight people actually are malnourished because they are likely eating unhealthy processed food such as fast food. When you eat this constantly, you are depriving your body of essential vitamins and nutrients. These nutrients and vitamins are essential for building muscle mass, so is exercise. If you are overweight, you are probably not exercising like you should. Unhealthy food choices, low muscle mass, and lack of exercise can dramatically lower one's metabolism. If your metabolism is slow, it takes longer for your body to take in the needed nutrients and vitamins.

a and c are the answeres