Zachary is trying to gain weight. he complains that he has a hard time eating a lot of food at one meal. you advise him to:

You should advice Zachary to: eat energy-dense snacks between meals

In order to gain weight, we need to consume more calories that we usually burn per day. Energy dense snacks tend have a high concentration of calories per serving without making us feel full due to their high concentration in fiber.  example of energy-dense snacks would be Peanut or Wheat cookies.