How can you get a girl fatter without her knowing?

Answer 1

While stress and genetics play a role with body weight, the biggest regulator of body fat is an energy balance of calories burned versus consumed calories. Hence you need her to stop exercising and eat more. I would suggest cascading stressful and emotionally challenging situations in her life that make her turn to food as a coping mechanism.

Also if you are in charge of the cooking you need to make sure that full fat milk, cheese etc and high sugar foods are always used. You can stir butter into just about most foods (this is done with babies and toddlers who don't like to eat much). Carbo-loading is a must - none of this Atkins rubbish. You need lots of thick white bread and pasta and potatoes. Fizzy drinks are full of calories too but they're bad calories. Alcohol is also fullof calories. Assuming she is of legal age, try giving her stout (brand name Guinness) as this given to weak patients in hospital.